JPH0448970A - How to form a coating film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a new silver oxide film that has excellent cosmetic properties, coating film performance, and weather resistance, such as those used in automobiles, and is curable at room temperature or by heating.

[Conventional techniques and their problems] As a method for forming coating films on automobile exterior panels, cosmetic appearance,
In order to improve weather resistance, a two-coat one-bake method is becoming mainstream, in which a base paint containing colored pigments and/or metallic pigments is applied, followed by a clear paint, and both layers are cured simultaneously. This method is useful in that it is easy to develop excellent coating film performance, but because it uses an amino resin or polyisocyanate as a crosslinking agent, it does not have sufficient cosmetic properties. There was a problem in that deterioration of crosslinking progressed due to heat and cooling during dew, acid rain, etc., resulting in coating film defects.

An object of the present invention is to provide a novel method for forming a coating film for use in automobiles, which has higher cosmetic properties, weather resistance, etc., and can be cured at room temperature or by heating.

[Means for Solving the Problems] The gist of the present invention is to apply a base coat paint containing a colored pigment and/or a metallic pigment, and then apply (a) polymerization in one molecule to this coated surface. Reactive oligomer and/or radically polymerizable vinyl monomer containing one or more sexually unsaturated groups
7 to 75% by weight, (1)) 3 to 15% by weight of a compound represented by the following structural formula [I], A: Active hydrogen-containing selected from carboxylic acid, alcoholic hydroxyl, thiol, amide, and secondary amine Residue portion B excluding active hydrogen atoms of the compound: Residue portions excluding active hydrogen atoms of an active hydrogen-containing group selected from carboxyl group, hydroxyl group, mercapto group, and amide R1, R2, R3, R4: Hydrogen atom or alkyl group having 1 to 3 carbon atoms R,: hydrogen atom or alkyl having 1 to 1 o carbon atoms 1: number of active hydrogen groups when A contains active hydrogen mho or 1 n: integer of 1 or more (c) An acrylic copolymer having a small number of polymerizable unsaturated groups in the molecule (1% to 90N1), (cl) a metal dryer to 100 parts by weight of the total amount of components (a) to (C) above. 0 to 1 part of Oil, and (e) the polymerization initiator to the total of 11 parts of the above Ca) to (c) components.
0.00 parts by weight. 1-3. A method for forming a coating film, characterized in that a clear coating composition containing 0 parts by weight is coated and two layers are cross-linked and cured at the same time.

Hereinafter, the coating film forming method of the present invention will be specifically explained.

The base foot 2 material is not particularly limited and may be adjusted by a known method. That is, it is common to use acrylic resin, polyester resin, thermoplastic resin, etc. as the base resin, and use amine resin, polyisocyanate, etc. as the crosslinking agent.

Specific examples of amino resins include aminotriazine, urea, dicyandiamide, N,N-ethylene urea methylolated products, which are alkyl etherified with cyclohexanol or alkanols having 1 to 6 carbon atoms. For example, methyl etherified melamine resin, butyl etherified melamine resin, etc. are suitable.

Next, the polyisocyanate compound is a compound having two or more incyanate groups in one molecule, and specifically, a di(or tri)incyanate compound, for example,
Aliphatic incyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, ethylene diisocyanate, inphorone diisocyanate, lysine diisocyanate, xylylene diisocyanate, methylxylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, 4.4 -methylenebis(phenylisocyanate), 3.3-diisocyanate, 1. 4
- Aromatic incyanates such as dimethylbenzene, triphenylmethane diisocyanate, and 1-methyl-2
, 4-diisocyanate cyclohexanone, 4,4-methylene bis(cyclohexyl isocyanate), alicyclic incyanate such as cyclohexane diisocyanate, hexamethyl diisocyanate isocyanurate, and the like.

The reactive oligomer of composition (a) used in the clear coat paint is used in an amount of 7 to 75% by weight; if it is less than 7% by weight, the water resistance will decrease, and if it exceeds 75% by weight, the cured coating will deteriorate. The appearance of the membrane deteriorates. Specifically, the reactive oligomers include trimethylolpropane-trimethacrylate, tetraethylene glycol dimethacrylate, and l.

3-butylene glyfur diacrylate, 1. Examples include 6-hexanediol diacrylate, pentaerythritol-tetramethacrylate, dipentaerythritol pentaacrylate, hydrogenated bisphenol A epoxy dimethacrylate, bisphenol A-diglycidyl ether diacrylate, tripropylene glycol diacrylate, etc. It is not limited to.

Further, the radically polymerizable vinyl monomers include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, 2-ethylhexyl acrylate, styrene, allyl acetate,
Examples include vinyl acetate and the like, but are not particularly limited. Actually, the radically polymerizable vinyl monomer is oligomer 060
Up to % by weight can be substituted. If it exceeds 60% by weight, coating film performance such as water resistance and solvent resistance will deteriorate.

Next, the compound (b) represented by the structural formula (I) is a carboxylic acid, an alcoholic hydrocysyl, a hydroxyl group, a thiol,
It is synthesized by reacting a compound having a plurality of active hydrogen-containing groups selected from amides and secondary amines with a compound having an activated double bond and an epoxy group. The compound has a usage range of 3 to 15% by weight;
If it is less than 3% by weight, the crosslinking density of the cured coating film will be low and sufficient water resistance will not be obtained, and if it exceeds 15% by weight, hardness and acid resistance will decrease. Specific examples of the compound having a plurality of active hydrogen-containing groups include low molecular weight polyols such as ethylene glycol, sorbitol, or mannitol; examples of the polyol include polyethylene glycol, polyglycerol, polyglycitol, Examples of the alcohol include allyl alcohol and allylthiol, and examples of the dicarboxylic acid include maleic acid, fumaric acid, malonic acid, and phthalic acid. Among these, polyhydric alcohols having 2 to 6 carbon atoms are preferred.

A compound having a double bond and an epoxy group has the following general formula / \ R1~CH-CH-CH2-B-(CH,)II-C=
C-R4 R,R.

B: Residue moiety excluding active hydrogen atoms of an active hydrogen-containing group selected from carboxyl group, hydroxyl group, mercapto group, and amide R1, R, R, R: hydrogen atom or alkyl group having 1 to 3 carbon atoms m It is represented by 20 or 1, and preferred examples include butadiene monooxide, sorbitol glycidyl ether, allyl glycidyl ether, and vinylcyclohexene monooxide.

In coating film formation, the above composition alone is insufficient in terms of sag control, arrangement of colored pigments and/or metallic pigments in the base layer, adhesion between the base and clear layers, etc.1, but the following compositions By using (C), this problem can be effectively improved. Also, without using amino resin or polyisocyanate as a crosslinking agent,
Since there are no by-products, a more beautiful appearance and smoothness can be achieved.

The acrylic copolymer of composition (C) can be synthesized by subjecting an epoxy group-containing acrylic copolymer to an addition reaction with an unsaturated basic acid or a polybasic acid using an amine compound as a catalyst.

The monomers constituting the acrylic copolymer having an epoxy group include glycidyl (meth)acrylate, (meth)allyl glycidyl ether, metaglycidyl (meth)acrylic acid ester, etc. As a polymerizable navinyl monomer,
Hydroxyl (meth)acrylate such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc.
Acrylates, adducts of 2-hydroxyethyl (meth)acrylate and ethylene oxide, adducts of 2-hydroxyethyl (meth)acrylate and propylene oxide, 2-hydroxyethyl (meth)acrylate and ε-
Vinyl monomers containing hydroxyl groups, such as adducts of 2-hydroxyethyl (meth)acrylate and organic lactones, such as adducts of caprolactone, styrene, α-methylstyrene,
Styrene derivatives such as vinyltoluene, polymerizable unsaturated nitriles such as (meth)acroyl nitrile, vinyl acetate,
Vinyl esters such as vinyl propionate, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-butoxymethyl (meth)
N-alkoxy substituted amides such as acrylamide, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate,
2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, (
Examples include (meth)acrylic acid esters such as stearyl meth)acrylate.

As unsaturated basic acids or unsaturated polybasic acids, (
Meth)acrylic acid, itaconic acid, fumaric acid, crotonic acid, maleic acid, monomethyl itaconate, monobutyl itaconate, monomethyl maleate, monobutyl maleate, etc. can be selected.

Amine compounds as reaction catalysts include triethylamine,
Common organic bases such as diethylethanolamine and triethanolamine are used, and the amount used is suitably no more than that necessary to neutralize the acid value of the acrylic copolymer.

Composition (c) can be used in a range of 10 to 90%. If the content is less than 10%, the appearance deteriorates, and
If it exceeds 90% by weight, acid resistance decreases.

Metal dryer (l significantly accelerates copolymerization, and its usage range is 0 to 1.0 parts by weight based on the total weight of components (a) to (C). 1.0 parts by weight) Exceeding this is not preferable because the cosmetic properties deteriorate.Specifically, cobalt and manganese salts and soluble complexes.For example, cobaltous acetate, citrate,
Acetyl acetate 2-ethylhexanoate and the corresponding manganous salts and complexes. The metal dryer is usually added in solution in a suitable solvent in order to disperse it throughout the reaction mixture.

The range of use of the polymerization initiator (e) is 0.1 to 3.0 parts by weight based on 100 parts by weight of the total amount of components (8) to (c). 0. If it is less than 1 part by weight, sufficient coating film hardness cannot be obtained, and if it exceeds 3.0 parts by weight, the stability of the violet will decrease, which is not preferable. A polymerization initiator is essential because a metal dryer alone will result in a coated surface with poor smoothness. Examples of the polymerization initiator used here include benzoyl peroxide, cumene hydroperoxide, di-t-butyl hydroperoxide, dicumyl peroxide,
Examples include t-butyl peracetate, t-butyl perbenzoate, t-butyl hydropero beef side, etc.
In addition, as azo compounds, azobisisobutyronitrile, 2,2-azobis(2-methylbutyronitrile), 1
, 1-azobis(cyclohexane-1-carbonitrile), 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(2-methylpropane), etc., and those that are particularly limited isn't it.

Furthermore, surface conditioners, anti-cissing agents, ultraviolet absorbers, antioxidants, organic solvents, and other additives may be added to the clear coating composition as required.

In the present invention, both the base foot and the violet film formed by overcoating the clear coat can be cured at room temperature or by heating, so it can be applied to plastic products that would deform and deteriorate when heated to about 120°C or higher. In addition, applying both of the above coats to metal objects eliminates the need for high-temperature heating, making it possible to save energy.Furthermore, it can be applied to wood, glass, inorganic materials, etc., and is visually appealing. It is also possible to achieve integral painting of metal and plastic on vehicle exterior panels.

The coating film forming method of the present invention can be applied directly to an object to be coated, or to an object coated with an undercoat or an intermediate coat. For the undercoat and intermediate coating, known ones can be used. For example, as the undercoat, cationic or anionic electrodeposition paint, room temperature drying or heat curing water-based or organic solvent-based undercoating, etc. can be,
Examples of the intermediate coating include polyester resin-based or fatty acid-modified alkyd resin-based paints.

The method of applying the base coat to these surfaces is not particularly limited, and examples thereof include brush painting, spray painting, roll painting, and the like. Among these, in the case of spray coating, it is preferable to adjust the viscosity of the base coat to 10 to 20 seconds (Ford Cup 4/20°C). The thickness of the coating film is suitably 10 to 20 microns, particularly 15 to 20 microns, based on the dry coating film. The method of applying the clear coat is not limited either, and the above-mentioned methods can be used. Among these, when spray painting, the viscosity of the top foot should be adjusted for 10 to 30 seconds (Ford Cup 4/
It is desirable to adjust the temperature to 20°C.

The coating film thickness is 10 to looμ based on the dry coating, especially,
30-60μ is suitable. The top coat can be applied to the base coated surface at any time, and in particular the base coat film can be applied for at least 1 minute at room temperature, especially for 3 to 3 minutes.
It is preferable to paint the top foot after allowing it to stand for 10 minutes. to.

If the coating is left at room temperature to 140° C. or lower after coating, the crosslinking reaction will proceed, forming a crosslinked coating film with significantly improved appearance, weather resistance, etc.

The present invention will be explained below using examples.

Example of manufacturing base coat paint: In a container equipped with a stirrer, temperature controller, and condenser
40 parts by weight of toluene, 1O1 n-butyl acetate! ! 1 part was added and heated with stirring to raise the temperature to 100°C. Next, 101.5 parts by weight of a solution having the following composition was added dropwise over 4 hours, followed by 0.5 parts by weight of benzoyl peroxide. A solution consisting of 6 parts by weight and 20 parts by weight of toluene was added dropwise over 30 minutes.

Styrene 5 parts by weight 2 parts by weight 45 parts by weight 36 parts by weight Methacrylic acid Methyl methacrylate ethyl acrylate 12 parts by weight Benzoyl peroxide 1.5 parts by weight The reaction solution was further heated and stirred at 100°C for 2 hours. After increasing the reaction rate, 30 parts by weight of toluene was added to terminate the reaction, resulting in a solid content of 50 parts by weight and a weight average molecular weight of 60,000.
An acrylic resin face (1) was obtained.

Next, the compounds listed in Table 1 were thoroughly mixed and stirred to obtain base paints (1) to (3), and then diluted with the mixed solvent listed in Table 1 for 13 seconds (Ford Cup #4/20'C). did.

Example of Preparation of Compound (b) Ethylene glycol was added to a reactor and then reacted with allyl glycidyl ether in a molar ratio of 1:12 at about 70° C. in the presence of a boron trifluoride catalyst. Allyl glycidyl ether was added dropwise over 5 hours, neutralized with an aqueous sodium hydroxide solution, and the aqueous layer was removed to obtain a composition (b) after dehydration.

<Production Example of Acrylic Polymer (C)> 1 part of 53.3fi of xylene was added to a container equipped with a stirrer, a temperature control device, and a condenser. The temperature was raised to 130°C with stirring, and then 2 parts of azobisin butyronitrile was added to 100 parts by weight of the monomer mixture listed in Table 2.
Weight parts and t-butylberoxyinpropyl carbonate
1 part of 1-2jij was added dropwise over 4 hours.

Next, 1 part by weight of azobisisobutyronitrile O was added to 3 parts by weight.
Added 4 times at 0 minute intervals. Furthermore, after heating and stirring at 120"C for 1 hour to increase the reaction rate, 13.3 parts xylene 1
part was added. After that, the temperature was lowered to 70℃ over 1 hour, and 0.2 parts by weight of Hydrogynone and triethylamine were added.
After adding 1 part by weight, 20.5 parts by weight of acrylic acid was added to 1 part by weight.
It dripped over time. After completion of the dropwise addition, compositions (c)-1 and (c)-2 were obtained by continuing to heat and stir for 6 hours.

Production example of acrylic resin face (2)> Solbefuso #10 in a container equipped with a stirrer, temperature control device, and condenser
0 was added in an amount of 53.3 parts by weight. While stirring, increase the temperature to 12
The temperature was raised to 0°C, and then 2 parts by weight of azobisisobutyronitrile and 2 parts by weight of t-butylperoxyisopropyl carbonate were added to 100 parts by weight of the following monomer mixture, and the mixture was added dropwise over 3 hours. Then, azobisisobutyronitrile 0. 1 part by weight was added four times at 30 minute intervals. Furthermore, after heating and stirring at 120° C. for 2 hours to increase the reaction rate, 13.3 parts by weight of n-butyl acetate was added to terminate the reaction, and an acrylic resin face (2) was obtained.

Styrene methacrylate n-butyl methacrylate t-butyl methacrylate 2-ethylhexyl methacrylate 25 parts by weight of 2-hydrobovine diethyl 3 parts by weight 201 parts 5 parts by weight 29 parts by weight methacrylate 18 parts by weight <Examples 1 to 6, Comparative Example 1 〜7〉 After degreasing the base coat, intermediate coat, sanding, and water layer in advance, apply the base coat paint (1) to
(3) was applied to a dry film thickness of 15μ, left for 3 minutes, then a clear foot paint was applied to a film thickness of 35μ, and 10μ was applied at room temperature.
After standing for a minute, it was baked under the curing conditions shown in Table 3. Table 4 shows the finished appearance and coating performance evaluation results of the two-piece, one-bake laminated film thus obtained. The Examples were superior to the Comparative Examples in hardness, appearance, weather resistance, and water resistance.

[Effects of the Invention] As detailed above, the method of the present invention enables curing even at room temperature, and the formed coating film exhibits excellent appearance, smoothness, acid resistance, weather resistance, and water resistance. Therefore, its industrial significance is extremely high.

Claims (1)

[Scope of Claims] A base coat paint containing a colored pigment and/or a metallic pigment is applied, and then (a) a reactive oligomer containing one or more polymerizable unsaturated groups per molecule is applied to the painted surface. and/or 7 to 75% by weight of a radically polymerizable vinyl monomer, (b) 3 to 15% by weight of a compound represented by the following structural formula [I], ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ A: Carboxylic acid , alcoholic hydroxyl, thiol, amide, and a secondary amine, excluding the active hydrogen atom of the active hydrogen-containing compound B: activity of the active hydrogen-containing group selected from the carboxyl group, hydroxyl group, mercapto group, and amide Residue moieties excluding hydrogen atoms R_1, R_2, R_3, R_4: Hydrogen atom or alkyl group having 1 to 3 carbon atoms R_6: Hydrogen atom or alkyl group having 1 to 10 carbon atoms 1: When containing active hydrogen in A Number of active hydrogen groups m: 0 or 1 n: an integer of 1 or more (c) an acrylic copolymer having at least one polymerizable unsaturated group in the molecule, 10 to 90% by weight, (d) a metal dryer 0 to 1.0 parts by weight per 100 parts by weight of the total amount of components (a) to (c) above, and (e) a polymerization initiator to 1 part of the total amount of components (a) to (c) above.
1. A method for forming a coating film, which comprises applying a clear coating composition of 0.1 to 3.0 parts by weight to 0.00 parts by weight, and crosslinking and curing two layers at the same time.