JPH07331118A - Composition for coating and method of formation of coating film using the same - Google Patents

Abstract

PURPOSE:To obtain an aqueous coating composition for a metallic base that is improved in drying properties with the coating film performance retained without causing sprayed or overlapped unevenness by incorporating an aqueous resin, an aqueous cellulose derivative, and a rheology control agent in specified amounts. CONSTITUTION:(A) An aqueous resin, (B) an aqueous cellulose derivative, (C) a rhelology control agent, and (D) a metallic pigment and/or a coloring pigment are used as essential components, as the aqueous resin (A), an acrylic resin emulsion or a mixture of a urethane resin emulsion and an aqueous acrylic resin solution in a weight ratio of 100:0 to 50:50 in terms of solids is used, and 1 to 30wt.% component B and 0.1 to 20wt.% component C are contained based on the solids of the resin A. A usual primer coating is applied on a metal or plastic base, then the present composition is applied thereon as a base coating, and after drying, a clear coating is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition and a method for forming a coating film using the same, and more particularly, to a coating containing an aqueous resin, an aqueous cellulose derivative and a rheology control agent, which is effective as an aqueous metallic base paint for automobile repair. The present invention relates to a composition for use and a film forming method using the same.

[0002]

2. Description of the Related Art Conventionally, acrylic lacquers and acrylic urethane paints have been used in the field of automobile repair paints. However, acrylic urethanes are used in organic solvent systems from the viewpoints of quick-drying, coating skin, weather resistance and the like. Paint is the mainstream. In addition, in this field, a metallic finish color in which a clear paint is applied on top of a paint containing an aluminum paste (hereinafter referred to as a metallic base) has become mainstream in this field.

A problem with the metallic finish color is that the distribution and orientation of aluminum becomes uneven during coating of the metallic base, resulting in unevenness (flicker unevenness and the following description), and after leaving the metallic base at room temperature until it is dry to the touch. The clear coating is applied on top of that, but the clear coating causes uneven distribution and orientation of aluminum in the metallic base layer thereunder, which causes unevenness (modorimura and the following description).

In recent years, it has been desired to use an aqueous base paint as a base paint from the viewpoint of improving the working environment and environmental protection, and even if such an aqueous base paint is used, it is strongly desired to solve the above problems. It is rare. In the organic solvent system, it is said that the resin composition of the base coating contains a fibrin derivative such as nitrocellulose or cellulose acetate butyrate to accelerate the drying property and control the orientation of aluminum. It is insoluble and its effect cannot be retained in water. Carboxymethyl cellulose as a cellulose derivative for water-based paints,
Although there are hydroxyethyl cellulose and the like, even if they are used as an aqueous base, they only have the effect of increasing the viscosity of the paint, and at present, they have not yet solved the above-mentioned flicker unevenness and moduli unevenness.

As an aqueous cellulose derivative
Although a cellulose derivative which improves the drying property has been proposed in Japanese Patent No. 39301, Japanese Patent Application Laid-Open No. 5-194912, etc., the cellulose derivative has not yet been applied to an aqueous metallic base for automobile repair.

[0006]

SUMMARY OF THE INVENTION Therefore, the present inventors have developed an aqueous coating composition for a metallic base which has improved coating properties such as durability and improved drying property, and which is free from fluffy unevenness and moduli unevenness. As a result of intensive studies to obtain the above, the inventors have found that the above problems can be solved by containing a specific amount of an aqueous resin, an aqueous cellulose derivative and a rheology control agent, and have reached the present invention.

That is, the present invention provides (A) an aqueous resin,
(B) aqueous cellulose derivative, (C) rheology control agent, and (D) metallic pigment and / or coloring pigment as essential components, and (B) relative to (A) resin solid content
1 to 30 wt% of component and 0.1 to 20 wt% of component (C)
A multilayer coating formed by coating a coating composition characterized by containing a base coating composition containing a metallic pigment and / or a coloring pigment, and applying a clear coating composition to form a transparent coating film on the coating surface. The present invention provides a method for forming a coating film, characterized in that the coating composition described above is used as the base paint in the formation of the coating composition.

First, the coating composition of the present invention will be described.

(A) Aqueous Resin The aqueous resin contains water as a main solvent or dispersion medium, and may be an acrylic resin aqueous solution, an acrylic resin emulsion, a urethane resin emulsion, or the like, and at least one or more selected from them. .

The above acrylic resin aqueous solution is a water-soluble acrylic resin dissolved in water. Specifically, it is made water-soluble by introducing an acid group such as a carboxyl group and neutralizing it with an amine or the like. is there. Such a carboxyl group-containing acrylic resin can be obtained by copolymerizing a carboxyl group-containing monomer with another acrylic monomer.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and the like, and other acrylic monomers include, for example, methyl acrylate, ethyl acrylate, propyl acrylate. , Isopropyl acrylate,
Butyl acrylate, hexyl acrylate, acrylic acid 2
-Ethylhexyl, octyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, lauryl methacrylate, etc. (Meth) acrylic acid C1 to C20
Alkyl ester; C2-C8 hydroxyalkyl ester of (meth) acrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate; dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, N-butoxymethyl acrylamide, N , N-dimethyl acrylamide and other nitrogen-containing monomers; glycidyl acrylate, glycidyl methacrylate, etc.
More than one species can be used. Further, vinyl monomers other than acrylic monomers such as vinyl acetate, vinyl propionate, styrene, α-methylstyrene, vinyltoluene, acrylonitrile, methacrylonitrile, butadiene and isoprene can be used.

The copolymerization reaction of the above monomers can be carried out by a known method, for example, azobisisobutyronitrile,
It is carried out in an organic solvent compatible with water such as butyl cellosolve using a radical polymerization catalyst such as benzoyl peroxide or ammonium persulfate. The water-soluble acrylic resin obtained has an acid value of about 20 to about 150 and a number average molecular weight of about 3,000 to about 100,000.

Neutralization of the acrylic resin is carried out with an amine, and examples of such amine include ammonia and
Ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, isopropylamine, diisopropylamine, monoethanolamine, butylamine, dibutylamine, ethylenediamine, methylethanolamine and the like, particularly ammonia,
It is preferable to use triethylamine or the like from the viewpoint of drying property. The neutralization amount is 0.3 to 1.
A range of 5 is common.

The acrylic resin emulsion comprises acrylic resin particles uniformly dispersed in an aqueous medium,
For example, the following emulsions are included.

A water-dispersible acrylic resin in the form of fine particles having an average particle diameter of 0.05 to 1.0 μ obtained by emulsion polymerization of a vinyl monomer in the presence of a dispersion stabilizer such as a surfactant. It will be done. The vinyl monomer to be emulsion-polymerized is preferably one selected from the carboxyl group-containing monomers exemplified for the above water-soluble acrylic resin and other monomers, and, if necessary, a polyunsaturated polymer having two or more polymerizable unsaturated bonds in one molecule. It is preferable to use a small amount of a vinyl compound in combination since an intraparticle crosslinked water-dispersible acrylic resin is obtained and the coating film performance is improved.

Examples of the dispersion stabilizer include nonionic surfactants such as polyoxyethylene nonylphenyl ether, anionic surfactants such as polyoxyethylene alkyl allyl ether sulfate ester salt, and acid value of 20 to 1
50, a water-soluble resin such as an acrylic resin having a number average molecular weight of about 5,000 to 30,000 is used.

Examples of the polyvinyl compound include ethylene glycol acrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate,
Tetraethylene glycol dimethacrylate, 1,6-
Hexanediol diacrylate, divinylbenzene,
Examples thereof include trimethylolpropane triacrylate and the like. In each compound, it is preferable that the reactivity of two or more unsaturated bonds contained in each compound is not significantly different, and the diene compound is not included here.

The water-dispersible acrylic resin produced here is also preferably neutralized with the amine.

As the urethane resin emulsion, an emulsion obtained by reacting an isocyanate group-containing prepolymer with a polyisocyanate, a polyol and a dihydroxy acid in the presence of water is used.

Examples of such an emulsion include (I) aliphatic and / or alicyclic polyisocyanate (a), polymer polyol (b), dimethylolalkanoic acid (c), and optionally a chain extender ( A carboxyl group-containing polyurethane resin emulsion in which a prepolymer (e) containing an excess isocyanate group obtained by polymerizing d) by a one-shot method or a multistage method, a monoamine (f) and water are added in an arbitrary order, and emulsified and dispersed in water, and (II ) A carboxyl group-containing polyurethane resin emulsion in which a chain extender (g), an emulsifier and water are optionally added to the prepolymer (e) in an arbitrary order to emulsify and disperse in water is included.

(A) constituting the above prepolymer (e)
As the aliphatic and / or alicyclic polyisocyanate,
For example, hexamethylene diisocyanate, 2,2,4-
Aliphatic diisocyanates having 2 to 12 carbon atoms such as trimethylhexane diisocyanate and lysine diisocyanate; 1,4-cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexylene diisocyanate, isopropylidene cyclohexyl-4,4
Alicyclic diisocyanates having 4 to 18 carbon atoms such as ′ -diisocyanate; modified products of these diisocyanates (carbodiimide, uretdione, modified products containing uretoimine, etc.); and mixtures of two or more thereof. Of these, alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, isophorone diisocyanate, and 4,4′-dicyclohexylmethane diisocyanate are preferable.

(B) constituting the above prepolymer (e)
The high molecular weight polyol preferably has a number average molecular weight of 500 to
5,000, preferably 1,000 to 3,000 polyether diols and polyester diols. For example, those obtained by polymerizing or copolymerizing (block or random) alkylene oxides (ethylene oxide, propylene oxide, butylene oxide, etc.) and / or heterocyclic ethers (tetrahydrofuran, etc.), such as polyethylene glycol, polypropylene glycol,
Polyethylene-propylene (block or random) glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctamethylene ether glycol; dicarboxylic acid (adipic acid,
Succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid, etc.) and glycols (ethylene glycol, propylene glycol, 1,4-butanediol,
1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, bishydroxymethylcyclohexane, etc.), such as polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, poly Neopentyl adipate, poly-3-methylpentyl adipate, polyethylene / butylene adipate, poly neopentyl /
Hexyl adipate; polylactone diols such as polycaprolactone diol, poly-3-methylvalerolactone diol; polycarbonate diol; and mixtures of two or more thereof.

(C) constituting the prepolymer (e)
Examples of dimethylolalkanoic acid include dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutyric acid, and the like, and preferred one is dimethylolpropionic acid. The amount of dimethylolalkanoic acid is 0.5 to 0.5 in the prepolymer (e) as a carboxyl group (—COOH).
The amount is 20% by weight, preferably 1 to 10% by weight.

As the chain extender (d) which can be used if necessary, low molecular weight (number average molecular weight less than 500) polyol, polyamine and the like are preferable. Examples of the low-molecular weight polyols include glycols and their alkylene oxide low-molar adducts (molecular weights less than 500) listed as the raw materials for the polyester diols; trihydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and their alkylene oxides low. Molar adducts (molecular weight less than 500); and mixtures of two or more thereof.

As the polyamine, primary and / or
Or containing two or more secondary amino groups, specifically ethylenediamine, tetramethylenediamine,
Examples include monohydroxyethyldiethylenediamine and isophoronediamine.

The chain extender (d) is 0 to 20% by weight, preferably 0.5 to 1 based on the high molecular weight polyol (b).
It is 0% by weight.

The prepolymer (e) is the above-mentioned (a) to (a).
(C) and optionally the chain extender (d) can be synthesized by a one-shot or multi-step method. The (a)-
The mixing ratio of the component (d) may be such that the prepolymer (e) has an isocyanate group, but normally, the isocyanate group / hydroxyl group equivalent ratio is preferably in the range of 1.1 to 1.9. The prepolymer (e) can be synthesized by reacting a hydroxyl group with an isocyanate group according to a conventionally known method.

In order to produce the emulsion (I) using the prepolymer (e), the prepolymer (e), the monoamine (f) and water may be added in any order and self-emulsifying and dispersing in water.

As the monoamine (f), any of primary to tertiary amines can be used, and specifically, ammonia, lower alkylamines (methylamine, ethylamine, butylamine, dimethylamine, diethylamine, Trimethylamine, triethylamine, tributylamine, etc.), alicyclic amine (cyclohexylamine, etc.), heterocyclic amine (morpholine, pyridine, N
-Methylmorpholine, N-ethylmorpholine and the like) and alkanolamines (monoethanolamine, monoisopropanolamine, diethanolamine, diisopropanolamine, N-dimethylethanolamine, N-diethylethanolamine and the like).

The compounding ratio of the monoamine (f) is usually 0. 1 with respect to 1 equivalent of the carboxyl group in the prepolymer (e).
It is in the range of 5 to 1 equivalent.

In order to produce the emulsion (II) using the prepolymer (e), a chain extender (g), if necessary, an emulsifier and water are added to the prepolymer (e) in any order.
It can be produced by emulsifying and dispersing in water. As the chain extender (g), it is preferable to use the polyamine described in the component of the chain extender (d). As the emulsifier, for example, nonionic surfactants such as higher alcohols and alkylene oxide adducts and anionic surfactants such as alkylbenzene sulfonates are preferable.

The polyamine compounded in the polyurethane emulsion has two or more primary amino groups in one molecule.

The polyamine may have a functional group such as a secondary amino group, a tertiary amino group and a hydroxyl group in addition to the primary amino group. The skeleton constituting the polyamine may contain a hydrocarbon bond and an ether bond, an ester bond, or an amide bond in the hydrocarbon bond.

Specific examples of polyamines include ethylenediamine, 1,3-diaminopropane, hexamethylenediamine, 2,5-dimethylhexamethylenediamine, diethylenetriamine, triethylenetetramine, dimethylaminopropylamine, tetraethylenepentamine,
Aliphatic polyamines such as diethylaminopropylamine and pentaethylenehexamine, alicyclic polyamines such as diaminodicyclohexylmethane and isophoronediamine, aromatic aliphatic polyamines such as xylylenediamine, metaphenylene diamine, aromatic polyamines such as diaminodiphenylmethane, etc. Can be mentioned. Further, when a hydrophilic polyamine which is soluble in water is used as the polyamine, it is particularly preferable to use this because it has excellent storage stability.

It is desirable that the above polyamine is added in an amount of about 1 to 30 parts by weight, preferably about 3 to 15 parts by weight, based on 100 parts by weight of the resin solid content of the carboxyl group-containing polyurethane emulsion.

In the present invention, the above-mentioned acrylic resin aqueous solution, acrylic resin emulsion, and urethane resin emulsion are used as the aqueous resin (A), for example, acrylic resin emulsion or urethane resin emulsion and acrylic resin aqueous solution in a solid content weight ratio of 100 /. 0-50 / 50
It is particularly preferable to use in the range from the viewpoint of coating film performance such as water resistance and adhesion.

Further, in the present invention, the water-based resins listed above may be added with known water-soluble or water-dispersible resins other than these, such as alkyd resin type, polyester resin type, isocyanate group-containing resin and silyl group-containing resin. You may add according to.

(B) Aqueous Cellulose Derivative As the aqueous cellulose derivative used in the present invention, an aqueous dispersion of an aqueous resin and nitrocellulose can be used, but an aqueous cellulose derivative represented by the following general formula is preferable. Can be used. [PYR. (X) _x (ONO ₂ ) _y (OH) _z ] _n (I) (In the formula, PYR. Represents a pyranose ring to be C ₆ H ₇ O _2, and X represents COOH, O (CH ₂ ) _p. COOH, O (C
at least one hydrophilic group selected from _q H _2q O) _r H and O (C _q H _2q O) _r NO ₂ , where p is an integer of 1-3, q is an integer of 2-3, and r is 1 Indicates an integer of -10. In addition, 0 <
x <3, 0 <y <3, 0 ≦ z <3, and x + y + z
= 3, and n represents an integer of 20 to 500. As specific examples of the above, for example, when the hydrophilic group X is COOH, a nitric acid ester such as alginic acid or pectic acid,
Examples of those in which X is O (CH ₂ ) _p COOH include nitrates of carboxyalkyl cellulose such as carboxymethyl cellulose and carboxyethyl cellulose, and nitrates of carboxyalkyl starch such as carboxymethyl starch and carboxyethyl starch. Furthermore, X is O
(C _q H _2q O) _r hydroxyethyl cellulose as the H, nitrate esters of hydroxyalkyl cellulose such as hydroxypropyl cellulose, nitrate esters of alkyl starches such as hydroxyethyl starch and the like. X
Said X is O as but those _{O (C q H 2q O)} r NO 2
In (C _q H _2q O) _r H, a partial O (C _q H _2q
O) _r H groups are nitrated. These cellulosic derivatives may contain small amounts of other ether and ester groups. Of these, nitric acid esters of carboxyalkyl cellulose such as carboxymethyl cellulose are particularly preferable in the present invention.

In the cellulose derivative, the substitution degree x of the hydrophilic group X is preferably 0.2 to 1.5, and the substitution degree y of the nitrate ester group is preferably 0.4 to 2.2. In particular, those having a degree of substitution y of the nitrate ester group of 1.5 to 2.2 are particularly suitable for an aqueous metallic base from the viewpoint of preventing flicker and moduli.

It is preferable that the ionic groups contained in the cellulose derivative are at least partially neutralized with a neutralizing agent.

(C) Rheology Control Agent The rheology control agent used in the present invention may be a conventionally known inorganic or organic rheology control agent, for example, aluminum-magnesium silicate, sodium-magnesium silicate or montmorillonite type. Layered silicates such as sodium-magnesium-fluorine-lithium silicate; water-soluble cellulose ethers such as hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose; polyvinyl alcohol, poly (meth) acrylamide, poly (meth) acrylic acid, polyvinylpyrrolidone; Examples include urethane-based or polyacrylate-based thickeners such as hydrophobic group-containing ethoxylated urethane,
Of these, the alkali swelling type polyacrylic acid type is particularly preferably used from the viewpoints of controlling the viscosity of the coating material, preventing flicker, and the like.

The composition of the present invention comprises 1 to 30 parts by weight of the aqueous cellulose derivative (B) with respect to the resin solid content of the aqueous resin (A).
wt%, preferably 5-15 wt%, and the rheology control agent (C) 0.1-20 wt%, preferably 1-2
Contains 0 wt%. When the content of the component (B) is less than 1 wt%, the drying property is insufficient and modo-uniformity is likely to occur, while when it exceeds 30 wt%, the adhesion and water resistance of the coating film deteriorate, which is not preferable. Further, if the content of the component (C) is less than 0.1 wt%, it is difficult to prevent uneven fluff.
When it exceeds wt%, the prevention of flicker unevenness is not recognized and the appearance of the coating film is apt to be deteriorated, which is not preferable.

(D) Metallic Pigment and / or Coloring Pigment The metallic pigment and / or coloring pigment used in the present invention is
Metallic pigments and / or coloring pigments usually used in the field of paints can be used, and examples thereof include aluminum paste, pearl powder, graphite, MIO, titanium white, carbon black, and fullerocyanine blue.

Further, the composition of the present invention may contain an extender pigment, an organic solvent, and an additive for an aqueous coating, if necessary.
As the organic solvent, hydrophilic solvents such as alcohol type and cellosolve type can be used.

Next, a method for forming a coating film using the composition of the present invention will be described.

In the method of the present invention, a base coating material containing a metallic pigment and / or a coloring pigment is applied, and a clear coating material for forming a transparent coating film is applied to the surface of the base material. The above composition of the present invention is used as a base paint.

Specific examples of the coated surface to which the composition of the present invention is applied include those obtained by subjecting a metal or plastic substrate to ordinary primer coating, and are particularly suitable for the repair coated surface of automobile bodies. In that case, first, after the damaged portion is polished and putty-filled, the composition of the present invention can be applied after the usual primer coating is applied. The resulting base coating film has a dry film thickness of 10 to 30 μm. A base coating film using the composition of the present invention is applied at room temperature to about 80 ° C.
After drying at a temperature of 5 to 60 minutes, a clear paint is applied.

The clear coating used in the method of the present invention is mainly an organic solvent type coating (including non-aqueous dispersion type). Specifically, a resin having an active hydrogen-containing functional group such as a hydroxyl group, for example, a hydroxyl group-containing coating is used. Urethane-curing paint containing at least one selected from acrylic resin, fluororesin, fluorinated acrylic resin, etc. and a polyisocyanate compound as the main component, or lacquer paint containing cellulose acetate butyrate-modified acrylic resin as the main component. Is preferred.

The clear paint is blended with an organic solvent such as toluene, xylene, butyl acetate, methyl ethyl ketone, and butyl alcohol; paint additives such as a surface conditioner, an ultraviolet absorber, a curing catalyst, and a pigment, if necessary. it can.

The clear coating film has a dry film thickness of 30 to 100.
μm is suitable.

As the coating method, for both base coating and clear coating, ordinary spray coating, electrostatic coating, etc. are adopted, but other coating methods are not particularly limited.

[0052]

EFFECTS OF THE INVENTION The composition of the present invention contains a specific amount of an aqueous resin, an aqueous cellulose derivative and a rheology control agent, so that it is quick-drying and does not cause flicker or moduli unevenness, and has improved coating performance such as durability. An excellent coating film can be provided, and it is very useful as a composition for an aqueous metallic base, especially in the field of automobile repair paints. Further, according to the method of the present invention, it is possible to form a multi-layer coating having excellent finish appearance and coating performance as a finish coating for automobile repair coating.

[0053]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition, part and% show a weight part and weight%, respectively.

Production of Aqueous Resin Production Example 1 75 parts of butyl cellosolve was added to a reaction vessel and heated to 115 ° C. in a nitrogen stream. Acrylic acid n
-A mixture of 32 parts of butyl, 49 parts of methyl methacrylate, 15 parts of 2-hydroxyethyl methacrylate, 4 parts of acrylic acid and 1 part of azoisobutyronitrile was added over 3 hours. After the addition was completed, the mixture was aged at 115 ° C. for 30 minutes, a mixture of 1 part of azoisobutyronitrile and 115 parts of butyl cellosolve was added over 1 hour, and after aged for 30 minutes, 2 minutes at 50 ° C.
It was filtered through 00 mesh nylon cloth. The acid value of the obtained reaction product was 31, the viscosity was Z4 (Gardner foam viscometer), and the solid content was 55%. A 50% acrylic resin aqueous solution (A-1) was obtained by neutralizing this with an equivalent amount of triethylamine and further adding deionized water.

Production Example 2 Polybutylene adipate 11 having a number average molecular weight of 2,000
5.5 parts, polycaprolactone diol having a number average molecular weight of 2,000 115.5 parts, dimethylolpropionic acid 2
3.2 parts, 6.5 parts of 1,4-butanediol and 120.1 parts of 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (IPDI) were charged into a polymerization vessel and stirred. The reaction was carried out at 85 ° C. for 7 hours in a nitrogen stream to obtain a terminal NCO prepolymer having an NCO content of 4.0%. Then cool the prepolymer to 50 ° C.,
After 165 parts of acetone was added and uniformly dissolved, 15.7 parts of triethylamine were added with stirring, 600 parts of ion-exchanged water was added while maintaining the temperature at 50 ° C or lower, and the obtained aqueous dispersion was kept at 50 ° C for 2 hours. After completing the water elongation reaction, acetone was distilled off under reduced pressure at 70 ° C. or lower to obtain a urethane resin emulsion (A-2) having a solid content of 39%.

Production Example 3 140 parts of deionized water and 30% "Newcol 707" were placed in a reaction vessel.
SF "(surfactant, manufactured by Nippon Emulsifier) 2.5 parts and monomer mixture (methyl methacrylate 55 parts, styrene 8)
Parts, 9 parts of n-butyl acrylate, 5 parts of 2-hydroxyethyl acrylate, 2 parts of 1,6-hexanediol diacrylate and 1 part of methacrylic acid), and mixed with stirring in a nitrogen stream. At 60 ° C., 3 parts of 3% ammonium persulfate was added. The temperature is then raised to 80 ° C. to balance the remaining 79 parts of the monomer mixture, 30% “Newcol 707S.
F ”2.5 parts, a monomer emulsion consisting of 4 parts of 3% ammonium persulfate and 42 parts of deionized water was added to the reaction vessel using a metering pump over 4 hours, and aged for 1 hour after the addition was completed. .

Further, at 80 ° C., a monomer mixture (5 parts of methyl methacrylate, 7 parts of n-butyl acrylate, 5 parts of 2-ethylhexyl acrylate, 3 parts of methacrylic acid and 30%) is added.
20.5 parts of "Newcol 707SF" and 4 parts of 3% ammonium persulfate are simultaneously dropped in parallel into the reaction vessel over 1.5 hours. After the addition was completed, the mixture was aged for 1 hour, diluted with 30 parts of deionized water, and filtered at 200C with 200 mesh nylon cloth. Deionized water was further added to this filtrate to adjust the pH to 7.5 with triethylamine, and the average particle size was 0.1 μm.
m, solid content 20% acrylic resin emulsion (A-
3) was obtained.

Aqueous cellulose derivative "WHH" (nitric acid ester of carboxymethylcellulose, solid content 50%) manufactured by Asahi Kasei Kogyo Co., Ltd. was added to a mixed solution of 57 parts of adjusted water of an aqueous cellulose derivative and 21 parts of butyl cellosolve.
Parts were added with stirring with a disper, and 2 parts of triethylamine were gradually added to obtain a 10% aqueous cellulose solution (B).

Preparation of Aluminum Paste Aluminum paste (metal content 65
%) 23 parts and butyl cellosolve 25 parts, and the mixture was stirred for 1 hour to obtain a concentrated aluminum pigment liquid (D).

Examples 1 to 4 and Comparative Examples 1 to 4 The aluminum pastes, aqueous resin solutions obtained in the above production examples,
The aqueous cellulose solution and deionized water were sequentially added with stirring in the formulations shown in Table 1 below, and the mixture was further stirred for 1 hour. "Primal ASE-60" (made by Rohm and Haas, alkali-swelling polyacrylic acid thickener) was added to this mixture in the composition shown in the same table, and the mixture was added with 5% ammonia water.
A metallic base paint having a solid content of 15% was obtained at pH = 8. Table 1 shows the solid content.

[0061]

[Table 1]

Examples 5-8 and Comparative Examples 5-8 Commercially available lacquer primer surfacer was coated on a mild steel plate of 300 × 100 × 0.8 mm with a dry film thickness of 40 μ, and dried at room temperature for 30 minutes and then # 400 water resistant polishing. Polish with paper,
It was a coated plate. Each of the base paints obtained above was applied to this with a spray gun so as to have a dry film thickness of 15 μm, allowed to stand for 15 minutes, and then forcedly dried at 60 ° C. for 15 minutes, followed by “Retan PG2KM clear” (Kansai Paint Co., Ltd.). (Urethane resin-based clear) was applied by a spray gun to a dry film thickness of 40 to 50 μm and forcedly dried at 60 ° C. for 20 minutes to obtain each coated plate.

Table 2 shows the metallic finish and performance test results of the coating films of the obtained coated plates. The test method is as follows.

(* 1) Metallic Finishing Property At the time of preparing the coated plate, flicker unevenness was evaluated after the base paint was applied, and moduli unevenness was visually evaluated after the clear paint was applied. (○: No unevenness, Δ: Occurrence of unevenness, ×: Significant unevenness)

(* 2) Adhesive property A coating film (20 μm) of “TC-71 clear” (manufactured by Kansai Paint Co., Ltd., amino acrylic resin type) was formed on the substrate to be coated as an old coating film for outer panels of automobiles. The above base paint and clear paint are applied according to the above method to make test coated plates, which are immersed in tap water (20 ° C) for 7 days and taken out, and then cross-cut into a coating film, and adhesive cellophane tape is peeled off. The coating surface after the test was evaluated. (○: No peeling, △:
(Slight peeling, ×: Marked peeling)

(* 3) Water resistance Each coated plate obtained in the same manner as in (* 2) above was treated with tap water (20
The film was immersed for 72 hours in (° C.) and taken out, and the state of the coating film after standing for 2 hours was visually evaluated. Those with no abnormalities such as glossiness and blisters were rated as ◯, and those with abnormalities were rated as x.

[0067]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B05D 7/24 302 P 0823-4F T 0823-4F C09D 5/38 PRF 101/08 PCT (72) Inventor Hajime Yushima 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Kansai Paint Co., Ltd.

Claims (8)

[Claims] 1. An (A) aqueous resin, (B) an aqueous cellulose-based derivative, (C) a rheology control agent, and (D) a metallic pigment and / or a coloring pigment as essential components, and (A) a resin solid content. A coating composition comprising 1 to 30 wt% of the component (B) and 0.1 to 20 wt% of the component (C). 2. The composition according to claim 1, wherein the aqueous resin (A) is at least one selected from an acrylic resin aqueous solution, an acrylic resin emulsion and a urethane resin emulsion. 3. An acrylic resin emulsion or urethane resin emulsion as an aqueous resin (A) and an acrylic resin aqueous solution in a solid content weight ratio of 100/0 to 50/50.
The composition according to claim 1, which is used in the range of. 4. The composition according to claim 1, wherein the aqueous cellulose derivative (B) is represented by the following general formula. [PYR. (X) _x (ONO ₂ ) _y (OH) _z ] _n (I) (In the formula, PYR. Represents a pyranose ring of C ₆ H ₇ O ₂ , and X represents COOH, O (CH ₂ ) _p COOH. , O (C _q
H _2q O) _r H, O (C _q H _2q O) _r NO _2, at least one hydrophilic group, provided that p is an integer of 1-3 and q is 2
-3 is an integer, and r is an integer of 1-10. In addition, 0 <x
<3, 0 <y <3, 0 ≦ z <3, and x + y + z = 3
And n represents an integer of 20 to 500. ) 5. The composition according to claim 4, wherein the aqueous cellulose derivative (B) is a nitrate ester of carboxyalkyl cellulose. 6. The composition according to claim 1, wherein the rheology control agent (C) is a polyacrylic acid type. 7. A base coating composition comprising a metallic pigment and / or a coloring pigment blended thereon, and a clear coating composition for forming a transparent coating film on the coated surface, to form a multi-layer coating, the base coating composition comprising: A method for forming a film, which comprises using the composition according to claim 1. 8. The method according to claim 7, wherein the clear coating is an organic solvent type coating containing, as a main component, at least one selected from a hydroxyl group-containing acrylic resin, a fluororesin, a fluorinated acrylic resin and the like and a polyisocyanate compound. .