JP4859087B2 - Water-based paint and painting method - Google Patents

Description

  The present invention relates to a novel water-based metallic paint and a coating method using the water-based metallic paint.

In general, a metallic paint contains a metal powder pigment such as aluminum powder as a pigment, and can exhibit a unique aesthetic appearance by the action of the metal powder pigment, and can also exhibit performance such as heat ray reflection. .
Such characteristics in metallic paints are largely due to the leafing phenomenon of metal powder pigments. The leafing phenomenon is a phenomenon in which the metal powder pigment floats on the upper layer of the coating film and is oriented parallel to the surface to be coated due to surface tension generated during the coating film formation.
However, when the clear paint is applied repeatedly after applying the metallic paint, the interlaminar adhesion between the metallic paint and the clear paint is reduced due to the leafing phenomenon of the metal powder pigment as described above, which causes problems such as interfacial peeling. May be caused.

  As a technique for improving such a problem, a formulation in which a silane coupling agent is blended with a metallic paint has been proposed. For example, in Japanese Patent Publication No. 6-19080 (Patent Document 1), in a metallic coating composition comprising a metal powder, a resin, a solvent and a coating additive, a silane coupling agent is added in an amount of 0.1 to the total solid content. It is described that 5% by weight is incorporated. In Japanese Patent Laid-Open No. 2000-178478 (Patent Document 2), a silane coupling agent is further mixed into a metallic paint containing a bright pigment and a phosphoric acid group-containing compound obtained by pulverizing a deposited metal film into a metal piece. It is described. Japanese Patent Application Laid-Open No. 2000-186234 (Patent Document 3) describes a metallic coating composition containing a fluorine-containing copolymer, a silane coupling agent, and a metallic pigment.

However, all of the metallic paints described in the above patent documents are solvent-based paints using a strong solvent such as toluene, xylene, butyl acetate or the like as a medium. From the viewpoint of environmental problems, resource saving, occupational safety and health, etc., it is better to refrain from using such strong solvents, and it is desirable to switch to water-based paints using water as a medium.
However, it is difficult to control the reactivity between water and the silane coupling agent by simply adding a silane coupling agent to the metallic paint using water as a medium. I can't get enough. That is, all of the techniques of the above-mentioned patent documents are directed only to solvent-based paints and cannot be applied to water-based paints as they are.

Japanese Patent Publication No. 6-19080 JP 2000-178478 A JP 2000-186234 A

  The present invention has been made in view of the above problems, and an object thereof is to sufficiently improve the problem of poor adhesion and interfacial peeling in a water-based metallic paint.

  As a result of intensive studies to achieve the above object, the present inventor has conceived an aqueous metallic paint obtained by mixing a silane coupling agent with a specific formulation, and has completed the present invention.

That is, the present invention has the following characteristics.
1. The synthetic resin emulsion (I), the metal powder pigment (II), and the modifier (III) are essential components, and the metal powder pigment (II) is 1 per 100 parts by weight of the solid content of the synthetic resin emulsion (I). A method for producing a water-based paint, wherein 100 parts by weight is mixed and the modifier (III) is mixed while satisfying the following conditions (a) to (c).
(A) The modifier (III) is obtained by mixing the silane coupling agent (p) and the solvent (q) having a solubility in water of 10 g / 100 g or less with only two components.
(A) The weight ratio of the silane coupling agent (p) and the solvent (q) in the modifier (III) is 1:99 to 95: 5.
(C) The modifier (III) is mixed in an amount of 0.1 to 30 parts by weight with respect to 100 parts by weight of the solid content of the synthetic resin emulsion (I).
2. Further, the coloring pigment (IV) is an essential component, and the coloring pigment (IV) is mixed in an amount of 0.1 to 200 parts by weight with respect to 100 parts by weight of the solid content of the synthetic resin emulsion (I). . A method for producing the water-based paint as described.
3.1. Or 2. A coating method comprising: coating a water-based paint obtained by the production method described above, and then coating a water-based clear paint.

The paint of the present invention is a water-based paint using water as a medium, which is preferable in terms of environmental problems, resource saving, occupational safety and health, and the like.
If the coating material of this invention is used, the interlayer adhesiveness of a metallic coating film and the clear coating film on it will be improved, and generation | occurrence | production of coating film abnormalities, such as interface peeling, can be suppressed.

  Hereinafter, the best mode for carrying out the present invention will be described.

In the aqueous metallic paint of the present invention, the synthetic resin emulsion (I) is used as a binder.
Specifically, as the synthetic resin emulsion (I), for example, a vinyl acetate resin emulsion, a vinyl chloride resin emulsion, an epoxy resin emulsion, an acrylic resin emulsion, a urethane resin emulsion, an acrylic silicon resin emulsion, a fluororesin emulsion, or a composite thereof And the like. These can be used alone or in combination of two or more.

  Further, the synthetic resin emulsion (I) may have crosslinking reactivity. When the synthetic resin emulsion (I) is a crosslinking reaction type synthetic resin emulsion, the water resistance, weather resistance, adhesion and the like of the coating film can be improved. The crosslinking reaction type synthetic resin emulsion may be either one that causes a crosslinking reaction by itself or one that causes a crosslinking reaction by a separately mixed crosslinking agent. Such crosslinking reactivity includes, for example, carboxyl group and metal ion, carboxyl group and carbodiimide group, carboxyl group and epoxy group, carboxyl group and aziridine group, carboxyl group and oxazoline group, hydroxyl group and isocyanate group, carbonyl group and hydrazide group. It can be imparted by combining reactive functional groups such as epoxy groups and amino groups, aldo groups and semicarbazide groups, keto groups and semicarbazide groups, and alkoxyl groups.

The production method of the synthetic resin emulsion (I) is not particularly limited, and for example, emulsion polymerization, soap-free emulsion polymerization, dispersion polymerization, feed emulsion polymerization, feed dispersion polymerization, seed emulsion polymerization, seed dispersion polymerization and the like can be employed. .
The glass transition temperature of the synthetic resin emulsion (I) is usually about −60 to 80 ° C. (preferably −40 to 60 ° C.). Moreover, the average particle diameter of synthetic resin emulsion (I) is about 0.05-0.4 micrometer normally.

  The metal powder pigment (II) in the present invention is a component that imparts a metallic feeling to the formed coating film of the present paint. Examples of the metal powder pigment (II) that can be used include aluminum, copper, nickel, magnesium, zinc, brass, and alloys thereof. Among these, an aluminum pigment is suitable in the present invention. As the aluminum pigment, those subjected to various surface treatments can also be used. For example, after atomized aluminum powder and / or aluminum foil is pulverized using a grinding aid such as fatty acid, aliphatic amine, aliphatic amide, aliphatic alcohol, etc., chromic acid, phosphoric acid, phosphate, phosphorus Those treated with acid ester, vanadate, vanadium oxide, molybdate, silica or the like can be used. If the aluminum pigment which gave such a process is used, generation | occurrence | production of hydrogen gas by contact with water can be suppressed.

  The shape of the metal powder pigment (II) is usually scaly, and the average particle size is usually about 1 to 50 μm (preferably 5 to 30 μm).

  The mixing ratio of the metal powder pigment (II) is usually 1 to 100 parts by weight, preferably 2 to 80 parts by weight with respect to 100 parts by weight of the solid content of the synthetic resin emulsion (I). When the amount of the metal powder pigment (II) is less than 1 part by weight, a sufficient metallic feeling cannot be obtained in the formed coating film. When the amount of the metal powder pigment (II) is more than 100 parts by weight, the fluidity of the paint is lowered, which hinders the painting operation. There is a risk of causing.

The water-based metallic paint of the present invention contains the modifier (III) as an essential component in addition to the above-described components. In the present invention, the modifier (III) is mixed while satisfying the following conditions (a) to (c).
(A) The modifier (III) is a mixture of a silane coupling agent (p) and a solvent (q) having a solubility in water of 10 g / 100 g or less.
(A) The weight ratio of the silane coupling agent (p) to the solvent (q) in the modifier (III) is 1:99 to 95: 5.
(C) The modifier (III) is mixed in an amount of 0.1 to 30 parts by weight with respect to 100 parts by weight of the solid content of the synthetic resin emulsion (I).

In the present invention, by mixing the modifier (III) under the above conditions, the problem of poor adhesion and interfacial peeling in the aqueous metallic paint can be sufficiently improved. Specifically, it is possible to prevent adhesion and interfacial peeling between the metallic coating film formed by the aqueous metallic paint of the present invention and the clear coating film formed thereon. The mechanism of action is not clear, but is presumably due to the following points.
First, the silane coupling agent (p) is distributed in the particles of the synthetic resin emulsion (I) in a state dissolved in the solvent (q). That is, in this invention, it can suppress that a silane coupling agent (p) deactivates by contact with water.
Secondly, the silane coupling agent (p) reacts with a functional group (such as a hydroxyl group) on the surface of the metal powder pigment (II) at the time of coating film formation. At this time, the solvent (q) elutes the grinding aid (such as fatty acid) remaining on the surface of the metal powder pigment (II) and assists the reaction of the silane coupling agent (p).
Due to the above action, it is considered that the adhesion improving effect by the silane coupling agent (p) is maximized in the aqueous metallic paint of the present invention.

  Examples of the silane coupling agent (q) include β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylethoxysilane, γ -Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylsilane, N -Β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyltrimethoxysilane, isocyanate functional silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxyproo Pyrmethyl Diet Examples include silane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, N- [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane, and one or two of these. More than seeds can be used.

Examples of the solvent (q) having a solubility in water of 10 g / 100 g or less include ethylene glycol monohexyl ether, ethylene glycol-2-ethylhexyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol dibutyl ether, diethylene glycol monohexyl ether, diethylene glycol mono Butyl ether acetate, diethylene glycol dibutyl ether, propylene glycol monobutyl ether, propylene glycol phenyl ether, propylene glycol diacetate, dipropylene glycol monobutyl ether, dipropylene glycol tertiary butyl ether, tripropylene glycol monobutyl ether, octylene glycol, 2-ethylhexylene Glycol, , 2,4-trimethyl-1,3-pentanediol mono-isobutyrate, benzyl alcohol and the like, may be used alone or two or more thereof.
The solubility of the solvent (q) in water is less than 10 g / 100 g, but preferably less than 5 g / 100 g.

  The weight ratio of the silane coupling agent (p) and the solvent (q) is usually 1:99 to 95: 5, preferably 5:95 to 80:20. In this invention, the adhesiveness of a formed coating film can fully be improved by using both components together in this ratio.

  The mixing ratio of the modifier (III) in the aqueous metallic paint is usually 0.1 to 30 parts by weight, preferably 0.2 to 20 parts by weight, based on 100 parts by weight of the solid content of the synthetic resin emulsion (I). is there. If the mixing ratio of the modifier (III) is within such a range, the adhesion of the formed coating film can be sufficiently improved. When the mixing ratio of the modifier (III) is too small, it becomes difficult to obtain an adhesion improving effect. When the mixing ratio is too large, there is a possibility that problems such as taking more time than necessary for drying the coating film and causing stickiness on the surface of the coating film may occur.

In the present invention, a color pigment (IV) other than the metal powder pigment can also be used. By mixing the colored pigment (IV) with the aqueous metallic paint, the hue of the paint can be adjusted, and metallic coatings having various colors can be obtained.
The coloring pigment (IV) is not particularly limited as long as it can be used in a normal paint, and examples thereof include titanium oxide, carbon black, ferric oxide (bengala), yellow iron oxide, ocher, ultramarine, and cobalt green. Inorganic pigments, organic pigments such as azo, naphthol, pyrazolone, anthraquinone, perylene, quinacridone, disazo, isoindolinone, benzimidazole, phthalocyanine, and quinophthalone can be used. These color pigments (IV) can be appropriately used alone or in combination of two or more depending on the desired color.

  In addition to the above-mentioned components, the water-based metallic paint of the present invention can be mixed with components that can be used in ordinary paints. Examples of such components include thickeners, film-forming aids, extender pigments, leveling agents, wetting agents, plasticizers, antifreezing agents, antiseptics, antifungal agents, anti-algae agents, antibacterial agents, dispersants, and adsorption agents. Agents, ultraviolet absorbers, antioxidants, light stabilizers, catalysts, crosslinking agents and the like.

  The water-based metallic paint of the present invention can be produced by mixing and stirring the above-mentioned components by a conventional method. At this time, the modifier (III) is desirably mixed in the presence of at least the synthetic resin emulsion (I). According to this method, the effects of the present invention are sufficiently exhibited. The mixing order of the metal powder pigment (II), the color pigment (IV), etc. is not particularly limited.

The water-based metallic paint of the present invention can be applied directly to various materials such as metal, concrete, plastic, etc., or after applying some surface treatment (such as a surface treatment with a sealer, filler, surfacer, putty, etc.). It is also possible. As a coating method, various methods such as brush coating, spray coating, and roller coating can be employed. The coating amount at the time of coating is usually about 0.1 to 0.5 kg / m ² . At the time of application, the viscosity of the paint can be appropriately adjusted by diluting with water or the like. The dilution ratio is usually about 0 to 20% by weight. Drying after coating is usually performed at room temperature, but can be heated as necessary.

  After applying the water-based metallic paint, the water-based clear paint is usually applied. By applying such a water-based clear paint, durability, stain resistance, aesthetics (glossiness), and the like can be enhanced. Furthermore, in the present invention, since the interlayer adhesion between the metallic coating and the clear coating is sufficiently ensured, the occurrence of coating film abnormalities such as interfacial peeling can be suppressed.

The composition of the water-based clear coating is not particularly limited, and for example, acrylic resin-based, urethane resin-based, epoxy resin-based, acrylic silicon resin-based, fluorine resin-based coatings, and the like can be used. Moreover, a colored type can be used as long as the aesthetics of the lower metallic coating are not significantly impaired.
The method for applying the water-based clear coating may be a known method, and various methods such as brush coating, spray coating, and roller coating can be employed. The coating amount at the time of coating is usually about 0.1 to 0.5 kg / m ² . At the time of application, the viscosity of the paint can be appropriately adjusted by diluting with water or the like. The dilution ratio is usually about 0 to 20% by weight. Drying after applying the water-based clear coating is usually performed at room temperature, but may be heated as necessary.

  Examples are given below to clarify the features of the present invention.

(Modifier A)
γ-aminopropyltriethoxysilane and diethylene glycol dibutyl ether (water solubility 0.3 g / 100 g) were mixed at a weight ratio of 20:80 to obtain modifier A.

(Modifier B)
γ-aminopropyltriethoxysilane and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (solubility in water 0.9 g / 100 g) were mixed at a weight ratio of 20:80 for modification. Agent B was obtained.

(Modifier C)
γ-aminopropyltriethoxysilane and propylene glycol monopropyl ether (water solubility ∞) were mixed at a weight ratio of 20:80 to obtain modifier C.

Example 1
Water-based paint by mixing and stirring 18 parts by weight of metal powder pigment, 20 parts by weight of modifier A, 2 parts by weight of thickener, and 1 part by weight of antifoaming agent in order in a usual manner with respect to 200 parts by weight of synthetic resin emulsion. A was produced. In addition, the following were used as raw materials other than the modifier.
Synthetic resin emulsion: acrylic resin emulsion (methyl methacrylate-styrene-2-ethylhexyl acrylate-acrylic acid copolymer, solid content 50% by weight, glass transition temperature 20 ° C.)
・ Metal powder pigment: Aluminum pigment (average particle size 15μm)
・ Thickener: Urethane-based associative thickener ・ Defoamer: Mineral oil-based defoamer

Spray coating the aqueous paint A obtained by the above method to a slate plate that has been pre-sealed with a coating amount of 300 g / m2, and drying for 24 hours in standard conditions (temperature 23 ° C, relative humidity 50%) Thereafter, an acrylic silicone resin water-based clear paint was spray-coated at a coating amount of 150 g / m 2 and cured in a standard state for 14 days. By the above method, a test plate having a metallic silver appearance was obtained.
The test plate was subjected to a total of 10 cycles of water-cooling (23 ° C.) 18 hours → −20 ° C. 3 hours → 50 ° C. 3 hours, followed by a total of 10 cycles. The adhesion was evaluated by a cross-cut tape method according to JIS K 5600-5-6. As a result, the adhesion became “◯”. The evaluation criteria for adhesion are “◯” when the peeled area is less than 5%, “△” when the peeled area is 5% or more and less than 15%, and the area of the peeled defect is Those with 15% or more were evaluated as “x”.

(Example 2)
For 200 parts by weight of synthetic resin emulsion, 18 parts by weight of metal powder pigment, 20 parts by weight of modifier A, 1 part by weight of coloring pigment (phthalocyanine blue pigment), 2 parts by weight of thickener, and 1 part by weight of antifoaming agent A water-based paint B was produced by mixing and stirring in order.
When a test plate was produced in the same manner as in Example 1 except that the water-based paint B was used in place of the water-based paint A, a test plate having a light blue metallic appearance was obtained. The adhesion test result of this test plate was “◯”.

(Example 3)
For 200 parts by weight of the synthetic resin emulsion, 18 parts by weight of metal powder pigment, 20 parts by weight of modifier B, 1 part by weight of coloring pigment (phthalocyanine blue pigment), 2 parts by weight of thickener, and 1 part by weight of antifoaming agent are conventional methods. A water-based paint C was produced by mixing and stirring in order.
When a test plate was produced in the same manner as in Example 1 except that the water-based paint C was used in place of the water-based paint A, a test plate having a light blue metallic appearance was obtained. The adhesion test result of this test plate was “◯”.

(Comparative Example 1)
To 200 parts by weight of the synthetic resin emulsion, 18 parts by weight of a metal powder pigment, 4 parts by weight of γ-aminopropyltriethoxysilane, 2 parts by weight of a thickener, and 1 part by weight of an antifoaming agent are sequentially mixed and stirred in a conventional manner. Thus, water-based paint D was produced.
An adhesion test was conducted in the same manner as in Example 1 except that the water-based paint D was used in place of the water-based paint A, and the result was “x”.

(Comparative Example 2)
For 200 parts by weight of synthetic resin emulsion, 18 parts by weight of metal powder pigment, 4 parts by weight of γ-aminopropyltriethoxysilane, 16 parts by weight of diethylene glycol dibutyl ether, 2 parts by weight of thickener and 1 part by weight of antifoaming agent are used in a conventional manner. A water-based paint E was produced by sequentially mixing and stirring at.
An adhesion test was performed in the same manner as in Example 1 except that the water-based paint E was used in place of the water-based paint A. The result was “x”.

(Comparative Example 3)
Aqueous paint by mixing and stirring 18 parts by weight of metal powder pigment, 20 parts by weight of modifier C, 2 parts by weight of thickener, and 1 part by weight of defoaming agent in order in a conventional manner with respect to 200 parts by weight of synthetic resin emulsion. F was produced.
An adhesion test was performed in the same manner as in Example 1 except that the water-based paint F was used in place of the water-based paint A, and the result was “x”.

Claims (3)

The synthetic resin emulsion (I), the metal powder pigment (II), and the modifier (III) are essential components, and the metal powder pigment (II) is 1 per 100 parts by weight of the solid content of the synthetic resin emulsion (I). A method for producing a water-based paint, wherein 100 parts by weight is mixed and the modifier (III) is mixed while satisfying the following conditions (a) to (c).
(A) The modifier (III) is obtained by mixing the silane coupling agent (p) and the solvent (q) having a solubility in water of 10 g / 100 g or less with only two components.
(A) The weight ratio of the silane coupling agent (p) and the solvent (q) in the modifier (III) is 1:99 to 95: 5.
(C) The modifier (III) is mixed in an amount of 0.1 to 30 parts by weight with respect to 100 parts by weight of the solid content of the synthetic resin emulsion (I).   Furthermore, the coloring pigment (IV) is an essential component, and the coloring pigment (IV) is mixed in an amount of 0.1 to 200 parts by weight with respect to 100 parts by weight of the solid content of the synthetic resin emulsion (I). Item 2. A method for producing a water-based paint according to Item 1. 3. A coating method comprising applying a water-based clear paint after applying the water-based paint obtained by the production method according to claim 1 or 2.