JPH07258585A - Water-based coating composition and variable-color coating film - Google Patents

Abstract

PURPOSE:To obtain a water-based coating composition improved in dispersion and storage stabilities by dispersing water-dispersible microcapsules containing a photochromic substance and a brilliant pigment in a water-based coating material. CONSTITUTION:1-95wt.% water-dispersible microcapsules having a mean particle diameter of 1-50mum and containing a photochromic substance and 0.1-40wt.% brilliant pigment are dispersed in a water-based coating material containing a binder resin to obtain a water-based coating composition. A color-base coating film 12 containing a coloring pigment, a variable-color coating film 13 made of the above water-based coating composition and a clear coating film 14 are formed on a substrate 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous coating composition containing a photochromic substance with good dispersion stability and capable of imparting a novel design property, and a color-variable coating film using the same.

[0002]

2. Description of the Related Art A water-based paint is a paint using water as a diluent, and the use of water-based paint has been increasing in various fields as the emission regulations of organic solvents have become stricter in recent years. In addition, various new coating materials and coating systems have been developed and studied with the recent diversification of coating appearance designs and advancement of appearance quality. The use of photochromic substances is being studied as one of the materials that can impart such a new coating appearance. The photochromic substance is a substance exhibiting a photochromic phenomenon in which the color thereof is changed by receiving light (ultraviolet rays or visible light having a short wavelength), and the original color is restored in a dark place.

Japanese Unexamined Patent Publication (Kokai) No. 63-296871 discloses a technique in which a photochromic compound is mixed with an organic solvent-based acrylic resin and used as a paint. Japanese Patent Laid-Open No. 3-250064 also discloses a coating film formed by mixing a photochromic compound with an organic solvent-based paint. Since photochromic compounds are added to organic solvent-based paints, these photochromic compounds are blended in the paint in a state of being dispersed or dissolved in organic solvents, and in these paint systems, dispersion stability and storage stability The photochromic compound is compounded without causing the above problem.

However, when such a photochromic compound is blended in an aqueous paint, since water is used as a diluent, the photochromic compound cannot be stably dispersed, which poses a problem. Japanese Patent Application Laid-Open No. 2-20575 discloses a water-dispersible coating composition containing a photochromic compound, wherein a photochromic compound having a polymerizable unsaturated functional group is copolymerized with another vinyl monomer. The obtained photochromic polymer fine particles are dispersed in water with a dispersion stabilizer such as polyvinyl alcohol or sodium dodecylbenzene sulfate to prepare a water-dispersible paint. However, since the photochromic polymer fine particles obtained by such a method are those in which the photochromic component is covalently bonded to the polymer side chain, there is a problem that the photochromic property is not sufficiently exhibited. Further, although the dispersion stabilizer is used to disperse it in water, there is a problem that it does not have sufficient dispersion stability and storage stability required as a coating material.

On the other hand, as described above, in recent years, it has been required to diversify the design of the coating appearance and to enhance the appearance quality. For example, in a coating film for automobiles, a new color different from the conventional metallic color or pearl color is required. There is a demand for a coating film having excellent design properties.

An object of the present invention is to satisfy such conventional demands, to provide an aqueous coating composition which is excellent in dispersion stability and storage stability and can be provided with a novel design property, and a color-varying coating film using the same. To provide.

[0007]

The water-based coating composition of the present invention is characterized in that it contains water-dispersible microcapsule particles containing a photochromic substance and a bright pigment dispersed in the water-based coating. I am trying.

Each constituent component of the aqueous coating composition of the present invention will be described below. Microcapsule Particles The microcapsule particles used in the present invention can be formed by a method such as a coacervation method, an interfacial polymerization method, an in situ polymerization method, a liquid curing method, and a liquid drying method.

The microcapsule particles used in the present invention have water dispersibility. In order to impart such water dispersibility to the microcapsule particles, a hydrophilic polymer is used as a wall material of the microcapsule particles. It is preferable to use. When such a hydrophilic polymer wall material is formed by the coacervation method, it is formed by coacervating a concentrated solution phase of the polymer from an aqueous solution of the water-soluble polymer and crosslinking the water-soluble polymer with a curing agent. be able to.

The water-soluble polymer constituting the wall material of the microcapsule particles is not particularly limited as long as it is a water-soluble polymer which can be made water-insoluble by a curing agent, but a gelatin-based polymer is particularly preferable. , A gelatin-arabic gum polymer, a gelatin-carboxymethyl cellulose polymer, and the like can be used. These polymers can be water-insolubilized with aldehydes such as glutaraldehyde, diketones, epoxides, acid anhydrides, acid chlorides, carbodiimides, and inorganic salts.

A photochromic substance is included in the microcapsule particles used in the present invention. Photochromic substances include azobenzenes, spiropyrans,
Spirooxazines, phenothiazines, phenazines, piantrons, anils, metal cytisonates,
Viologen, indigo, fulgide, tetrabenzopentanesene, stilbene, etc. can be mentioned. Among these, photochromic substances of spirooxazines are preferable from the viewpoints of color development and decolorization speeds and repeated durability.

In the present invention, the photochromic substance may be incorporated in the microcapsules in a solution state. In this case, an ultraviolet absorber, an antioxidant, a hindered amine stabilizer, etc. can be dissolved and contained in the solution.

In the case of producing microcapsule particles by the coacervousin method, for example, a solution of a photochromic substance is first mixed with an aqueous solution of a water-soluble polymer to emulsify, and then pH is adjusted or diluted with water, or salt or alcohol is added. It can be produced by causing coacervation and then adding a water-soluble polymer curing agent to crosslink the wall material of the microcapsule particles.

The average particle size of the microcapsule particles used in the present invention is from 1 μm to 50 μm in order to more effectively obtain the color development of multiple colors peculiar to the present invention as described later.
Is preferable, and more preferably 1 μm to 10 μm.
If the average particle size is too small, it may be difficult to obtain multiple color development due to the interaction with the bright pigment as described below. Further, even if the average particle size is too large, interaction with the bright pigment is unlikely to occur, and it may be difficult to obtain multiple color development, and it becomes thicker than the thickness of the coating film and blended in the paint. It becomes an unfavorable material.

Examples of the luster pigment used in the bright pigment present invention, it is possible to use aluminum pigments as used in the metallic paint and the like, scale-like mica powder and the like. As the scale-like mica powder, titanium oxide is coated on the surface so as to exhibit pearl luster, so-called white mica and interfering mica, and titanium oxide and iron oxide are coated, so-called colored mica, etc. Can be used. The pearlescent luster of the flake-like mica powder is said to occur because it transmits and reflects part of the light in the coated titanium oxide layer and also produces coherent light. Therefore, when using the scale-like mica powder as the bright pigment in the present invention, due to various interactions of light with microcapsule particles having incident light and reflected light and photochromic properties in the vicinity of such scale-like mica powder. , It becomes possible to develop a multi-colored color to a higher degree.

Binder for Water-Based Paint The binder used in the water-based paint composition of the present invention is not particularly limited, and examples thereof include acrylic resins and amide group-containing acrylic resins obtained by copolymerizing amide group-containing monomers.
Acrylic / cellulose acetate butyrate mixed resin,
Epoxy resin, alkyd resin, nitrocellulose, polyurethane resin, polyamide resin, epoxy-modified alkyd resin and the like can be used. These resins can be used alone or in combination with a curing agent such as a melamine resin, a urea resin, an isocyanate compound or a blocked isocyanate compound. Among these binder resins, particularly when an amide group-containing acrylic resin is used, a good orientation of the brightening agent can be obtained, so that a coating film having more excellent design can be obtained. The binder resin may be any type of resin that is dried at room temperature or baked.

Amount of Aqueous Coating Composition The content of the microcapsule particles in the aqueous coating composition of the present invention is preferably 1 to 95% by weight in the coating solid content,
More preferably, it is 20 to 70% by weight. When an aluminum pigment is used as the bright pigment, the content of the bright pigment is preferably 0.1 to 40% by weight, and more preferably 0.1 to 15% by weight in the coating solid content. When using the scale-like mica powder as the bright pigment,
0.1-40% by weight is preferable, and more preferably 0.1.
It is 1 to 15% by weight.

Color-Variable Coating Film The color-variable coating film of the present invention is formed by applying the above-mentioned water-based coating composition on the entire surface or a part of an object to be coated.

In one embodiment of a laminated coating film having a color-varying coating film formed on the entire surface of an article to be coated, a color base coating film containing a color pigment formed on the article to be coated and the above aqueous coating composition are provided. The color variable coating film is formed by coating on the color base coating film, and the clear coating film is formed on the color variable coating film.

In one embodiment of the laminated coating film having a color-varying coating film formed by partially coating on the article to be coated, a color base coating film containing a color pigment formed on the article to be coated,
A bright pigment-containing coating containing a bright pigment formed on a color base coating, and a first coating formed on the bright pigment-containing coating.
Clear coating film, a color variable coating film formed by partially applying the above aqueous coating composition on the first clear coating film, and a color variable coating film and the first clear coating film are covered. And a second clear coating film formed on.

[0021]

In the aqueous coating composition of the present invention, the photochromic substance is incorporated into the water-dispersible microcapsule particles. Therefore, in the aqueous coating composition of the present invention, the photochromic substance is stably dispersed,
It is contained in a good dispersed state together with the bright pigment.

In the water-based coating composition of the present invention, the water-dispersible microcapsule particles containing the photochromic substance and the bright pigment are contained in the water-based coating material in a good dispersion state. FIG. 2 is a diagram schematically showing the states of the bright pigment and the microcapsule particles in the coating film when such an aqueous coating composition is used as the coating film. As shown in FIG. 2, bright pigment 1 such as scale-like mica powder
The microcapsule particles 2 are present in the vicinity of. Therefore, the light 3 reflected from the coating film is transmitted through the microcapsule particles 2 and reflected by the bright pigment 1, or is reflected by the bright pigment 1 and then transmitted through the microcapsule particles 2. Etc., the light reflected in various states is included. For this reason, light in various states is reflected due to the three-dimensional relative positional relationship between the glitter pigment 1 and the microcapsule particles 2, and not only the change in glitter due to the glitter pigment and the change in color due to the photochromic substance are caused. , These changes are combined and the multiplexed color is produced. Therefore, according to the present invention,
A coating film having a novel design that has never been seen is formed.

When the scale-like mica powder is used as described above, not only light reflected on the surface of the scale-like mica powder but also light passing through the scale-like mica powder exists. For this reason, the interaction with the microcapsule particles in the vicinity of the scale-like mica powder is further enhanced, and it becomes possible to develop more multiple colors.

In particular, such an interaction between the photochromic substance and the luster pigment is caused by the photochromic substance being encapsulated in the microcapsule particles and being locally or microscopically nonuniformly present in the coating film. That is why such multiple colors can be produced.

[0025]

[Examples] Example 1 [Paint binder (water-soluble amide group-containing acrylic resin)
Preparation] Into a 1-liter reaction vessel equipped with a stirrer, a temperature controller, and a cooling tube was charged 76 parts by weight of ethylene glycol monobutyl ether, and further 15 parts by weight of styrene, 63 parts by weight of methyl methacrylate, and 48 parts by weight of 2-hydroxydiethyl methacrylate. , N-butyl acrylate 1
61 parts by weight of a monomer solution consisting of 17 parts by weight, 27 parts by weight of methacrylic acid, 30 parts by weight of acrylamide and 3 parts by weight of azobisisobutyronitrile were added and stirred, and the temperature was raised to 120 ° C. After adding 245 parts by weight of the above monomer solution over 3 hours, stirring was continued for 1 hour. Furthermore, 28 parts by weight of dimethylethanolamine and 2 parts of ion-exchanged water
00 parts by weight was added to obtain an acrylic resin varnish having a volatile content of 50% by weight and a number average molecular weight of 12,000. The OH value of the obtained resin was 70 and the acid value was 58.

[Preparation of coating composition] The above-mentioned acrylic coating binder solution and a commercially available melamine resin C-703 (manufactured by Mitsui Cyanamid Co., Ltd.) were mixed so as to have resin solid contents of 70% by weight and 30% by weight, respectively, To this, an aqueous dispersion of microcapsule particles containing a spironaphthoxazine-based photochromic compound (trade name PC-7, manufactured by Mitsubishi Kasei Co.) was added as a spironaphthoxazine-based photochromic compound in an amount of 2% by weight, and scale-like mica powder was further added. (White mica, product name "Iriodin 103WI
"I", manufactured by Merck & Co., Inc.) was added so as to be 3% by weight, and the mixture was stirred with a disper to prepare a coating composition. Further, ion-exchanged water was added so that the viscosity of # 4FC at 20 ° C. was 30 seconds.

Comparative Example 1 The above acrylic paint binder solution and a commercially available melamine resin C-703 were contained in a resin solid content of 70% by weight and 3%, respectively.
A coating composition was prepared in the same manner as in Example 1 except that 0% by weight was mixed, and the spironaphthoxazine-based photochromic compound was directly added to 2% by weight.

Evaluation of Dispersion Stability The coating compositions obtained in Example 1 and Comparative Example 1 were allowed to stand at a temperature of 40 ° C. for 10 days to evaluate dispersion stability. As a result, there was no change in the coating composition of Example 1,
The paint properties were also good. On the other hand, in the coating composition of Comparative Example 1, the photochromic compound precipitated and separated.

Example 2 Using the coating composition obtained in Example 1, a laminated coating film as shown in FIG. 1 was formed. In FIG. 1, 11 has shown the to-be-coated article. As the coating object 11, an electrodeposition coating film is formed on a metal plate, and an intermediate coating material (trade name “Olga P-2 Light Gray”, manufactured by Nippon Paint Co., Ltd.) is formed on the electrodeposition coating film. Three
It is coated at 5 μm and baked at 140 ° C. for 20 minutes. A color base paint (trade name “Olga P-2 White”, manufactured by Nippon Paint Co., Ltd.) was applied on the intermediate coating film of the article 11 to a film thickness of 35 μm and 140 ° C.
And baked for 20 minutes to form a color base coating film 12. On this color base coating film 12, the water-based coating composition of Example 1 containing microcapsule particles and scaly mica powder was coated so as to have a film thickness of 12 μm, pre-dried at 60 ° C. for 5 minutes, and then colored. A variable coating film 13 was formed. A clear paint (trade name "Superlac O-150 Clear", manufactured by Nippon Paint Co., Ltd.) is applied on the color-variable coating film 13 so as to have a film thickness of 35 µm, and baked at 140 ° C for 20 minutes to obtain a clear coating film. 14 was formed.

Comparative Example 2 The above-mentioned acrylic paint binder solution of Example 1 and a commercially available melamine resin were contained in a resin solid content of 70% by weight and 3%, respectively.
The microcapsule particle-containing coating material was prepared by mixing so as to be 0% by weight and adding thereto a spironaphthoxazine-based photochromic compound so as to be 2% by weight. Further, in the same mixed liquid of melamine resin and acrylic paint binder, 3% by weight of the same mica as in Example 1 was added.
Were mixed so that a mica-containing paint was prepared.

Using these paints, a laminated coating film as shown in FIG. 5 was formed. In FIG. 5, the article to be coated 31 and the color base coating film 32 were formed in the same manner as the article 11 to be coated and the color base coating film 12 of Example 1 described above. A mica-containing paint is applied on the color base coating film 32 so as to have a film thickness of 12 μm, and dried at 60 ° C. for 5 minutes to form a mica-containing coating film 33. It is coated to a thickness of 12 μm, and after coating, it is dried at 60 ° C. for 5 minutes to form a coating film 34 containing microcapsules.
Was formed. On top of this, the clear coating film 14 of the first embodiment
In the same manner as above, a clear coating film was applied to a film thickness of 35 μm and baked at 140 ° C. for 20 minutes to form a clear coating film 35.
Was formed.

Comparative Example 3 A laminated coating film as shown in FIG. 6 was formed. The coating film forming method was performed in the same manner as in Comparative Example 2 except that the mica-containing coating film 33 was formed on the microcapsule-containing coating film 34 and the stacking order was reversed.

Evaluation of Design Property The design properties of the laminated coating films of Example 2 and Comparative Examples 2 to 4 were evaluated. The design was evaluated by exposing the coating film to sunlight on a sunny day to develop color. The laminated coating film of Comparative Example 3 had a slightly dull change in color compared to the other laminated coating films. Compared with the laminated coating films of Comparative Example 2 and Comparative Example 4, the laminated coating film of Example 2 showed more color change,
Giving different design characteristics.

Example 3 As shown in FIG. 3, a color base coating film 22 and a scale-like mica powder-containing coating film 23 were formed on an object to be coated 21, and a first clear layer 24 was formed thereon. The article to be coated 21 and the color base coating film 22 were formed in the same manner as the article to be coated 11 and the color base coating film 12 of Example 2. The scale-like mica powder-containing coating film 23 was formed in the same manner as the scale-like mica powder-containing coating film 33 of Comparative Example 2. The first clear coating film 24 is
It was formed in the same manner as the clear coating film 14 of Example 2. On the first clear coating film 24, the aqueous coating composition of Example 1 containing microcapsule particles and scaly mica powder was partially applied to form a color-variable coating film 25. The color-variable coating film 25 was formed on a predetermined area of the first clear coating film 24 so as to have ABC characters as shown in FIG. Next, the first clear coating film 24 and the variable color coating film 25.
The second clear coating film 26 was formed so as to have a film thickness of 35 μm so as to cover the film. The second clear coating film 26 was formed by using the same paint as the first clear coating film 24.

When the laminated coating film formed as described above is irradiated with sunlight on a sunny day, the color changes only in the portion where the color-variable coating film 25 is applied, and the characters of ABC which cannot be visually recognized in a dark place. Appears, and a further glittering feeling is obtained, and at the same time, the letters of ABC are colored in a multiplexed color.

As described above, by partially applying the water-based coating composition according to the present invention, it is possible to impart color variability to characters and patterns such as logo marks, and to form characters and patterns. It is also possible to impart an effect such as so-called “brush-out”, in which the material is raised by sunlight irradiation.

[Brief description of drawings]

FIG. 1 is a sectional view showing a laminated coating film according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a mechanism of color change in a coating film formed by the water-based coating composition according to the present invention.

FIG. 3 is a cross-sectional view showing a laminated coating film of another example according to the present invention.

FIG. 4 is a plan view of the laminated coating film shown in FIG.

FIG. 5 is a cross-sectional view showing an example of a comparative laminated coating film.

FIG. 6 is a cross-sectional view showing another example of a comparative laminated coating film.

[Explanation of symbols]

 11, 21 ... Substrate 12, 22 ... Color base coating 13, 25 ... Color variable coating 14, 24, 26 ... Clear coating

Claims (12)

[Claims] 1. A water-based coating composition comprising water-dispersible microcapsule particles containing a photochromic substance and a bright pigment dispersed in the water-based coating. 2. The aqueous coating composition according to claim 1, wherein the photochromic substance is a spirooxazine-based compound. 3. The aqueous coating composition according to claim 1, wherein the photochromic substance is incorporated as a solution. 4. The aqueous coating composition according to claim 3, wherein the solution contains an ultraviolet absorber. 5. The average particle size of the microcapsule particles is 1
The water-based coating composition according to claim 1, which has a thickness of μm to 50 μm. 6. The aqueous coating composition according to claim 1, wherein the bright pigment is scale-like mica powder. 7. The aqueous coating composition according to claim 6, wherein the scale-like mica powder is an interference mica pigment. 8. A color-variable coating film formed by applying the water-based coating composition according to claim 1 on the entire surface of an object to be coated. 9. A color base coating film containing a color pigment formed on an object to be coated, and a color variable coating film formed by applying the aqueous coating composition according to claim 1 on the color base coating film. A color-variable laminated coating film comprising a clear coating film formed on the color-variable coating film. 10. A color-variable coating film formed by partially applying the water-based coating composition according to claim 1 on an object to be coated. 11. A color base coating film containing a color pigment formed on an article to be coated, a bright pigment-containing coating film containing a bright pigment formed on the color base coating film, and a bright pigment-containing coating film on the coating film. A first clear coating film formed on the first clear coating film, a color variable coating film formed by partially applying the aqueous coating composition according to claim 1 on the first clear coating film, and the color variable coating film. A color-variable laminated coating film comprising a film and a second clear coating film formed so as to cover the first clear coating film. 12. The water-based paint according to claim 1, wherein a color base coating film containing a color pigment formed on an article to be coated, and a glitter pigment-containing coating film containing a glitter pigment formed on the color base coating film. A color variable coating film formed by partially applying a composition onto the bright pigment-containing coating film, and a clear coating film formed so as to cover the color variable coating film and the bright pigment-containing coating film. A variable color laminated coating film comprising: