JP7283942B2 - Method for forming retroreflective multi-layer coating - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a multi-layer coating film having both a high-class design property and retroreflectivity.

Retroreflection is an optically special reflection mechanism, and refers to a reflection phenomenon in which incident light returns to the direction of incidence. Unlike specular reflection, in which the angle of incidence and the angle of reflection are equal, the received light is reflected back to the light source as it is, so it has the effect of increasing visibility from the direction of the light source, so it is used for traffic signs and reflective displays of vehicles. there is

In order to obtain a laminated structure that exhibits this retroreflectivity, it is conventionally known to form this retroreflective structure by a painting method. For example, in Patent Literature 1, a metallic coating layer containing a bright pigment as metal fragments obtained by pulverizing a vapor-deposited metal film on a road wheel base material in which a base coating layer is formed of a powder coating, and glass beads A method for forming a glitter coating film is disclosed in which a coating film layer containing and a clear coating film layer are sequentially formed. The retroreflective structure by painting can be easily painted in any shape at a relatively low cost. had to be covered. That is, it has been common practice to incorporate glass beads as a retroreflective material into the retroreflective layer at a high concentration of, for example, 80% by weight or more. The metallic coating usually has a sharp change in luminance depending on the angle (normally, a high value of L* ₁₅ /L* ₇₅ with high flip-flop properties is considered to be good), and the reflective layer is a metallic coating layer. In some cases, the difference in brightness depending on the angle is large, and the obtained multilayer coating film has conspicuous glaring of retroreflected light, and there was a problem in imparting a high-class design property.

Conventionally, as a technique for imparting glittering and luxurious design properties, there have been proposed paint compositions containing luster pigments such as aluminum pigments and pearl pigments, and coating film forming methods thereof. Pearl colors that change the color and brilliance of interfering light are popular from the point of view of luxury. Among them, the white pearl color is attracting attention as a color that combines cleanliness and luxury.

As a method for forming such a white pearl-colored coating film, for example, in Patent Document 2, a white color base coating film, a mica base coating film and a clear coating film are formed on a base material on which an undercoat coating film and an intermediate coating film are formed. are sequentially formed, wherein the mica-based coating comprises the reduced titanium-coated interference mica pigment and the reduced titanium-coated interference mica pigment and the metal oxide-coated pigment in a total mass of A method for forming a white pearl coating film is disclosed, which is characterized by containing a specific amount of

However, there is a problem that the coating film obtained by the method of forming a white pearl coating film has a yellowish tinge as a whole and lacks whiteness.

Therefore, Patent Document 3 discloses a coating composition containing titanium oxide-coated synthetic mica and a vehicle-forming resin, which contains 5 to 20 parts by mass of titanium oxide-coated synthetic mica based on 100 parts by mass of the vehicle-forming resin. A coating composition is proposed in which titanium oxide-coated synthetic mica exhibits specific colorimetric values when a coating film is formed under specific conditions. In the invention disclosed in Patent Document 3, the technique is to suppress the yellowness of the shaded area and improve the whiteness in the highlights. When formed, due to the unique optical characteristics of the beads, the shaded area (diagonal direction) has a yellowish or milky white turbidity. There was a problem of becoming In addition, compared with the case of forming a metallic coating film on the reflective layer, it was thought that the use of interference pigments would not provide the function of retroreflection because the overall luminance is low.

On the other hand, in Patent Document 4, a metal is applied to the surface of glass flakes having a smooth surface in order to form a coating film that not only reflects light when it receives light at night or in a dark place, but also gives a glittering feeling. It discloses a retroluminescent paint containing a scaly pigment on which a film is formed, and the scaly pigment has particles with a particle size of 20 to 80 μm in a proportion of 40% by weight or more. As for the design, since it has little transparency, it does not express glittering interference light with a high-class feeling.

JP-A-2001-79485 JP-A-2006-326538 JP 2018-188660 A JP-A-5-179174

When viewed from all angles, it has a high brightness, a clearer whiteness, and a glittering appearance with a sense of luxury. To provide a method for forming a coating film of a multi-layer coating film having retroreflectivity, capable of obtaining a coating film having both a certain design property and functionality.

As a result of intensive studies to solve the above problems, the present inventors have found that, in a method for forming a multilayer coating film having retroreflectivity, by using a base coating composition containing an interference pigment in the reflective layer, glittering The design has a sense of transparency and a sense of luxury that makes use of the pearly feel, and the transmitted light expressed by the interference pigment and the retroreflected light of the highly refractive beads are additively mixed, and when viewed from all angles, the shade The inventors have also found that a multi-layer coating film having high retroreflectivity in terms of both whiteness and brightness can be obtained in the region, and arrived at the present invention.

That is, the present invention includes the following aspects.

Section 1. Step (1) of forming a base coating film layer (I) as a reflective layer by coating a base coating composition containing an interference pigment (A) on an object to be coated;
Step (2) of applying a retroreflective coating composition containing high refractive index beads to form a retroreflective coating layer (II), then coating at least one layer of a clear coating composition to form a clear coating layer (III) ), wherein the content of the interference pigment (A) in the base coating composition is equal to the resin solid content of the base coating composition A method for forming a multilayer coating film having retroreflectivity, characterized in that the content is in the range of 1 to 20 parts by mass based on 100 parts by mass.

Section 2. Item 1. The retroreflective coating having retroreflective properties according to Item 1, wherein in the step (2), the retroreflective coating composition is spray-coated on the uncured base coating film to form the retroreflective layer (II). A method for forming a multilayer coating film.

Item 3. Item 1 or 2, wherein the light transmittance at a wavelength of 400 to 700 nm is in the range of 10 to 99% in the coating film obtained by coating the base coating composition so as to form a cured coating film having a thickness of 15 μm. A method for forming a multilayer coating film having retroreflectivity according to 1.

The resulting multi-layer coating film has little angle dependence and high brightness when viewed from all directions. At night, it exhibits light retroreflectivity with high brightness, and a coating film having both design and functionality can be obtained.

In addition, since the adhesion between the base coating layer (I) and the retroreflective coating layer (II) is excellent, it is possible to apply a topcoat without dropping the high refractive index beads, and a clear topcoat can be applied. It also has excellent adhesion to the film layer (III) and excellent weather resistance.

<<Method for Forming Multilayer Coating Film Having Retroreflectivity>>
The method for forming a multilayer coating film having retroreflective properties according to the present invention comprises coating a base coating composition containing an interference pigment (A) on an object to be coated, and using the base coating layer (I) as a reflective layer. step (1) of forming, step (2) of coating a retroreflective coating composition containing high refractive index beads to form a retroreflective coating layer (II), and then coating at least one layer of a clear coating composition. and step (3) of forming a clear coating layer (III) in this order, wherein the content of the interference pigment (A) in the base coating composition is It is characterized by being in the range of 1 to 20 parts by mass based on 100 parts by mass of the resin solid content of the coating composition.

<Subject to be coated>
The object to be coated is not particularly limited, and examples include vehicle bodies such as automobiles, motorcycles, railroads, bicycles, tricycles, and unicycles, and parts thereof, and other vehicle or light vehicle-related members; roads such as soundproof walls, tunnel interior panels, and guardrails. Peripheral materials; housing materials such as siding materials, tiles, glass, sashes, screen doors, gates, carports, sunrooms, veranda materials, roof materials, housing exterior wall materials, bathroom mirrors, bathroom walls, bathtubs, cosmetic mirrors, sanitary ware, etc. Members; store-related members such as show windows, refrigerated product cases, and frozen product cases; home electric appliances such as mobile phones, audio equipment, personal computers, and the like.

The material of the base material of these objects to be coated is not particularly limited. - Fe, etc.) metal materials such as plated steel; resins such as polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin, etc. plastic materials such as FRP; inorganic materials such as glass, cement, concrete; wood; fiber materials (paper, cloth, etc.). Among them, at least one selected from metal materials and plastic materials is preferable. These materials may be in the form of a flat plate or molded into a desired shape.

The color of the object to be coated is not particularly limited, but in particular when the coating film is a white pearl color, an undercoat or intermediate coating film, a colored base coating film, or the like may be formed on the object to be coated. It is preferable that the coating film of the object to be coated before forming the base coating layer (I), that is, the coating color of the colored base coating film is white from the viewpoint of improving the luminance of retroreflected light.

<Step (1) of forming the base coating layer (I) as a reflective layer>
The method for forming a multilayer coating film of the present invention comprises the step (1) of forming the base coating film layer (I) as a reflective layer by applying a base coating composition containing an interference pigment (A), The content of the interference pigment (A) in the base coating composition is in the range of 1 to 20 parts by mass, preferably in the range of 2 to 18 parts by mass based on 100 parts by mass of the resin solid content of the base coating composition. be.

Interference colors are caused by a phenomenon in which, when light is reflected by a certain substance, a phase difference occurs in the reflected light, and a specific wavelength is strengthened or weakened. Pigments having such effects are called interference pigments, pearl luster pigments or pearl pigments, and are commercially available from various companies.

Specifically, for example, an interference pigment is a pigment having a layer structure of at least one layer, in which mica, glass flakes, or the like are coated with a metal oxide such as titanium oxide to form a layer. Commercially available products include metal oxide-coated mica such as titanium oxide-coated interference mica pigments, metal oxide-coated alumina flakes, and metal oxide-coated glass flakes.

The interference pigment (A) used in the present method is preferably metal oxide-coated mica and/or metal oxide-coated glass flakes, particularly preferably titanium oxide-coated synthesis, from the viewpoint of obtaining retroreflected light with high transparency and brightness. It is mica.

The mica with which the metal oxide-coated mica is coated can be either natural or synthetic. As the metal oxide to be coated, at least one oxide selected from titanium, iron, chromium, cobalt, tin and zirconium is preferable, and titanium oxide is particularly preferable because it is inexpensive.

Further, synthetic mica is particularly preferable because it contains less impurities and less yellowness than natural mica, and is relatively uniform in size and thickness.

Synthetic mica is a phyllosilicate obtained by mixing compounds containing potassium, sodium, magnesium, aluminum, silicon, fluorine, etc. in a certain ratio, melting, crystallizing, cooling, and then mechanically pulverizing. Minerals. Such as, for example,
_KMg3 ( _AlSi3O10 ) _F2 : potassium phlogopite _,
KMg21 _{/2 ( Si4O10} ) _F2 : potassium _tetrasilicon mica,
_KMg2Li ( _Si4O10 ) _F2 : potassium teniolite _,
NaMg3 ( _AlSi3O10 ) _F2 : sodium phlogopite _,
NaMg2Li ( _Si4O10 ) _F2 : sodium teniolite _,
NaMg21 _{/2 ( Si4O10} ) _F2 : sodium _tetrasilicon mica,
Na1 _{/3Mg22 / 3Li1 / 3} ( _Si4O10 ) _F2 : sodium hectorite and the like. These can be used alone or in combination of two or more.

The interference light and transmitted light expressed by the interference pigment (A) and the reflected light peculiar to the high-refractive-index beads are additively mixed to improve the luminance, design property, and retroreflectivity. By this method, the base coating composition functions as a reflective layer, and when the high refractive index bead layer described later is formed, a multilayer coating film having retroreflection that achieves both designability and high brightness retroreflection is obtained. can be formed.

The interference pigment (A) may be coated with titanium oxide and then subjected to a surface treatment to improve dispersibility, water resistance, chemical resistance, weather resistance, and the like.

The types of interference colors of the interference pigments include silver, gold, red, purple, blue, green and the like, and it is more preferable to use interference pigments having a golden interference color. In the present invention, the term "interference color" refers to the color tone of reflected interference light of structural coloration possessed by an interference pigment.

The content of the interference pigment (A) is 1 to 20 parts by mass, preferably 2 to 18 parts by mass, based on 100 parts by mass of the resin solid content of the base coating composition, from the viewpoint of design. It is preferable that

Among these, the content when containing an interference pigment having a golden interference color is 1 to 10 parts by mass with respect to 100 parts by mass of the resin solid content of the base paint composition, from the viewpoint of retroreflectivity and designability. parts, preferably 2 to 8 parts by mass.

The vehicle-forming resin (b) used in the base paint composition may contain a resin and a curing agent that are generally used as film-forming resins. Coating film-forming resins such as resins, polyester resins, and epoxy resins can be used.

The base coating composition may further contain additives such as other coloring pigments, extender pigments, and bright pigments other than the above (A), polymer fine particles, etc., as additives, as long as they do not impair the transparency and design properties. Control agents, plasticizers, dispersants, and diluents such as organic solvents may be included. On the other hand, 20 parts by mass or less, preferably in the range of 0.01 to 10 parts by mass is suitable.

In the present invention, the base coating layer is transparent, and the term "transparent" includes translucence. do not hide). Specifically, in the base coating film obtained by coating so as to have a thickness of 15 μm as a cured coating film, the light transmittance at a wavelength of 400 to 700 nm is usually 10 to 99%, preferably 70 to 98%. More preferably, it is within the range of 80 to 95%, since the transparency and high-grade appearance of the multilayer coating film can be maintained.

The base coating composition can be applied by, for example, spray coating using an air spray, airless spray, or rotary atomization coating machine, and static electricity may be applied during coating.

The coating film thickness of the base coating film is usually within the range of 5 to 40 μm, preferably 8 to 30 μm, more preferably 10 to 20 μm, in terms of adhesion to the retroreflective coating layer and design. be able to.

<Step (2) of forming retroreflective coating layer (II)>
Next, a retroreflective coating composition containing high refractive index beads is applied onto the base coating layer (I) obtained in step (1) to form a retroreflective coating layer (II).

The cured state of the base coating film (I) may be either cured or uncured. From the viewpoint of design and retroreflectivity, a retroreflective coating composition is spray-coated on the uncured base coating film. to form the retroreflective coating layer (II).

Coating on the uncured coating film is sometimes called wet-on-wet. Wet-on-wet refers to painting in a state in which the coating film is not substantially cured. It is a state that has not reached the following cured and dried state, and includes a dry to the touch state and a semi-cured and dry state defined in JIS K 5600-1-1. The cured coating film is a cured and dried state specified in JIS K 5600-1-1 (2004), that is, the center of the coated surface is strongly pinched between the thumb and index finger, and the coated surface does not have dents due to fingerprints. The movement of the paint film is not felt, and the paint film is in a state where the center of the paint surface is repeatedly rubbed rapidly with a fingertip, leaving no scratches on the paint surface.

When the retroreflective coating composition of the present invention is applied to an uncured base coating film, the high refractive index beads are easily embedded in the base coating film layer due to the spray pressure during spray coating, and at the same time, the uncured base coating film Since it becomes easy to orientate the luster pigment inside so as to surround the high refractive index beads, it is particularly preferable because it has the effect of effectively exhibiting retroreflection.
Examples of retroreflective coating compositions include coating compositions containing bead (spherical) particles exhibiting a high refractive index as materials capable of exhibiting a retroreflective mechanism and a vehicle-forming resin composition. In the present specification, the bead-like (spherical) particles exhibiting a high refractive index are hereinafter referred to as "high refractive index beads". Specifically, the refractive index is 1.5 or more, particularly 1.8 or more, more preferably 2.0 or more, and particularly preferably in the range of 2.1 to 2.3. From the viewpoint of retroreflection efficiency (light transmittance), glass beads are preferably used rather than resin beads.

The average particle diameter (D50) of the high refractive index beads is preferably in the range of about 5 to 100 μm, more preferably in the range of 10 to 60 μm, particularly in the range of 30 to 50 μm. Further, in order to produce a better interference effect in the reflected light, the particle size distribution of the high refractive index beads is preferably as narrow and sharp as possible, and the particle size distribution contains 80% by weight or more of particles having a particle size of 25 to 60 μm. is particularly preferably used.

The content of the high refractive index beads is not particularly limited as long as retroreflectivity can be obtained. From the viewpoint of compatibility between retroreflectivity and design, it is preferably in the range of 10 to 150 parts by mass.

The vehicle-forming resin composition is not particularly limited, and may contain a resin and a curing agent generally used as a film-forming resin (sometimes referred to as a vehicle-forming resin). , acrylic resins, polyamide resins, urethane resins, polyester resins, and epoxy resins. The coating film-forming resin preferably contains a hydroxyl group for cross-linking with a curing agent. Polyisocyanate compounds represented by hexamethylene diisocyanate (HMDI) or dimers or trimers thereof; Polyisocyanate compounds and polyhydric alcohols, low-molecular-weight polyester resins, water, etc. are urethane-formed under conditions in which isocyanate groups are excessive. A prepolymer obtained by a reaction, etc., may be mentioned. Moreover, the isocyanate group of the above polyisocyanate compound blocked with a blocking agent can also be used. Examples of blocking agents include phenols; oximes; lactams; alcohols; mercaptans; and active methylene compounds such as diethyl malonate. When using a blocked polyisocyanate compound, it is preferable to use a dissociation catalyst for the blocking agent together. These can be used individually by 1 type or in combination of 2 or more types.

The retroreflective coating composition can be applied by, for example, spray coating using an air spray, an airless spray, or a rotary atomizing coating machine, and static electricity may be applied during coating.

The coating thickness of the retroreflective coating is usually within the range of 5 to 40 μm, preferably 10 to 30 μm, more preferably 12 to 20 μm, in terms of adhesion to the base coating layer and design. can do.

The retroreflective coating layer (II) itself can be cured by heating at a temperature of about 100 to 180°C. By arranging the retroreflective material uniformly in a single layer and arranging it in the vicinity of the base layer, it is possible to exhibit a glittering, high-class and excellent design.

As preheating under the heating conditions, preheating, air blowing, or the like may be performed. The preheating temperature is preferably about 40 to 100°C, more preferably about 50 to 90°C, and even more preferably about 60 to 80°C. The preheating time is preferably about 30 seconds to 15 minutes, more preferably about 1 to 10 minutes, and even more preferably about 2 to 5 minutes. The air blowing can usually be carried out by blowing air heated to normal temperature or about 25° C. to 80° C. for about 30 seconds to 15 minutes to the coated surface of the object to be coated.

The baking temperature is usually in the range of 100 to 180°C, preferably 110 to 160°C. Also, the baking treatment time is preferably 10 to 60 minutes.

<Step (3) of forming clear coating layer (III)>
Next, the at least one clear coating layer is formed on the retroreflective coating layer (II) obtained in step (2).

As the clear coating composition of the present invention, conventionally known compositions can be used without limitation. For example, a liquid or powder coating composition containing a base resin and a cross-linking agent can be applied. Examples of base resins include acrylic resins, polyester resins, alkyd resins, fluororesins, urethane resins, silicon-containing resins, etc. containing crosslinkable functional groups such as hydroxyl groups, carboxyl groups, silanol groups and epoxy groups. Examples of cross-linking agents include melamine resins, urea resins, polyisocyanate compounds, blocked polyisocyanate compounds, epoxy compounds or resins, carboxyl group-containing compounds or resins, acid anhydrides, and alkoxysilane group-containing compounds that can react with the functional groups of the base resin. compounds or resins; These can be used individually by 1 type or in combination of 2 or more types.
In addition, if necessary, solvents such as water and organic solvents, curing catalysts, antifoaming agents, ultraviolet absorbents and other additives may be added as appropriate.

Coloring pigments can be appropriately added to the clear coating composition of the present invention within a range that does not impair the transparency. As the color pigment, conventionally known pigments for inks and paints can be blended singly or in combination of two or more. The amount to be added may be appropriately determined, but is 30 parts by weight or less, preferably 0.1 to 10 parts by weight, per 100 parts by weight of the film-forming resin composition in the clear coating composition.

The clear coating composition can be applied by, for example, spray coating using an air spray, airless spray, or rotary atomization coating machine, and static electricity may be applied during coating.

From the standpoint of preventing the retroreflective material from falling off and achieving uniformity in design, the coating thickness of the clear coating film is desirably enough to cover the retroreflective material. It can be in the range of 10-45 μm.

In the present invention, when the clear coating composition is applied without heat-curing the coating film of the base coating composition and/or the retroreflective coating composition, these coating films are applied after the clear coating composition is applied. may be heat cured at the same time. The coating film of the clear coating composition itself can be crosslinked and cured at a temperature of about 70 to about 150°C.

The multilayer coating film having retroreflectivity obtained by the method of the present invention provides a coating film with a high degree of whiteness and brightness from any angle, such as highlights and shades, and an excellent appearance with a dense feeling. .

In particular, the L*a*b* colorimetry obtained using a multi-angle spectrophotometer (trade name “MA-68II”) may differ slightly depending on the optical properties of the high-refractive-index beads employed. The value of the system can be used to evaluate luminance and whiteness.

In the present invention, the luminance in the shaded area is measured using a multi-angle spectrophotometer (trade name "MA-68II") according to the method of JIS Z 8729 (2004), and the light receiving angle is 75 degrees. was evaluated by the L* value of , i.e., the "L* ₇₅ value". Specifically, measurement light was irradiated at an angle of 45° with respect to an axis perpendicular to the measurement target surface, and L* was measured for light received at an angle of 75° from the regular reflection angle in the direction of the measurement light. The larger the L* ₇₅ value, the higher the lightness of the resulting coating film and the more excellent the brightness.

The L* ₇₅ value of the retroreflective multi-layer coating film obtained from the present invention is in the range of 95 to 120, preferably in the range of 100 to 110. It is particularly preferable from the viewpoint of compatibility.

The whiteness of the shaded area can also be quantified by the yellowness of the shaded area. The yellowness of the shaded area was measured using a multi-angle spectrophotometer (trade name "MA-68II") according to the method of JIS Z 8729 (2004), and the a* value at an acceptance angle of 75 degrees, that is, It is also represented by the “b* ₇₅ value” in the L*a*b* color system. It means that the smaller the b* ₇₅ value, the less the yellowness and the better the whiteness of the obtained coating film (higher whiteness).

The b* ₇₅ value of the retroreflective multilayer coating film obtained from the present invention is 3.5 or less, preferably in the range of 1.0 to 3.0. It is particularly preferable from the viewpoint of generating light.

The flip-flop value (FF value) represents the change in brightness due to the observation angle of the painted surface, and is calculated below using the L* value at a light receiving angle of 15 degrees in the highlight area and the L* value at a light receiving angle of 75 degrees in the shade area. It is a value calculated by the formula (1). Here, the L* value is the L* value in the L*a*b* color system defined in JIS Z 8729 (2004).

FF value = L* ₁₅ /L* ₇₅ (1)
The closer the FF value is to 1, the less extreme the lightness change from shade to highlight is and the more uniform the FF value is within 1.00±0.2, preferably within 1.00±0.15. is particularly suitable from the viewpoint of achieving both designability and visibility of retroreflection.

Also, as an indicator of the degree of angular dependence of luminance, a light-receiving angle of 15 measured according to the method of JIS Z 8729 (2004) using a multi-angle spectrophotometer (trade name “MA-68II”), The standard deviation of the L* values at 25, 45, 75, 110 degrees and 5 angles was determined. If the value is close to 1.0, it indicates that the brightness (brightness) varies less with angle. The range of the standard deviation of the L* value obtained by the present invention is less than 6, preferably within the range of 1-5.

The present invention will be described in more detail below with reference to examples. "Parts" and "%" indicate "mass parts" and "mass%" unless otherwise specified.

Production example 1
15 parts of the interference pigment a (*1) per 100 parts by mass (solid content) of a vehicle-forming resin composition comprising 75 parts of a hydroxyl group-containing acrylic resin (hydroxyl value: 100, number average molecular weight: 20,000) and 25 parts of a melamine resin. The organic solvent type base paint composition No. 1 was adjusted.

Production example 2
In Production Example 1, organic solvent-based base paint composition No. . 2 was adjusted.

Production example 3
Organic solvent-based base paint composition No. 1 was prepared in the same manner as in Production Example 1 except that 0.65 parts of silver pigment (*3) was used as the interference pigment. 3 was adjusted.

Production example 4
Organic solvent type base coating composition No. 1 was prepared in the same manner as in Production Example 1 except that 15 parts of blue pigment (*4) was used as the interference pigment. 4 was adjusted.

Production example 5
Degreased and zinc phosphate treated steel plate (JIS G3141, size 400 x 300 x 0.8 mm) cationic electrodeposition paint "Electron 9400HB" (trade name: manufactured by Kansai Paint Co., Ltd., amine-modified epoxy resin cationic resin with curing agent A block polyisocyanate compound was used as a cured coating film) was electrodeposited on the cured coating film so as to have a film thickness of 20 μm, and was crosslinked and cured by heating at 170° C. for 20 minutes to obtain an electrodeposition coating film. Furthermore, an intermediate paint "Rugabake" (trade name: Kansai Paint Co., Ltd., polyester resin/melamine resin organic solvent type paint, lightness L* ₁₅ value: 60) was applied to the resulting electrodeposition coated surface. Based on the cured coating film, the cured coating film was coated with a spray so as to have a film thickness of 30 μm, and was crosslinked and cured by heating at 140° C. for 30 minutes to form an intermediate coating film. On the resulting intermediate coating film, a white base paint "Magiclon 5600" (trade name: Kansai Paint Co., Ltd., acrylic and melamine solvent paint) was diluted with an organic solvent to adjust the solid content to 25% by mass. Using a type rotary electrostatic coating machine, coating was performed at a booth temperature of 20° C. and humidity of 75% so that the cured coating film would have a film thickness of 15 μm. After coating, the coating was allowed to stand at room temperature for 15 minutes and then heated at 140° C. for 30 minutes in a hot air circulating drying oven to obtain a cured coating film having a thickness of 30 μm. The resulting coated plate was designated as object 1 to be coated. The coating color of the object to be coated 1 is white, and the values of L*a*b* at 15 degrees measured using a multi-angle spectrophotometer (trade name “MA-68II”) are the lightness L * ₁₅ value: 98, reddish a* ₁₅ value -1.0, yellowish b* ₁₅ value: 1.2.

Examples 1 and 2, Comparative Examples 1 and 2
Each base paint composition No. 1 prepared as described above was applied onto the article to be coated 1 obtained in Production Example 5 above. 1 to No. 4 was diluted with an organic solvent to adjust the solid content to 25% by mass, and using a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.), the booth temperature was 20 ° C., the humidity was 75%, and the discharge pressure was 2.5 kgf / cm. ^2. Coating was performed at a gun distance of 20 cm so that the cured coating film had a thickness of 15 μm. After that, it was allowed to stand at room temperature for 15 minutes, and then a retroreflective coating composition (Note 1) containing high refractive index beads was applied to these uncured coated surfaces with a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.). was used to coat under conditions of a booth temperature of 20° C., a humidity of 75%, a discharge pressure of 2.5 kgf/cm ² and a gun distance of 20 cm so that the cured coating film would have a thickness of 15 μm. After that, it was dried and cured by heating at 140° C. for 30 minutes in a hot air circulating drying oven. Furthermore, clear paint "Magiclon 7100" (trade name: Kansai Paint Co., Ltd., acrylic/melamine solvent paint) was applied using a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.) at a booth temperature of 20 ° C. and humidity of 75%. The cured coating film was coated so as to have a film thickness of 25 to 35 μm under the conditions of . After coating, the coating was allowed to stand at room temperature for 15 minutes, then heated at 140° C. for 30 minutes in a hot air circulating drying oven to dry and cure to obtain a multi-layer coating film. Various evaluations were carried out using the coated plate having the obtained multi-layer coating film as a test plate.

Incidentally, the base paint composition No. 1 to No. A free coating film was prepared by coating 4 so as to have a thickness of 15 μm as a cured coating film, and the light transmittance at a wavelength of 400 to 700 nm was measured. light transmittance] is based on the base paint composition No. 1 (92%), base paint composition no. 2 (91%), base paint composition no. 3 (70%), base paint composition no. 4 (30%).

(Note 1) Retroreflective paint composition: Magiclon 1026 Clear (manufactured by Kansai Paint Co., Ltd., trade name, acrylic/melamine curable resin paint) Unibeads UB-02M (BaO-SiO ₂ - TiO ₂ -based glass beads, refractive index 1.93, specific gravity 4.2, manufactured by Union Co., Ltd.) 100 parts, diluted with an organic solvent (butyl acetate) to a solid content of 40% by mass, retroreflective coating composition got

Comparative example 3
A retroreflective coating composition (Note 1) containing high refractive index beads is applied onto the object to be coated 1 obtained in Production Example 5 using a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.) in a booth. The cured coating film was coated to a thickness of 15 μm under conditions of a temperature of 20° C., a humidity of 75%, a discharge pressure of 2.5 kgf/cm ² and a gun distance of 20 cm. After that, it was dried and cured by heating at 140° C. for 30 minutes in a hot air circulating drying oven. Furthermore, clear paint "Magiclon 7100" (trade name: Kansai Paint Co., Ltd., acrylic/melamine solvent paint) was applied using a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.) at a booth temperature of 20 ° C. and humidity of 75%. The cured coating film was coated under the conditions of 25 to 35 μm in thickness. After coating, the coating was allowed to stand at room temperature for 15 minutes, then heated at 140° C. for 30 minutes in a hot air circulating drying oven to dry and cure to obtain a multi-layer coating film. Various evaluations were carried out using the coated plate having the obtained multi-layer coating film as a test plate.

Comparative Examples 5-7
Each base paint composition No. 1 prepared as described above was applied onto the article to be coated 1 obtained in Production Example 5 above. 1 to No. 4 was diluted with an organic solvent to adjust the solid content to 25% by mass, and using a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.), the booth temperature was 20 ° C., the humidity was 75%, and the discharge pressure was 2.5 kgf / cm. ^2. Coating was performed at a gun distance of 20 cm so that the cured coating film had a thickness of 15 μm. After that, it was left at room temperature for 15 minutes, and without applying the retroreflective paint composition, a clear paint composition "Magiclon 7100" (trade name: Kansai Paint Co., Ltd., acrylic/melamine solvent paint) was applied with a small spray gun (Anest). W-101 manufactured by Iwata Co., Ltd.) was used to coat under the conditions of a booth temperature of 20° C. and a humidity of 75% so that the cured coating film would have a thickness of 25 to 35 μm. After coating, the coating was allowed to stand at room temperature for 15 minutes, then heated at 140° C. for 30 minutes in a hot air circulating drying oven to dry and cure to obtain a multi-layer coating film. Various evaluations were carried out using the coated plate having the obtained multi-layer coating film as a test plate.

Comparative example 8
A clear coating composition "Magiclon 7100" (trade name: Kansai Paint Co., Ltd., acrylic/melamine-based solvent paint) was applied onto the object to be coated 1 obtained in Production Example 5 without applying the retroreflective coating composition. Using a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.), coating was performed at a booth temperature of 20° C. and a humidity of 75% so that the cured coating film had a thickness of 25 to 35 μm. After coating, the coating was allowed to stand at room temperature for 15 minutes, then heated at 140° C. for 30 minutes in a hot air circulating drying oven to dry and cure to obtain a multi-layer coating film. Various evaluations were carried out using the coated plate having the obtained multi-layer coating film as a test plate.

表１及び製造例１～４に記載の顔料成分は下記のとおり。

The pigment components described in Table 1 and Production Examples 1 to 4 are as follows.

A multi-angle spectrophotometer (trade name “MA-68II”) was used as a colorimeter.

(*1) Interference pigment a: synthetic mica, titanium oxide-coated pigment, median diameter D50 (μm) = about 21 μm, appearance fair, interference color (silver), transmitted light (yellow),
(*2) Interference pigment b: synthetic mica, titanium oxide-coated pigment, median diameter D50 (μm) = about 22 μm, appearance fair, interference color (gold), transmitted light (blue),
(*3) Silver pigment: aluminum paste 1109M, trade name, manufactured by Toyo Aluminum Co., Ltd., aluminum pigment, average particle size 34.6 μm,
(*4) Blue pigment: copper phthalocyanine blue, reflected light (blue).
Various test items are as follows.

Test item 1: Finish (appearance in shade direction)
The prepared coated plate was illuminated with an artificial sun lamp (manufactured by SERIC, color temperature 6500K), and observed by changing the angle of the test plate with respect to the illumination. The finish, such as rough feeling, was visually observed, and the finish was evaluated according to the following criteria.
A: Good shade with no turbidity, yellowness, dust/bubbles, etc. B: Shade with slight cloudiness, yellowness, or dust/bubbles observed C: Shade with cloudiness, yellowness, or dust/bubbles Is recognized.

Test item 2: luxury feeling (shiny feeling (glittering feeling))
The prepared coated plate is illuminated with an artificial sun lamp (manufactured by Seric, color temperature 6500K), and the angle of the test plate to the illumination is changed to observe the transparency and the sense of brightness (luxury) for visual observation. evaluated.
A: Very good, with a strong sense of glittering pearl brilliance across a wide range from highlights to shades.
B: Good;
C: From highlights to shades, the glittering pearly luster is weak or uneven.
D: From highlights to shades, almost no glittering pearly luster is observed.

Test Item 3: Retroreflectivity The degree of retroreflectivity of the obtained coating film was visually observed and evaluated. A 10 cm x 15 cm coated test panel was irradiated with light from a vertical position of 3 m in a dark room (during the daytime, with blinds or the like blocking external light and turning off the lights in the room) with a flashlight. The coating film surface at this time was observed with the naked eye at a position with an angle of 5 degrees from the light source (3 m away from the coating test plate), and evaluated according to the following criteria.
A: The retroreflection is strong and can be clearly recognized with the naked eye.
B: A level at which no retroreflection can be recognized and there is no problem in use,
C: Although retroreflection can be recognized, it is slightly weak or uneven.
D: retroreflection can be faintly recognized,
E: No retroreflection at all.

If even one of the test items 1 to 3 has the lowest evaluation (C, D, or E), the product has a problem and fails as a comprehensive evaluation.

Claims (3)

Metal oxide-coated mica and/or metal on an object to be coated, including the body of a vehicle or light vehicle, or a part of the vehicle or light vehicle, wherein the coating film color of the object to be coated is white Step (1) of applying a base coating composition containing an interference pigment (A) containing oxide-coated glass flakes to form a base coating layer (I) as a reflective layer;
step (2) of applying a retroreflective coating composition containing high refractive index beads to form a retroreflective coating layer (II);
Step (3) of applying at least one layer of the clear coating composition to form a clear coating layer (III);
A method for forming a multilayer coating film comprising in this order,
The content of the interference pigment (A) in the base coating composition is in the range of 1 to 20 parts by mass based on 100 parts by mass of the resin solid content of the base coating composition. A method for forming a multilayer coating film having. 2. The retroreflective coating according to claim 1, wherein in step (2), the retroreflective coating composition is spray-coated onto the uncured base coating to form the retroreflective coating layer (II). A method for forming a multi-layer coating film having properties. The light transmittance of a coating film obtained by coating the base coating composition to a thickness of 15 μm as a cured coating film at a wavelength of 400 to 700 nm is in the range of 10 to 99% or 3. The method for forming a retroreflective multi-layer coating film according to 2 above.