JP2009183885A - Method for forming multilayer coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid color coating film which has a flip flop property. <P>SOLUTION: The multilayer coating film includes a reflective film having specular reflection and a color pigment-containing coating film on a base material in order. 15°L* value of the multilayer coating film is 50 or more and 75°L* value thereof is 30 or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer coating film having a flip-flop property (a design in which hue and brightness change depending on an angle is referred to as a flip-flop property and may be abbreviated as FF property hereinafter) and the multilayer coating material. The present invention relates to a film forming method.

  In recent years, in fields requiring high design properties such as automobile bodies and automobile parts, for example, in order to emphasize complicated press lines of automobile bodies, a glittering material-containing paint (so-called metallic paint) having a metallic particle feeling is used. It is preferably used. In recent years, the use of solid color paints (paints that can produce a coating without a metallic particle feeling) tends to obscure the contours of complex shapes with high design properties, so their use has decreased. .

  In addition, paints that can provide a plating-like appearance (that is, an appearance having a metallic luster) are preferably used for automobile parts such as aluminum wheels in order to make the high design quality stand out and give a higher-class feeling. (For example, refer to Patent Document 1).

  Furthermore, a paint for forming a glossy film that gives a mirror film or a half mirror film is disclosed, and it is described that it can be applied to automobiles and the like (for example, see Patent Document 2).

As described above, in this field, paints that give a metal feeling are preferably used to emphasize high designability. However, in order to further stimulate consumers' desire to purchase, conventional paints and paints are used. Development of a new paint color that cannot be obtained by the method, for example, a solid color having flip-flop property, is desired.
JP 2006-169269 A JP 2006-124583 A

  An object of the present invention is to provide a solid color coating film having flip-flop properties.

  As a result of intensive studies in view of the above-mentioned problems, the present inventors have found that when forming a color pigment-containing coating film on a reflective film having specular reflection, the film thickness of the color pigment-containing coating film is a film thickness necessary for concealing the base. It was found that a solid color multilayer coating film having a flip-flop effect can be obtained by setting the ratio to 60% to less than 100%. Accordingly, the present invention provides the following.

  A multilayer coating film comprising a reflective film having a specular reflection and a colored pigment-containing coating film on a substrate, the 15-degree L * value of the multilayer coating film being 50 or more, and 75-degree L * Multilayer coating film characterized by having a value of 30 or less.

  The multilayer coating film having a flip-flop value of 2 or more.

  The multilayer coating film comprising a clear coating film on the colored pigment-containing coating film.

Step (1) of applying a metal particle-containing coating composition on a substrate to form a reflective film having specular reflection, and applying a coloring pigment-containing coating composition on the reflective film obtained in the step (1) A method for forming a multilayer coating film comprising the step (2) of forming a colored pigment-containing coating film,
The film thickness required for concealing the base of the color pigment-containing coating film is 12 to 100 μm,
The film thickness of the color pigment-containing coating film obtained in the step (2) is 60% to less than 100% of the film thickness necessary for the base concealment, and
A multilayer coating film forming method, wherein the obtained multilayer coating film has a 15 degree L * value of 50 or more and a 75 degree L * value of 30 or less.

  The method for forming a multilayer coating film as described above, wherein the flip-flop value is 2 or more.

  The method for forming a multilayer coating film, wherein the content of the color pigment contained in the color pigment-containing coating composition is 0.01 to 18% by mass.

  Furthermore, the said multilayer coating-film formation method including the process (3) of apply | coating a clear coating composition on the coloring pigment containing coating film obtained at the said process (2), and forming a clear coating film.

  According to the present invention, flip-flop properties (that is, a coating-like appearance including a glittering material) can be obtained simply by forming a coating film containing a specific color pigment on a reflective film having specular reflection. The color pigment-containing coating film is a coating film called a so-called solid color coating film, and does not include a bright material such as a bright pigment and includes only a color pigment. Such a so-called solid color coating film is in a state in which light transmittance is ensured to some extent on the reflective film made of the metal particle-containing coating composition (that is, less than 60% to less than 100% of the film thickness necessary for hiding the base). By forming the film with a film thickness, the metallic luster of the lower reflective film appears on the surface, and a mysterious metallic luster appearance that has never existed can be obtained. This metallic luster appearance can only be expressed using the term flip-flop property, but a metallic luster appearance with a taste different from a coating film containing a conventional glittering material can be obtained. In addition, by changing the light transmittance of the solid color coating on the reflective film, the degree to which the metallic luster appearance can be visually recognized on the surface of the multilayer coating film and the angle at which the metallic luster appearance can be visually recognized change. It is possible to selectively provide a coating film appearance having a different taste from the glittering material-containing coating film whose gloss appearance is exposed on the surface.

Multi-layer coating film The multi-layer coating film of the present invention is a multi-layer coating film comprising a reflective film having a specular reflection and a colored pigment-containing coating film on a base material in order. * Value is 50 or more, and 75 degree L * value is 30 or less.

(1. Base material)
The substrate is not particularly limited, and examples thereof include metals such as iron, steel, aluminum, magnesium, copper, and alloys thereof (which may be subjected to chemical conversion treatment); inorganic materials such as glass, cement, and concrete; polyethylene Resin, polypropylene resin, ethylene-vinyl acetate copolymer resin, polyamide resin, acrylic resin, vinylidene chloride resin, vinyl chloride resin, polycarbonate resin, polyurethane resin, polyethylene terephthalate resin, epoxy resin, ABS resin, AS resin, polystyrene resin, Examples thereof include various synthetic resin materials such as polymethylmethine resin and FRP; natural or synthetic materials such as fiber materials such as wood, paper and cloth. The base material of the present invention is preferably an automobile body made of iron (alloy), or an automobile plastic constituting an automobile body and an automobile part, and includes a member to which these are bonded.

  In addition, the base material may include an undercoat film (for example, an anion or cation electrodeposition film in the case of a metal substrate) and / or an intermediate coat film well known by those skilled in the art.

(2. Reflective film having specular reflection)
The reflective film constituting the multilayer coating film of the present invention is a reflective film having specular reflection, and reflects light to some extent. That is, it is not a metallic luster with a strong particle feeling like a metallic coating film, but a film having the luster of the metal itself or the metallic luster of the plating tone. Such a reflective film has a film thickness of, for example, 0.05 to 5 μm.

  The reflective film having specular reflection is, for example, a film whose 60 ° L * value is 150 or more. When the 60 degree L * value is less than 150, the specular reflection becomes weak and the flip-flop property of the obtained multilayer coating film becomes weak. Here, as shown in FIG. 1, the 60 ° L * value is obtained by irradiating the light source from an angle of 60 ° when the light receiving portion in a position perpendicular to the coating film to be measured is set to 0 °. Means the L * value of the received light. The L * value can be determined, for example, by measuring using a variable angle color difference meter (for example, “CM512m-3” manufactured by Minolta). The reflective film can be obtained, for example, by applying a metal particle-containing coating composition to a substrate.

(2.1. Metal particle-containing coating composition)
Specific examples of the metal particle-containing coating composition include those containing metal colloidal particles and / or vapor-deposited metal pigments and a resin component.

(2.1.1. Metal colloidal particles)
The metal colloidal particles preferably have a volume average particle diameter of 1 to 100 nm. If it is out of the above range, production problems may occur. The volume average particle diameter can be determined from the median D ₅₀ obtained were measured by dynamic light scattering method. An example of the measuring device is Microtrack 9340-UPA150 (manufactured by Nikkiso Co., Ltd.).

  The metal colloid particles are composed of metal fine particles and a protective layer. The metal species of the metal fine particle is not particularly limited, and examples thereof include gold, silver, copper, ruthenium, rhodium, palladium, osmium, iridium, platinum, and other metals such as indium, zinc, nickel, cobalt, and manganese. And alloys thereof. Of these, gold, silver, palladium, platinum, and alloys of these with other metals are preferable from the viewpoint of cost and ease of handling, and gold, silver, and these are preferable because they do not give a feeling of metal particles. More preferred is an alloy with nickel.

  Moreover, it does not specifically limit as a protective layer, For example, layers, such as a high molecular weight pigment dispersant by which the functional group with high affinity with respect to the pigment surface is introduce | transduced into the high molecular weight polymer, can be mentioned. As the high molecular weight pigment dispersant, commercially available ones can also be used. Examples of the commercially available products include Solsperse 27000, Solsperse 41090 (above, manufactured by Avicia), Dispersic 181, Dispersic 190, Dispersic 191, Dispersic 192 (above, manufactured by BYK Chemie), Polymer 450, Polymer 451, Polymer 452, Polymer 453, EFKA-1501, EFKA-1502, EFKA-4540, EFKA-4550 (above, manufactured by EFKA Chemical), Floren TG-720W, Floren-730W, Floren-740W, Floren-745W (above, Kyoeisha) Chemical Co., Ltd.), Ajisper PW911, Ajisper PB821 (above, Ajinomoto Co., Inc.), Jonkrill 678, Jonkrill 679, Jonkrill 62 (above, Johnson Polymer Co., Ltd.), etc. It can gel. These may be used alone or in combination of two or more.

  It does not specifically limit as another component, For example, a solvent etc. can be included. The solvent is not particularly limited, and water that can stably disperse the metal colloid particles in the system, or alcohols such as methanol, ethanol, and ethylene glycol, ketones such as acetone, and esters such as ethyl acetate. And a suitable organic solvent.

  The metal colloid particles can be obtained as a metal colloid particle solution stably dispersed in the solvent. The method for producing the metal colloid particle solution is not particularly limited. For example, a production process for obtaining a solution containing metal colloid particles by reducing a metal compound containing a desired metal species in the presence of a polymer dispersant, and The solution obtained in the above production step can be obtained by a method well known to those skilled in the art, such as through a concentration step in which ultrafiltration treatment is performed.

  The metal colloid particle solution metal thus obtained contains, for example, 83 to 99% by mass of a metal element in the solid content.

(2.1.2. Deposition metal pigment)
The vapor-deposited metal pigment is a flaky metal thin film, and is obtained by depositing a metal thin film on a plastic film, peeling the film, and forming the vapor-deposited metal thin film into a flake shape. The vapor-deposited metal pigment can be used in the form of flakes or dispersed in a solvent by a known method. The vapor deposition in the present invention means a dry plating method by vacuum vapor deposition, sputtering, ion plating, chemical vapor deposition (CVD method) or the like.

  The metal used for the vapor-deposited metal pigment includes the metals described above for the metal colloidal particles; metals such as aluminum, indium, titanium, nickel and tin; alloys such as aluminum titanium alloy, nickel alloy and chromium alloy; indium tin oxide And metal oxides such as titanium oxide. Preferably aluminum and / or aluminum titanium alloys are used.

The vapor-deposited metal pigment has, for example, an average thickness of 0.001 to 0.10 μm and an average particle diameter of 5 to 30 μm. The average particle size of the vapor-deposited metal pigment is the value of the median D ₅₀ of the particle size distribution measured by a laser diffraction particle size distribution measuring device.

(2.1.3. Resin component)
The metal particle-containing coating composition contains a resin component in addition to the metal colloid particles and / or the deposited metal pigment.

  The resin component is not particularly limited, and examples thereof include film-forming resins well known to those skilled in the art, such as acrylic resins, polyester resins, alkyd resins, epoxy resins, polyurethane resins, and polyether resins. Can be used alone or in combination of two or more.

  The resin component may contain a curing agent, and examples of the curing agent include amino resins, (block) polyisocyanate compounds, amines, polyamides, imidazoles, imidazolines, and polycarboxylic acids. Can do. The curing agent is preferably at least one of an amino resin and a (block) polyisocyanate compound.

  When the said resin component contains a hardening | curing agent, as a ratio of a film-forming resin and a hardening | curing agent, 90-50 mass% of film-forming resins and 10-50 mass of hardening | curing agents are conversion of solid content. Preferably, the film-forming resin is 85 to 60% by mass, and the curing agent is 15 to 40% by mass. When the curing agent is less than 10% by mass (when the coating film-forming resin exceeds 90% by mass), curing in the coating film is not sufficient. On the other hand, when the curing agent exceeds 50% by mass (when the coating film-forming resin is less than 50% by mass), the storage stability of the paint is lowered and the curing rate is increased, so that the coating film appearance is deteriorated.

(2.1.4. Each formulation in the coating composition containing metal particles)
The content of the resin component in the metal particle-containing coating composition is not particularly limited. For example, the solid content of the resin component with respect to the solid content of the metal particle-containing coating composition is 0/100 to 50/100 in mass. Ratio (solid content of resin component / solid content of metal particle-containing coating composition), more preferably 5/100 to 40/100.

  Content of the metal colloid particle in a metal particle containing coating composition is 50-100 mass% with respect to solid content of a metal particle containing coating composition, Preferably it is 60-98 mass%.

  The content of the vapor deposition metal pigment in the metal particle-containing coating composition is preferably 0.5 to 80% by mass with respect to the solid content of the metal particle-containing coating composition.

  In addition, it is preferable to use the said metal colloid particle and the said vapor deposition metal pigment together from a viewpoint of suppressing the nonuniformity of the reflecting film obtained and stabilizing 60 degree L * value high. In this case, the metal colloid particles: the deposited metal particles are preferably in a mass ratio of 100: 0.5 to 100: 50. If it is out of the above range, unevenness suppression may be insufficient or a metallic particle feeling may occur.

  The metal particle-containing coating composition may contain other components in addition to the metal colloid particles and / or vapor deposition metal pigment, the resin component, and the component. Other components include UV absorbers, light stabilizers, polyethylene wax, anti-settling agents, curing catalysts, antioxidants, leveling agents, surface conditioners such as silicone and organic polymers, viscosity control agents, anti-sagging agents, A thickener, an antifoamer, a lubricant, a crosslinked polymer particle (microgel), etc. can be mentioned.

  The metal particle-containing coating composition can take various forms such as a solvent type, an aqueous type and a powder type. As the solvent-based paint or water-based paint, a one-component paint may be used, or a two-component paint such as a two-component urethane resin paint may be used.

  The metal particle-containing coating composition can be obtained by a method known to those skilled in the art, for example, by mixing and dispersing the above components.

(2.2. Application method)
The method for applying the metal particle-containing coating composition is not particularly limited. For example, application by brush or roller, spray coating, rotary atomizing coating and electrostatic coating, spin coating, silk screen, ink jet, etc. Can be mentioned. It can be appropriately selected according to the shape of the object to be coated and the smoothness and reflection characteristics of the resulting reflection film. Moreover, as a film thickness, it is preferable that it is more than the film thickness which can completely hide the base | substrate (base material) of the said metal particle containing coating composition, for example, it apply | coats so that it may become 0.05-5 micrometers as a dry film thickness To do. From the viewpoint of suppressing hue unevenness, it is more preferably 0.1 to 4.5 μm.

(3. Colored pigment-containing coating film)
The multilayer coating film of the present invention has a color pigment-containing coating film on the reflective film having specular reflection. The colored pigment-containing coating film does not completely hide the background like a so-called solid color, but develops color while transmitting incident light, and the reflected light reflected by the lower reflective film. The color is developed while further transmitting.

  The film thickness necessary for the base concealment of the colored pigment-containing coating film used in the present invention is 12 to 100 μm, and the film thickness as the color pigment-containing coating film is 60% to 100% of the film thickness necessary for the base concealment. %. If the film thickness necessary for concealing the base is less than 12 μm, the film thickness for obtaining a design becomes too thin and it becomes difficult to adjust the film thickness, and a smooth and uniform colored pigment-containing coating film cannot be obtained. When it exceeds, the film thickness which can obtain a design will become too thick, and the workability | operativity at the time of application | coating will fall. It does not specifically limit as a film thickness of the said color pigment containing coating film, Although it can set suitably according to a desired design, For example, it is 7.2-60 micrometers, More preferably, it is 8-30 micrometers.

  The colored pigment-containing coating film can be obtained, for example, by applying a colored pigment-containing coating composition on the reflective film.

(3.1. Coloring pigment-containing coating composition)
Specific examples of the color pigment-containing coating composition include those containing a color pigment and a resin component.

  Examples of the color pigment include various organic and inorganic color pigments and extender pigments. Examples of the color pigment include organic azo lake pigments, insoluble azo pigments, condensed azo pigments, diketopyrrolopyrrole pigments, benzimidazolone pigments, phthalocyanine pigments, indigo pigments, perinone pigments, and perylene pigments. Pigments, dioxazine pigments, quinacridone pigments, selenium pigments, isoindoline pigments, isoindolinone pigments, metal complex pigments, inorganic yellow lead, zinc white, yellow iron oxide, bengara, carbon black, cadmium red , Molybdenum red, chrome yellow, chromium oxide, Prussian blue, cobalt blue, titanium oxide (for example, titanium dioxide) and the like, and extender pigments include calcium carbonate, barium sulfate, clay, aluminum powder, talc and the like It is done. Moreover, the color pigment containing coating film of a desired hue can be formed by using the said color pigment 1 type or in combination of 2 or more types.

  It does not specifically limit as a resin component, What was described in the said metal particle containing coating composition can be mentioned.

  The color pigment content (PWC) of the color pigment-containing coating composition is 0.01 to 18% by mass. PWC (mass%) is calculated by (total mass of all pigments) / (total mass of solids of all pigments and all resin components) × 100.

  When the content of the color pigment in the color pigment-containing coating composition is less than 0.01% by mass, the underlying concealability is too low, and it is necessary to increase the film thickness in order to obtain a desired design. If the amount exceeds 18% by mass, the smoothness of the resulting coating film may be reduced.

  The colored pigment-containing coating composition can contain other components in addition to the colored pigment and the resin component. Other components are not particularly limited, and specific examples include those described in the above-mentioned metal particle-containing coating composition.

  Similarly, the form of the color pigment-containing coating composition is not particularly limited, and specific examples include those described in the above-mentioned metal particle-containing coating composition.

  The color pigment-containing coating composition can be obtained by a method known to those skilled in the art, for example, kneading and dispersing the above components using a mill, kneader, roll, or the like.

  The film thickness necessary for concealing the base of the color pigment-containing coating composition can be measured using a concealment rate measuring paper (standard: JIS K5600) used for measuring the concealing power of the coating composition. The method for measuring the hidden film thickness is as follows. Spray coating is performed on a 2 × 2 cm square black and white checkered pattern of the concealment rate measurement paper so that a dry film thickness gradient of 20 to 300 μm is formed, and then baking is performed to cure. Next, visually, the limit coating film part where the black and white checkered pattern cannot be seen through is judged, the film thickness of the part is measured, and this film thickness is determined as the film thickness necessary for the base concealment (black and white concealment film thickness). decide.

(3.2. Application method)
The method for applying the color pigment-containing coating composition is not particularly limited, and is 60% to less than 100% of the film thickness necessary for covering the base, 7.2 to 60 μm as the dry film thickness, and more preferably 8 to 30 μm. Except for the coating, there may be mentioned those described in the above-mentioned metal particle-containing coating composition.

  In the present invention, by setting the film thickness (dry film thickness) of the coating film formed from the color pigment-containing coating composition to less than 60% to 100% of the film thickness necessary for concealing the base, light transparency is secured to some extent. can do. Therefore, although the formed multilayer coating is a solid color, depending on the viewing angle, the metallic luster of the lower reflective film appears on the surface, and a mysterious metal that could not be obtained with a coating containing a conventional glittering material. A glossy appearance is obtained. Further, by changing the light transmittance by further adjusting the film thickness of the color pigment-containing coating film, it is possible to change the degree that the metallic luster appearance can be visually recognized on the surface.

(4. Clear coating film)
The multilayer coating film of the present invention may further include a clear coating film. The clear coating film is provided to protect the underlying color pigment-containing coating film or to provide other functions. It does not specifically limit as a film thickness of the said clear coating film, For example, it is 30-60 micrometers. The clear coating film can be obtained, for example, by applying a clear coating composition on the colored pigment-containing coating film.

(4.1. Clear coating composition)
Specific examples of the clear coating composition include those containing a resin component. It does not specifically limit as a resin component, Specifically, what was described in the place of the said metal particle containing coating composition can be mentioned.

  The clear coating composition can contain other components in addition to the resin component. The other components are not particularly limited, and specific examples include those described for the metal particle-containing coating composition.

  The clear coating composition may be a so-called color clear coating composition containing a color pigment, but the transparency of the resulting clear coating must be ensured, so that the film thickness necessary for concealing the underlayer is required. Needs to exceed 100 μm.

  The coating form of the clear coating composition is not particularly limited, and may be any of an organic solvent type, an aqueous type (for example, water solubility, water dispersibility, emulsion), a non-aqueous dispersion type, and a powder type.

(4.2. Application method)
The method for applying the clear coating composition is not particularly limited, and specifically, those described in the above-mentioned coating composition containing metal particles, except that coating is performed so that the dry film thickness is 30 to 60 μm. be able to.

  The clear coating composition is preferably formed in a so-called wet-on-wet coating method in which a colored pigment-containing coating composition is applied and then applied in an uncured state. In order to prevent this, a viscosity inhibitor known to those skilled in the art can be contained. Content of a viscosity control agent is 0.1-10 mass parts with respect to 100 mass parts of resin solid content of a clear coating composition, Preferably it is 0.2-8 mass parts, More preferably, it is 0.5-6. Added in parts by weight. When the amount exceeds 10 parts by mass, the appearance is deteriorated. When the amount is less than 0.1 parts by mass, the viscosity control effect cannot be obtained, which causes problems such as sagging.

  The method for producing the clear coating composition is not particularly limited, and methods known to those skilled in the art can be used.

  The multi-layer coating film of the present invention has a 15 degree L * value of 50 or more and a 75 degree L * value of 30 or less. When deviating from the above range, the effect of the present invention cannot be obtained. Preferably, the 15 degree L * value is 55 or more, and the 75 degree L * value is 20 or less. Here, as shown in FIG. 1, the 15 degree L * value is obtained by irradiating the light source from an angle of 15 degrees when the light receiving portion in the vertical position with respect to the coating film to be measured is set to 0 degree. Means the L * value of the received light. Similarly, the L * value of 75 degrees is the L * of the light received by irradiating the light source from an angle of 75 degrees when the light receiving portion in a position perpendicular to the coating film to be measured is set to 0 degrees. Mean value. The L * value can be determined, for example, by measuring using a variable angle color difference meter (for example, “CM512m-3” manufactured by Minolta).

  The 15-degree L * value and the 75-degree L * value of the multilayer coating film in the present invention can be determined by the reflection film and the color pigment-containing coating film described above. L * values are closely related to each other. The L * value of the reflective film can be controlled by adjusting the metal species, particle diameter, content, etc. contained in the reflective film. Similarly, the L * value of the colored pigment-containing coating film can be controlled by adjusting the pigment type, particle diameter, content, and the like.

  Further, the flip-flop value of the multilayer coating film can be obtained from 15 ° L * value / 75 ° L * value. The flip-flop value is an index that can indicate numerically the difference in hue and brightness when the coating film is viewed from the highlight direction and when viewed from the shade direction. Is large, indicating that the color is clearly visible, and that the flip-flop property is high. Here, the flip-flop property refers to the property that the hue and brightness of the coating film change depending on the incident angle of the light source and the direction of the light receiving unit, that is, the performance in which the hue and brightness change depending on the viewing angle. For example, by forming a coating film having a high flip-flop property on an object to be coated such as an automobile body, the body shape of the object to be coated can be more emphasized.

  In the present invention, the flip-flop value is 2 or more, preferably 2.5 or more. If the flip-flop value is less than 2, a design having a strong flip-flop property which is an effect of the present invention cannot be obtained.

Multi-layer coating film forming method The multi-layer coating film forming method of the present invention comprises a step (1) of applying a metal particle-containing coating composition on a substrate to form a reflective film having specular reflection, the step (1) The step (2) of forming a color pigment-containing coating film by coating the color pigment-containing coating composition on the reflective film obtained in (1) is characterized in that it comprises.

  The first step of the method for forming a multilayer coating film of the present invention is a step (1) of applying a metal particle-containing coating composition to a substrate to form a reflective film having specular reflection. Examples of the metal particle-containing coating composition and coating method include those described in the metal particle-containing coating composition.

  The second step of the method for forming a multilayer coating film of the present invention is a step of forming a color pigment-containing coating film by applying a color pigment-containing coating composition on the reflective film obtained in the above step (1) (2 ). Examples of the color pigment-containing coating composition and coating method include those described in the above-mentioned color pigment-containing coating composition.

  After the step (2) is completed, a multilayer coating film can be obtained through the heat curing step.

  Moreover, the multilayer coating film formation method of this invention forms a clear coating film by apply | coating a clear coating composition on the color pigment containing coating film obtained at the said process (2) as a 3rd process. Step (3) may be included.

Heat curing step The multilayer coating film forming method of the present invention may be provided with a heat curing step after each of steps (1) and (2) and, if necessary, step (3).

  The heat curing step can be performed using a conventional heat curing furnace (for example, a gas furnace, an electric furnace, an IR furnace, an induction heating furnace, or the like). The heat curing temperature can be appropriately set according to the resin component contained in each of the metal particle-containing coating composition, the color pigment-containing coating composition and the clear coating composition, for example, 120 to 160 ° C., The heat curing time is, for example, 10 to 30 minutes.

  In the present invention, after step (1), step (2) is performed wet-on-wet, and then a heat curing step is performed to form a multilayer coating film (2-coat 1-bake (2C1B)), step ( In the case where 3) is also performed, after step (1), step (2) and step (3) are each performed wet on wet, and then a heat curing step is performed to form a multilayer coating film (3 Coat 1 bake (3C1B)) is preferable from the viewpoint of cost, simplicity, and environmental load.

  Before the heat curing step, after step (1) or when step (3) is also performed, after step (1) and (2), an operation called a time interval is performed. In this interval, the solvent contained in the coating film can be sufficiently volatilized, and the appearance of the multilayer coating film is improved. The interval is, for example, 10 seconds to 15 minutes.

  Moreover, you may perform drying operation called preheating within the time of an interval, and volatilization of the solvent contained in a coating film can be performed efficiently in a short time by this preheating. This drying operation does not actively cure the coating film. Therefore, as said drying conditions, it is 5 to 10 minutes at room temperature-100 degreeC, for example. Preheating can be performed using, for example, a warm air heater or an infrared heater.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to a following example. In the examples, “parts” means “parts by mass” unless otherwise specified.

Production Example 1 Preparation of Solution Containing Silver Colloidal Particles In a 2 liter Kolben, 12 g of Disperbic 190 (pigment dispersant manufactured by Big Chemie) and 420.5 g of ion-exchanged water were added. This Kolben was placed in a water bath and stirred at 50 ° C. until Dispersic 190 was dissolved. To this, 100 g of silver nitrate dissolved in 420.5 g of ion-exchanged water was added with stirring, and the mixture was stirred at 70 ° C. for 10 minutes. Next, when 262 g of dimethylaminoethanol was added, the liquid turned black instantly and the liquid temperature rose to 76 ° C. When the liquid temperature dropped to 70 ° C. as it was, stirring was continued for 2 hours while maintaining this temperature to obtain an aqueous solution of silver colloid exhibiting a dark yellow color. The obtained reaction solution was transferred to a 1 liter plastic bottle and allowed to stand in a thermostatic chamber at 60 ° C. for 18 hours. Next, AHP1010 (Asahi Kasei Corporation ultrafiltration module, molecular weight cut off 50000, number of membranes used 400), magnet pump, 3 liter stainless steel cup with tube connection port at the bottom are connected by silicon tube, ultrafiltration The device. The reaction solution that had been allowed to stand for 18 hours in a constant temperature room at 60 ° C. was placed in a stainless steel cup, 2 liters of ion-exchanged water was further added, and the pump was operated to perform ultrafiltration. After about 40 minutes, when the filtrate from the module became 2 liters, 2 liters of ethanol was added to the stainless steel cup. Thereafter, the filtrate was confirmed to have a conductivity of 300 μS / cm or less, and concentrated until the amount of the mother liquor was 500 ml. Subsequently, an ultrafiltration device comprising a 500 ml stainless steel cup containing mother liquor, AHP0013 (Asahi Kasei Corporation ultrafiltration module; molecular weight cut off 50000, number of membranes used 100), a tube pump, and an aspirator was assembled. The mother liquor obtained previously was put into this stainless steel cup and concentrated to increase the solid content concentration. When the mother liquor reached about 100 ml, the pump was stopped to complete the concentration, and a solution containing silver colloid particles having a solid content of 30% was obtained. The volume average particle diameter of the silver colloid particles in this solution was 27 nm from the value of the median D ₅₀ obtained by measurement with Microtrac 9340-UPA150 (manufactured by Nikkiso Co., Ltd.). Moreover, it was 96 mass% when content rate of the metal (silver) in solid content was measured using TG-DTA (Seiko Instruments differential thermal analyzer).

Production Example 2 Preparation of a solution containing colloidal gold particles 13.8 g of Dispersic 191 (Pig Dispersant manufactured by Big Chemie) instead of Dispersic 190 and 1350 g of 5% by mass of chloroauric acid ethanol solution instead of 100 g of silver nitrate Except for the above, a solution of colloidal gold particles having a solid content of 20% was obtained in the same manner as in Production Example 1. From the median D ₅₀ value obtained by carrying out the same measurement as in Production Example 1, the (volume) average particle diameter of the gold colloid particles in this solution was 18 nm. The gold content in the solid content was 90% by mass.

Production Example 3 Preparation of Metal Particle-Containing Coating Composition A Acrylic resin (styrene / methyl methacrylate / ethyl methacrylate / hydroxyethyl methacrylate / methacrylic acid copolymer, number average molecular weight of about 20000, hydroxyl value 45 mgKOH / g, acid value 15 mgKOH / g, solid content 50% by mass) and Uban 20SE (Mitsui Chemical Co., Ltd. melamine resin, solid content 60% by mass) in a solid content mass ratio of 80:20 to 15 parts of the resin mixture solid content The solution containing the silver colloid particles obtained in Production Example 1 was blended so as to have a solid content of 100 parts. Next, the mixture was stirred and mixed with an organic solvent (toluene / xylene / ethyl acetate / butyl acetate mass ratio = 70/15/10/5) with a stirrer so as to obtain an appropriate coating viscosity, thereby preparing a coating composition A containing metal particles. .

Production Example 4 Preparation of Metal Particle-Containing Coating Composition B As in Production Example 3, except that the solution containing colloidal gold particles obtained in Production Example 2 was used in place of the solution containing silver colloidal particles in Production Example 1. Thus, a metal particle-containing coating composition B was prepared.

Production Example 5 Preparation of Metal Particle-Containing Coating Composition C In Production Example 3, METALURE L-55700 (evaporated metal pigment manufactured by ECKART WERKE) is added to 5.0 parts of solid content with respect to 15 parts of resin mixture solid content. In addition to the above, the mixture was mixed and stirred to prepare a coating composition C containing metal particles.

Production Example 6 Preparation of Metal Particle-Containing Coating Composition D In Production Example 4, the solid content of METALURE L-55700 (deposited metal pigment manufactured by ECKART WERKE) is further 5.0 parts with respect to 15 parts of the resin mixture solids. In addition to the above, the mixture was stirred and a metal particle-containing coating composition D was prepared.

Production Example 7 Preparation of Red Colored Pigment-Containing Coating Composition 1 236 parts of Nippon Paint's acrylic emulsion (average particle size 150 nm, nonvolatile content 20%, solid content acid value 20 mgKOH / g, hydroxyl value 40 mgKOH / g), Nippon Paint 28.3 parts of water-soluble acrylic resin (non-volatile content 30.0%, solid content acid value 40 mgKOH / g, hydroxyl value 50 mgKOH / g), Primepole PX-1000 (Bifunctional polyether polyol manufactured by Sanyo Chemical Industries) 8.6 parts of a number average molecular weight 400, hydroxyl value 278 mg KOH / g, primary / secondary hydroxyl value ratio = 63/37, non-volatile content 100%, and Cymel 204 (mixed alkylated melamine resin manufactured by Mitsui Cytec Co., Ltd.) The resin component obtained by mixing and stirring 21.5 parts of non-volatile content (100% nonvolatile content) A red colored pigment-containing coating composition 1 was prepared by blending, mixing and dispersing DO BO (organic red pigment manufactured by Ciba Specialty Chemicals Co., Ltd.) so that the pigment mass concentration (PWC) was 10 mass%. The film thickness required for the base concealment was measured by a black and white concealment test according to JIS K 5600 and found to be 25 μm.

Production Example 8 Preparation of Red Colored Pigment-Containing Coating Composition 2 A red colored pigment-containing coating composition 2 was prepared in the same manner as in Production Example 7 except that the organic red pigment was blended so that the PWC was 8% by mass. . Furthermore, when the film thickness required for base concealment was measured in the same manner as in Production Example 7, it was 45 μm.

Production Example 9 Preparation of Green Colored Pigment-Containing Coating Composition 1 With respect to the resin component used in Production Example 7, Lionol Green 6YKP-N (Organic Green Pigment manufactured by Toyo Ink Co., Ltd.) has a pigment mass concentration (PWC) of 10 A green color pigment-containing coating composition 1 was prepared by blending, mixing and dispersing so as to be in mass%. Furthermore, when the film thickness required for base concealment was measured in the same manner as in Production Example 7, it was 25 μm.

Production Example 10 Preparation of Green Colored Pigment-Containing Coating Composition 2 A green color pigment-containing coating composition 2 was prepared in the same manner as in Production Example 9 except that the organic green pigment was blended so that the PWC was 8% by mass. . Furthermore, when the film thickness required for base concealment was measured in the same manner as in Production Example 7, it was 40 μm.

Example 1
A power-top U-50 (cationic electrodeposition paint manufactured by Nippon Paint Co., Ltd.) is electrodeposited onto a chemically treated dull steel plate (300 mm in length, 100 mm in width and 0.8 mm in thickness) to a dry film thickness of 25 μm. Baked at 160 ° C. for 30 minutes to form an electrodeposition coating film.
On the obtained electrodeposition coating film, Olga TO-65 Gray (Nippon Paint Co., Ltd., Nippon Paint Co., Ltd.) was spray-coated so that the dry film thickness was 35 μm, and baked at 140 ° C. for 30 minutes. Formed.
On the obtained intermediate coating film, the metal particle-containing coating composition A obtained in Production Example 3 is spray-coated to a dry film thickness of 3 μm to form a reflective film, and preheated at 100 ° C. for 10 minutes. did. The 60-degree L * value of this reflective film was 250 as measured with a goniochromimeter (trade name: “CM512m-3”, manufactured by Minolta).
Next, on the reflective film, the red color pigment-containing coating composition 1 obtained in Production Example 7 was spray-coated so that the dry film thickness was 17 μm to form a red color pigment-containing coating film.
Further, on the obtained red color pigment-containing coating film, MacFlow O-1600-1 (Organic solvent type clear paint manufactured by Nippon Paint Co., Ltd.) was spray-coated so that the dry film thickness was 35 μm, and the clear coating film was formed. After the formation, baking was performed at 140 ° C. for 30 minutes, and the reflective film, the red color pigment-containing coating film and the clear coating film were cured to obtain a multilayer coating film.
When the obtained multilayer coating film was measured for 15 ° L * value and 75 ° L * value with CM512m-3, it was 15 ° L * value = 59.4 and 75 ° L * value = 14.7. It was.

Examples 2-4
Instead of the metal particle-containing coating composition A obtained in Production Example 3, it was the same as Example 1 except that the metal particle-containing coating compositions B to D obtained in Production Examples 4 to 6 were used, respectively. Thus, a multilayer coating film was obtained (Examples 2 to 4).
The obtained multilayer coating film was measured for the 15 ° L * value and the 75 ° L * value in the same manner as in Example 1. The measured values are shown in Table 1.

Examples 5-7
Instead of the red colored pigment-containing coating composition 1 obtained in Production Example 7, the red colored pigment-containing coating composition 2 and the green colored pigment-containing coating composition 1 and 2 obtained in Production Examples 8 to 10, respectively. Except having used, it carried out similarly to Example 1, and obtained the multilayer coating film (Examples 5-7).
The obtained multilayer coating film was measured for the 15 ° L * value and the 75 ° L * value in the same manner as in Example 1. The measured values are shown in Table 1.

Comparative Example 1
A multilayer coating film was obtained in the same manner as in Example 1 except that the red color pigment-containing coating composition 1 obtained in Production Example 7 was applied so that the dry film thickness was 30 μm.
The obtained multilayer coating film was measured for the 15 ° L * value and the 75 ° L * value in the same manner as in Example 1. The measured values are shown in Table 1.

Production Example 11 Preparation of Luminous Pigment-Containing Coating Composition To the resin component used in Production Example 7, Alpaste 91-0562 (aluminum flake pigment manufactured by Toyo Aluminum Co., Ltd.) was blended so that the PWC was 10% by mass. A glittering pigment-containing coating composition was prepared in the same manner as in Production Example 7 except that. Furthermore, when the film thickness required for base concealment was measured in the same manner as in Production Example 7, it was 25 μm.

Comparative Example 2
Implemented except that the glittering pigment-containing coating composition obtained in Production Example 11 was used in place of the metal particle-containing coating composition A obtained in Production Example 3, and the coating was applied to a dry film thickness of 17 μm. A bright pigment-containing coating film was obtained in the same manner as in Example 1. The 60 degree L * value of this coating film was measured in the same manner as in Example 1. The results are shown in Table 1.

  Further, in the same manner as in Example 1, a red colored pigment-containing coating film and a clear coating film were formed, and then heated and cured at 140 ° C. for 30 minutes to obtain a glittering pigment-containing coating film, a red coloring pigment-containing coating film, and a clear coating film. The coating film was cured to obtain a multilayer coating film.

  The obtained multilayer coating film was measured for the 15 ° L * value and the 75 ° L * value in the same manner as in Example 1. The measured values are shown in Table 1.

The flip-flop property (difference in color when viewed from the front side and the color when viewed obliquely) of the multilayer coating films obtained from Evaluation Examples 1 to 7 and Comparative Examples 1 and 2 and the metallic particle feeling are visually observed. The evaluation results are shown in Table 1. The evaluation criteria were as follows.

(1) Flip-flop property ○: When the multi-layer coating film is viewed from the front, a bright metallic luster appearance in which the brightness of the metallic luster by the reflective film and the hue of the color pigment-containing coating film are mixed is felt diagonally When I looked at the paint film, it was not bright and had a solid color hue.
Δ: No brightness when viewed from the front or oblique side, and a metallic particle feeling when viewed from the front, and a solid color tone when viewed from the side Met.
X: When the multilayer coating film was viewed from the front and from the side, there was no change in brightness and hue, and both were solid color hues.

(2) Metal particle feeling ○: Metal particle feeling is not visible.
Δ: A feeling of metal particles can be seen a little.
X: A metallic particle feeling is visible.

  A multilayer coating film comprising a reflective film having a specular reflection and a colored pigment-containing coating film in order, having a 15-degree L * value of 50 or more and a 75-degree L * value of 30 or less according to the present invention, When viewed from the side, the hue is bright and metallic, and when viewed from the side, the hue is a solid color tone and has flip-flop properties (Examples 1 to 7). In the case of completely hiding the reflective film (Comparative Example 1), or in the case of a glittering pigment-containing coating film (Comparative Example 2), the metallic film feeling remains in the reflective film, resulting in insufficient flip-flop properties. The effect of could not be obtained.

  By the multilayer coating film forming method of the present invention, a solid color coating film having flip-flop properties can be provided, and a finished appearance different from a coating film containing a conventional glittering material can be obtained. In addition, by changing the light transmittance of the solid color coating film on the reflective film with specular reflection, the degree to which the metallic luster appearance is visible on the surface changes, and the metallic luster appearance is always exposed to the front. It is possible to selectively provide a coating film appearance that is different from the glittering material-containing coating film.

FIG. 1 is a diagram schematically illustrating a method for measuring an L * value and a flip-flop value.

Claims (7)

  A multilayer coating film comprising a reflective film having a specular reflection and a colored pigment-containing coating film on a substrate, the 15-degree L * value of the multilayer coating film being 50 or more, and 75-degree L * Multilayer coating film characterized by having a value of 30 or less.   The multilayer coating film according to claim 1, wherein the flip-flop value is 2 or more.   The multilayer coating film of Claim 1 or 2 provided with a clear coating film on the said color pigment containing coating film. Step (1) of applying a metal particle-containing coating composition on a substrate to form a reflective film having specular reflection, and applying a coloring pigment-containing coating composition on the reflective film obtained in the step (1) A method for forming a multilayer coating film comprising the step (2) of forming a colored pigment-containing coating film,
The film thickness required for concealing the base of the color pigment-containing coating film is 12 to 100 μm,
The film thickness of the color pigment-containing coating film obtained in the step (2) is 60% to less than 100% of the film thickness necessary for the base concealment, and
A multilayer coating film forming method, wherein the obtained multilayer coating film has a 15 degree L * value of 50 or more and a 75 degree L * value of 30 or less.   The method for forming a multilayer coating film according to claim 4, wherein the flip-flop value is 2 or more.   The method for forming a multilayer coating film according to claim 4 or 5, wherein a content of the color pigment contained in the color pigment-containing coating composition is 0.01 to 18% by mass.   Furthermore, the process (3) of apply | coating a clear coating composition on the coloring pigment containing coating film obtained at the said process (2), and forming a clear coating film is included. A method for forming a multilayer coating film according to 1.

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