JP6796982B2 - Evaluation method of metallic design - Google Patents

Description

The present invention relates to a method for evaluating a metallic design.

Metallic paints containing various bright pigments (aluminum flakes, mica flakes, graphite, etc.) are widely used. The appearance of the color of the coating film obtained by applying the metallic paint (hereinafter referred to as "metallic color") changes depending on the observation angle. On the other hand, a paint color in which the appearance of the color does not change depending on the observation angle is called a "solid color".

In Patent Document 1, as a method for measuring the metallic feeling of a metallic coating film, the color of reflected light is measured at a plurality of light receiving angles in a plurality of metallic coating films, and the obtained set of L ^* luminance is regarded as a variable. A method of performing principal component analysis and expressing the brightness parameter and the whiteness parameter by the linear combination formula of L ^* brightness is described.

Japanese Unexamined Patent Publication No. 2004-286672

In metallic coatings such as silver metallic and super metallic, highlights (observation angles with a small angle from specular light, for example, a light receiving angle of 15 °) have high brightness, and shades (observation angles with a large angle from specular light). For example, since the discoloration property (flip flop) is large so that the light intensity becomes low at a light receiving angle of 75 °), it is difficult to obtain a parameter that matches the visual evaluation.

In the method described in Patent Document 1, each coefficient of the linear combination formula is derived by associating and analyzing the visual evaluation result and the L ^* brightness having different light receiving angles. Since the main component parameters obtained by Patent Document 1 are obtained depending on the visual evaluation result, it is not possible to express the metallic feeling by simple parameters independent of the visual evaluation result.
Further, according to the study by the present inventors, it is difficult to accurately evaluate the supermetal-like coating color in which the brightness of the highlight is high and the brightness is greatly reduced even if the observation angle is slightly changed, using the conventional parameters. It turned out to be.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for evaluating a metallic design capable of quantifying a metallic feeling with simple parameters.

In order to solve the above-mentioned problems, the present invention calculates the ratio of the specular gloss of a design surface having a metallic design to the brightness of the design surface at an angle away from the regular reflection direction, and obtains the metallic design by the ratio. Provided is an evaluation method of a metallic design characterized by evaluation.

Further, the mirror glossiness may be measured with an incident angle of 60 ° ± 5 °.
Further, the brightness may be measured with an incident angle of 45 ° ± 5 ° and an angle of 45 ° ± 5 ° from the specular reflection direction toward the incident direction as the light receiving angle.

Also, the brightness, the brightness _Y in the XYZ color system, _{X 10 Y} 10 _Z lightness _Y 10 in ₁₀ color ^system, L ^* a * ^{b *} color system or ^L * ^u * ^{v *} lightness L in the color system ^It may be any of ^* .
Further, the lightness is preferably the lightness Y in the XYZ color system.
Further, the design surface may have a metallic coating film or a metal layer.

According to the present invention, the metallic feeling is quantified by a simple parameter by combining the specular gloss, which is a color measurement parameter in the vicinity of the regular reflected light, and the brightness at an angle away from the regular reflected light, and the visual evaluation result. You can get an order close to.

It is explanatory drawing of (a) mirror glossiness and (b) the measurement angle of brightness.

Hereinafter, the present invention will be described based on a preferred embodiment. FIG. 1 (a) shows an explanatory diagram of a measurement angle of mirror gloss, and FIG. 1 (b) shows an explanatory diagram of a measurement angle of brightness.

The method for evaluating the metallic design of the present embodiment is a step of measuring the mirror glossiness of the design surface 10 having the metallic design and a step of measuring the brightness of the design surface 10 in the light receiving direction 14 at an angle away from the regular reflection direction 12. And, it has a step of calculating the ratio of mirror glossiness: lightness, and the metallic design can be evaluated by the value of this ratio.

(Measurement of mirror gloss)
Examples of the method for measuring the mirror glossiness include JIS Z 8741 (mirror glossiness-measurement method). In this method, with the design surface 10 as the sample surface, light is incident on the design surface 10 from a predetermined incident direction 11, and the luminous flux in the regular reflection direction 12 due to specular reflection is measured.
The incident angle θ ₁ is an angle formed by the incident direction 11 and the normal direction 13. The specular reflection angle θ ₂ , which is the angle formed by the specular reflection direction 12 and the normal direction 13, is equal to the incident angle θ ₁ .

The glass surface having a refractive index of 1.567, which is a constant value over the entire visible wavelength range, is used as the standard surface, and the specular luminous flux from the standard surface with respect to the incident angle θ ₁ is φ _0S . When the specular reflection light flux from the sample surface with respect to the incident angle theta ₁ (design surface) was phi _S, specular gloss G _{S (theta 1)} is obtained by the following expression.

G _S (θ ₁ ) = (φ _S / φ _{0 S} ) × G _OS (θ ₁ )

Here, G _OS (θ ₁ ) is the mirror glossiness of the standard surface, and if the refractive index of the standard surface is 1.567, G _OS (θ ₁ ) = 100% regardless of the incident angle θ _1. Is. Therefore, it is possible to determine the specular glossiness G _{S (θ 1)} by the following equation. The unit (%) of the mirror glossiness can be omitted.

G _S (θ ₁ ) = (φ _S / φ _{0 S} ) × 100 (%)

The incident angle θ ₁ can be selected from, for example, 20 °, 45 °, 60 °, 75 °, 85 °, etc., depending on the degree of reflection on the design surface. The mirror glossiness at an incident angle of 60 ° (60 degree mirror glossiness) can be used as standard, but the incident angle may be determined within the range of 60 ° ± 5 ° (55 to 65 °). Examples of the tolerance of the set angle include 0.1 ° and 0.2 °.

The specular gloss measuring device has a light source (not shown) in the incident direction 11 and a receiver (not shown) in the specular reflection direction 12. By injecting a parallel light flux from the light source onto the design surface, the parallel light flux reflected from the design surface can be measured by the receiver. An optical system including a lens, an aperture, and the like may be provided between the light source and the light receiver and the design surface. The opening angle of the luminous flux can be regulated by the size of the aperture.

(Measurement of brightness)
The brightness may be a parameter that can quantify the amount of reflection (brightness) relative to the color of the silver-based, for example, brightness _{Y, X 10 Y 10 Z 10} Table brightness _{Y 10} in the color system in the XYZ color system, L ^* a ^* b ^* color system or L ^* u ^* v ^* lightness L ^* in the color system can be mentioned (see, for example, former JIS Z 8701, former JIS Z 8729, JIS Z 8781, etc.).
There is generally a relationship of L ^* = 116 (Y / 100) ¹ /3-16 between lightness Y and lightness L ^* , but L ^* a ^* b ^* color system or L ^* u ^* v ^* table. Since the color system is a color system defined with the intention of a uniform color space and is greatly influenced by the psychological amount, it is preferable to adopt the lightness Y rather than the lightness L ^* .

The light source may be circular illumination in which the light source is provided in a circumferential shape that gives the same incident angle θ ₁ in the normal direction 13, and unidirectional illumination in which the light source is provided only at one point on the circumference of the incident angle θ _1. Alternatively, it may be an annular illumination in which light sources are provided at a large number of points on the circumference of the incident angle θ ₁ .
In the case of unidirectional illumination, the normal reflection direction 12 and the light receiving direction 14 are in the surface (incident surface) including the incident direction 11 and the normal direction 13, and the light receiving angle θ ₃ is the normal reflection direction 12 and the light receiving direction 14. It is calculated as the angle formed by. At this time, the sign of the light receiving angle θ ₃ is positive in the rotation angle in the direction from the normal reflection direction 12 to the incident direction 11 (clockwise in FIG. 1 (a)), and the direction away from the incident direction 11 (FIG. 1 (a)). The sign of the light receiving angle θ ₃ is negative at the rotation angle (counterclockwise). When the light receiving angle θ ₃ is a positive value, the positive sign (+) may be omitted. When the light receiving direction 14 coincides with the normal direction 13 (the light receiving angle θ ₃ is equal to the specular reflection angle θ ₂ ), even if the incident direction 11 deviates around the normal direction 13, the deviation of the light receiving direction 14 can be suppressed. preferable.

The light receiving direction 14 can be selected from, for example, 15 °, 25 °, 45 °, 60 °, 75 °, 110 °, etc., with the angle with respect to the specular reflection direction 12 as the light receiving angle θ ₃ . A small light receiving angle θ ₃ such as 10 °, 15 °, 25 ° is a highlight, a large light receiving angle θ ₃ such as 75 °, 110 ° is a shade, and a light receiving direction 14 such as 45 ° is close to the normal direction 13. The angle θ ₃ is called a face. For example, the incident angle θ ₁ may be within the range of 45 ° ± 5 ° (40 to 50 °), and the light receiving angle θ ₃ may be within the range of 45 ° ± 5 ° (40 to 50 °). Examples of the tolerance of the set angle include 0.1 ° and 0.2 °.
Brightness can be measured using a colorimeter such as a multi-angle spectrophotometer.

(Evaluation of metallic feeling)
When calculating the ratio between the mirror surface gloss and the brightness, the result of performing certain operations such as addition, subtraction, multiplication, and power of a constant on the ratio value may be used for evaluation. Since the specular glossiness is obtained by photometry in the specular reflection direction, the greater the contribution of specular reflection, the larger the value. Further, the brightness at an angle away from the specular reflection direction becomes larger as the contribution of diffuse reflection is larger. If it is a flat mirror-like metal material, the regular reflection is strong and the diffuse reflection is weak. Therefore, when the ratio of (specular gloss / brightness) is taken, the larger the value, the more metallic the visual feeling. A high value is preferable because it is easy to evaluate intuitively.

The design surface 10 may have a metallic coating film or may have a metal layer such as a metal foil. Metallic coatings include scaly metal pigments such as aluminum, copper, nickel alloys, and stainless steel, scaly metal pigments whose surface is coated with a metal oxide, scaly metal pigments whose surface is chemically adsorbed with a coloring pigment, and on the surface. Examples thereof include a coating film containing a metal particle pigment such as a scaly aluminum pigment in which an aluminum oxide layer is formed by causing an oxidation-reduction reaction. Examples of the metal layer include a metal foil, a metal vapor deposition layer, and a metal plating layer.

The paint (metallic paint) for forming a metallic coating film can be prepared by blending a vehicle, a pigment, a solvent (organic solvent, water, etc.) and, if necessary, an appropriate additive, and uniformly dispersing them. it can. Further, the metallic paint may include a general brilliant paint or a coloring pigment as a pigment other than the metal particle pigment. The color of the metallic coating film is not limited to silver, and may be tinged with colors such as red, blue, yellow, and green.

Glitter pigments include plate-shaped iron oxide pigments in which aluminum is dissolved, glass flake pigments, glass flake pigments whose surface is coated with metal or metal oxide, glass flake pigments whose surface is chemically adsorbed with colored pigments, and surfaces. Interfering mica pigment coated with titanium dioxide, reduced mica pigment obtained by reducing the interfering mica pigment, colored mica pigment with a colored pigment chemically adsorbed on the surface, colored mica pigment with the surface coated with iron oxide, and the surface coated with titanium dioxide. Examples thereof include graphite pigments, silica flakes and alumina flake pigments whose surfaces are coated with titanium dioxide, plate-shaped iron oxide pigments, hologram pigments, synthetic mica pigments, cholesteric liquid crystal polymer pigments having a spiral structure, and bismuth oxychloride pigments.

Color pigments include, for example, transparent iron oxide pigments, inorganic pigments such as composite oxide pigments such as titanium yellow; azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, and benz. Organic pigments such as imidazolone pigments, isoindolin pigments, isoindolinone pigments, metal chelate azo pigments, phthalocyanine pigments, anthracinone pigments, dioxazine pigments, slene pigments, indigo pigments, carbon black pigments, Examples include titanium oxide pigments.

Examples of the vehicle include a resin component. Specifically, the resin components include a base resin such as an acrylic resin, a polyester resin, an alkyd resin, and a urethane resin having a crosslinkable functional group such as a hydroxyl group, and a melamine resin, a urea resin, and a polyisocyanate compound (also a block body). Including) and the like in combination with a cross-linking agent.

The method for producing the coating film is not particularly limited as long as it can coat a bright paint having a uniform film thickness on the substrate, but a spray method such as air spray, airless spray, or electrostatic spray is preferable. .. When the design surface 10 is formed on the substrate, a coating film with an undercoat paint or an intermediate coating paint can be formed in advance on the substrate before the paint is applied. Further, on the coating film of the brilliant paint, one layer or two or more layers of the clear coating film can be formed for the purpose of protecting the coating film.

When flakes with a high aspect ratio are used as the metal particle pigment, such as a vapor-deposited aluminum pigment having a particle size (major diameter) of 10 μm or more and a thickness (minor diameter) of 0.1 μm or less (for example, about 0.05 μm). , The metallic feeling can be improved. However, if the orientation of the metal particles is not aligned with the surface direction of the coating film, the specular reflection direction of each flake is difficult to match with the specular reflection direction of the design surface even if the amount of reflected light emitted from the coating film is high. If there is a variation in the direction in which it looks bright to the naked eye, the directivity of the reflected light is lowered, and the metallic feeling like a flat metal material is lowered.

In recent years, attention has been paid to supermetal-like designs that are closer to metal materials than conventional metal-like designs, and super-metal-like coating colors that can realize this with a coating film. Examples of the design that can be evaluated as having the highest metallic feeling include a metal material polished in a mirror surface, a metal foil, a metal vapor deposition film, and metal plating. However, metal materials are heavy and tend to be avoided from the viewpoint of energy efficiency improvement and light weight in transportation equipment such as automobiles and portable equipment. Metal leaf is expensive to apply and stamp. Forming a metal vapor deposition film or metal plating on the surface of a molded part is also expensive, and depending on the shape and dimensions of the molded part, it may be difficult to perform vapor deposition or plating.

Therefore, it is required to realize a design having a high metallic feeling by painting (coating film), and an objective index of the metallic feeling is required. When a plurality of skilled observers make a visual evaluation, it is possible to make a high-level evaluation according to the human visual sensation, but it takes time to train the observer, and the influence of the observer's fatigue and physical condition, etc. Also need to be considered.

As a result of investigating the reflection characteristics of a uniform metal surface such as a metal material, a metal foil, and a metal vapor deposition film, the present inventors have found that the angle dependence of the reflectance is that the reflectance of positively reflected light is the highest and the light receiving angle is high. It was found that the reflectance decreases as the distance from the normal reflection direction increases, and that the brightness decreases significantly even when the light receiving angle is as small as about 15 ° (the light receiving direction is close to the normal reflection direction). It is conceivable to measure the brightness at a low angle such as 5 to 10 °, but a special measuring instrument is required and the measurement takes time. Therefore, by utilizing the specular glossiness obtained by measuring the specularly reflected light, it is possible to easily measure the characteristics of a design having a high metallic feeling.

According to the ratio of the mirror surface glossiness to the brightness described above, the decrease in metallic feeling (increase in graininess) due to poor orientation of metal particles can be reflected more highly than the conventional parameters, and the design has a high metallic feeling. It is useful for the development and evaluation of. From conventional metal-like designs to super-metal-like designs and metal materials, the visual metallic feeling can be evaluated by a unified index. Since the results consistent with the visual evaluation are obtained from simple parameters independent of the visual evaluation, they can be easily applied to online inspections such as painting lines.

Hereinafter, the present invention will be specifically described with reference to Examples. Further, "part" means "part by mass". The present invention is not limited to these examples.

(1) Production of hydroxyl group-containing acrylic resin 50 parts of ethylene glycol monoethyl ether acetate was charged into a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device, stirred and mixed, and the temperature was raised to 135 ° C. .. Next, 38 parts of methyl methacrylate, 17 parts of ethyl acrylate, 17 parts of n-butyl acrylate, 7 parts of hydroxyethyl methacrylate, 20 parts of lauryl methacrylate, 1 part of acrylic acid and 2,2'-azobis (2-methylpropionitrile) 2 A mixture of monomer / polymerization initiator consisting of parts was added dropwise to a reaction vessel kept at the same temperature over 3 hours, and the mixture was aged for 1 hour after completion of the addition.
Then, a mixture consisting of 10 parts of ethylene glycol monoethyl ether acetate and 0.6 parts of 2,2'-azobis (2-methylpropionitrile) was added dropwise to a reaction vessel kept at the same temperature over 1 hour and 30 minutes. , Aged for another 2 hours.
Next, unreacted ethylene glycol monoethyl ether acetate was distilled off under reduced pressure to obtain a hydroxyl group-containing acrylic resin having a hydroxyl value of 54 mgKOH / g, a number average molecular weight of 20,000, and a resin solid content of 65% by mass. Here, the number average molecular weight means that measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.

(2) Production of Organic Solvent Paint 1 Consists of 75 parts of the hydroxyl group-containing acrylic resin obtained in (1) and 25 parts of Uban (registered trademark) 28-60 (trade name, butyl etherified melamine resin, manufactured by Mitsui Chemicals, Inc.). 10 parts of aluminum paste GX-180A (trade name, manufactured by Asahi Kasei Aluminum Co., Ltd., solid content 74% by mass, scaly aluminum pigment paste having a primary average particle diameter of 16.9 μm) per 100 parts (solid content) of the resin component. The mixture was mixed, stirred and mixed, and diluted to a viscosity suitable for coating to prepare an organic solvent type coating material 1 having a solid content of about 25%.

(3) Production of Organic Solvent Paint 2 Consists of 75 parts of the hydroxyl group-containing acrylic resin obtained in (1) and 25 parts of Uban (registered trademark) 28-60 (trade name, butyl etherified melamine resin, manufactured by Mitsui Chemicals, Inc.). 30 parts of aluminum paste GX-180A (trade name, manufactured by Asahi Kasei Aluminum Co., Ltd., solid content 74% by mass, scaly aluminum pigment paste having a primary average particle diameter of 16.9 μm) per 100 parts (solid content) of the resin component. The mixture was mixed, stirred and mixed, and diluted to a viscosity suitable for coating to prepare an organic solvent type coating material 2 having a solid content of about 25%.

(4) Production of Organic Solvent Paint 3 Consists of 75 parts of the hydroxyl group-containing acrylic resin obtained in (1) and 25 parts of Uban (registered trademark) 28-60 (trade name, butyl etherified melamine resin, manufactured by Mitsui Chemicals, Inc.). For every 100 parts (solid content) of the resin component, 10 parts of METASHEEN (registered trademark) 71-0010 (trade name, manufactured by BASF, 10% by mass of solid content, vapor-deposited aluminum slurry) is mixed as a solid content, mixed by stirring, and coated. The organic solvent type coating material 3 having a solid content of about 12% was prepared by diluting to an appropriate viscosity.

(5) Production of thin-film vapor-deposited aluminum pigment solution Butyl acetate was added to METASHEEN (registered trademark) 71-0010 (trade name, manufactured by BASF, solid content 10% by mass, vapor-deposited aluminum slurry) and mixed by stirring to obtain a solid content of 0. A 5 mass% vapor-deposited aluminum pigment solution was prepared.

(6) Preparation of base material for coated plate The cationic electrodeposition paint "Epoxy (registered trademark) 9400HB" (trade name: Kansai) is applied to a steel plate (JIS G 3141, size 400 mm x 300 mm x 0.8 mm) that has been degreased and treated with zinc phosphate. An epoxy resin polyamine-based cationic resin manufactured by Paint Co., Ltd. using a block polyisocyanate compound as a curing agent) is electrodeposited based on a cured coating film to a thickness of 20 μm, and heated at 170 ° C. for 20 minutes. Crosslinking and curing gave an electrodeposition coating.
On the obtained electrodeposited surface, apply the intermediate coating "Lugabake (registered trademark) intermediate coating N-2 gray" (trade name: Kansai Paint Co., Ltd., polyester resin / melamine resin, organic solvent type) by air spray. Based on the cured coating film, the coating was applied so as to have a film thickness of 30 μm, and the coating plate was heated at 140 ° C. for 30 minutes to be crosslinked and cured to form an intermediate coating film, which was used as a base material.

(7) Preparation of coating plate for evaluation (Sample 1)
The organic solvent type coating material 1 obtained in (2) is coated on the base material obtained in (5) using an air spray so as to have a dry film thickness of 15 μm, and after coating, 15 at room temperature. After leaving it for a minute, "Lugabake (registered trademark) clear" (trade name, manufactured by Kansai Paint Co., Ltd., acrylic resin / amino resin type, organic solvent type) was applied to the booth temperature 25 using a mini bell type rotary electrostatic coating machine. A cured coating film was applied under the conditions of ° C. and humidity of 75% so as to have a film thickness of 30 μm. After coating, the mixture was left at room temperature for 15 minutes and then heated at 140 ° C. for 30 minutes using a hot air circulation drying furnace to simultaneously dry and cure the multi-layer coating film to prepare a coating plate to be used for measurement.

(Sample2)
The organic solvent type coating material 2 obtained in (3) is coated on the base material obtained in (5) using an air spray so as to have a dry film thickness of 5 μm. After leaving it for a minute, "Lugabake (registered trademark) clear" (trade name, manufactured by Kansai Paint Co., Ltd., acrylic resin / amino resin type, organic solvent type) was applied to the booth temperature 25 using a mini bell type rotary electrostatic coating machine. A cured coating film was applied under the conditions of ° C. and humidity of 75% so as to have a film thickness of 30 μm. After coating, the mixture was left at room temperature for 15 minutes and then heated at 140 ° C. for 30 minutes using a hot air circulation drying furnace to simultaneously dry and cure the multi-layer coating film to prepare a coating plate to be used for measurement.

(Sample3)
The organic solvent-type coating material 3 obtained in (4) is coated on the substrate obtained in (6) using an air spray so as to have a dry film thickness of 2 μm. After leaving it for a minute, "Lugabake (registered trademark) clear" (trade name, manufactured by Kansai Paint Co., Ltd., acrylic resin / amino resin type, organic solvent type) was applied to the booth temperature 25 using a mini bell type rotary electrostatic coating machine. A cured coating film was applied under the conditions of ° C. and humidity of 75% so as to have a film thickness of 30 μm. After coating, the mixture was left at room temperature for 15 minutes and then heated at 140 ° C. for 30 minutes using a hot air circulation drying furnace to simultaneously dry and cure the multi-layer coating film to prepare a coating plate to be used for measurement.

(Sample4)
On the base material obtained in (6), the vapor-deposited aluminum pigment solution obtained in (5) was used, and W-101-102P (air spray gun, manufactured by Anest Iwata Co., Ltd.) was used to set the paint adjustment knob to 0. Under the conditions of 5 rotations open, sprayed air pressure 0.2 MPa, gun distance 30 cm, gun speed 10 cm / s, one stage was painted, and after painting, left at room temperature for 15 minutes, "Lugabake (registered trademark) clear" ( Product name, Kansai Paint Co., Ltd., acrylic resin / amino resin type, organic solvent type), using a mini bell type rotary electrostatic coating machine, as a film as a cured coating film under the conditions of booth temperature 25 ° C and humidity 75%. It was painted so as to have a thickness of 30 μm. After coating, the mixture was left at room temperature for 15 minutes and then heated at 140 ° C. for 30 minutes using a hot air circulation drying furnace to simultaneously dry and cure the multi-layer coating film to prepare a coating plate to be used for measurement.

(Sample5)
On the base material obtained in (6), the vapor-deposited aluminum pigment solution obtained in (5) was used, and W-101-102P (air spray gun, manufactured by Anest Iwata Co., Ltd.) was used to set the paint adjustment knob to 0. Two-stage coating was performed under the conditions of 5 rotations open, sprayed air pressure 0.2 MPa, gun distance 30 cm, and gun speed 10 cm / s, and after painting, left at room temperature for 15 minutes, and then "Lugabake (registered trademark) clear" ( Product name, Kansai Paint Co., Ltd., acrylic resin / amino resin type, organic solvent type), using a mini bell type rotary electrostatic coating machine, as a film as a cured coating film under the conditions of booth temperature 25 ° C and humidity 75% It was painted so as to have a thickness of 30 μm. After coating, the mixture was left at room temperature for 15 minutes and then heated at 140 ° C. for 30 minutes using a hot air circulation drying furnace to simultaneously dry and cure the multi-layer coating film to prepare a coating plate to be used for measurement.

(Sample6)
On the base material obtained in (6), the vapor-deposited aluminum pigment solution obtained in (5) was used, and W-101-102P (air spray gun, manufactured by Anest Iwata Co., Ltd.) was used to set the paint adjustment knob to 0. Under the conditions of 5 rotations open, sprayed air pressure 0.2 MPa, gun distance 30 cm, gun speed 10 cm / s, 5 stages were painted, and after painting, left at room temperature for 15 minutes, then "Lugabake (registered trademark) clear" ( Product name, Kansai Paint Co., Ltd., acrylic resin / amino resin type, organic solvent type), using a mini bell type rotary electrostatic coating machine, as a film as a cured coating film under the conditions of booth temperature 25 ° C and humidity 75%. It was painted so as to have a thickness of 30 μm. After coating, the mixture was left at room temperature for 15 minutes and then heated at 140 ° C. for 30 minutes using a hot air circulation drying furnace to simultaneously dry and cure the multi-layer coating film to prepare a coating plate to be used for measurement.

(Sample7)
On the base material obtained in (6), the vapor-deposited aluminum pigment solution obtained in (5) was used, and W-101-102P (air spray gun, manufactured by Anest Iwata Co., Ltd.) was used to set the paint adjustment knob to 0. Under the conditions of 5 rotations open, sprayed air pressure 0.2 MPa, gun distance 30 cm, gun speed 10 cm / s, 10 stages were painted, and after painting, left at room temperature for 15 minutes, "Lugabake (registered trademark) clear" ( Product name, Kansai Paint Co., Ltd., acrylic resin / amino resin type, organic solvent type), using a mini bell type rotary electrostatic coating machine, as a film as a cured coating film under the conditions of booth temperature 25 ° C and humidity 75%. It was painted so as to have a thickness of 30 μm. After coating, the mixture was left at room temperature for 15 minutes and then heated at 140 ° C. for 30 minutes using a hot air circulation drying furnace to simultaneously dry and cure the multi-layer coating film to prepare a coating plate to be used for measurement.

(Sample8)
After attaching household aluminum foil to a smooth tin plate and degreasing the foil surface with a solvent, "Lugabake (registered trademark) clear" (trade name, manufactured by Kansai Paint Co., Ltd., acrylic resin / amino resin type, organic solvent The mold) was coated with a mini-bell type rotary electrostatic coating machine as a cured coating film under the conditions of a booth temperature of 25 ° C. and a humidity of 75% so as to have a film thickness of 30 μm. After coating, the mixture was left at room temperature for 15 minutes and then heated at 140 ° C. for 30 minutes using a hot air circulation drying furnace to dry-cure the clear coating film to prepare a coating plate to be used for measurement.

(8) Evaluation of coated plate (measurement of brightness)
Using MA68II (trade name, multi-angle spectrophotometer, manufactured by X-Lite), the color of the design surface of the coated plate obtained in (7) was measured, and the Y value in the XYZ color system and L ^* a ^* B ^* The L ^* value in the color system was measured. The incident angle is 45 °, and the light receiving angles are 15 ° and 45 °.
Hereinafter, the Y value at a light receiving angle of 15 ° is represented by "Y ₁₅ ", the Y value at a light receiving angle of 45 ° is represented by "Y ₄₅ ", and the L ^* value at a light receiving angle of 15 ° is represented by "L ^* ₁₅ ". The L ^* value at an angle of 45 ° is represented by "L ^* ₄₅ ".

The flip-flop value "FF" was calculated by the following formula.
FF = 2 × (Y _15- Y ₄₅ ) / (Y ₁₅ + Y ₄₅ )

(Measurement of mirror gloss)
Using a micro-tri-gloss (trade name, gloss meter, manufactured by BYK Gardner), the design surface of the coated plate obtained in (7) is irradiated with light from an incident angle of 60 ° and specularly reflected. Light was received and the mirror glossiness was measured. The mirror glossiness at an incident angle of 60 ° is represented by "Gs ₆₀ ".
Further, the values of "Gs ₆₀ / Y ₄₅ " and "Gs ₆₀ / L ^* ₄₅ " were calculated by dividing the value of the mirror glossiness Gs _{60 by} the value of the brightness Y ₄₅ or L ^* ₄₅ .

(Measurement of micro-brightness data)
Image data of the design surface of the coated plate was acquired using an imaging device, and from the acquired image data, "HG" and "SB", which are data representing micro-brilliance, were calculated by the following formulas.

When IPSL ≧ 0.32, HG = 500 · IPSL-142.5
When 0.32> IPSL ≧ 0.15, HG = 102.9 · IPSL-15.4
If 0.15> IPSL, HG = 0

HB = (BV-50) / 2

Here, IPSL and BV are calculated by the following equations.

IPSL = ∫ ₀ ^N ∫ ₀ ^2π P (ν, θ) dνdθ / P (0,0)
BV = PH _av + 350PS _av

Here, P (ν, θ) is a power spectrum obtained by performing a two-dimensional Fourier transform process on the two-dimensional luminance distribution data generated from the acquired image data, ν is a spatial frequency, and θ is an angle. 0 to N are spatial frequency regions corresponding to the feeling of particles. ∫ ₀ ^N dν is the integral in the spatial frequency domain _{0 to} ^N , and ∫ ₀ ^2π dθ is the integral in the angular domain _{0 to} ^2π .

Further, PH _av and PS _av are the average peak height and the average peak skirt spread ratio of the luminance image, respectively, and PH _av = 3V / A and PS _av = L / PH _av . Here, V and A are the total luminance volume and the total luminance area above the threshold value when binarized with the threshold value of “GL + 32”, respectively, and L is the average grain size when binarized with the threshold value of “GL + 24”. The diameter. Here, GL is the average gray level of the image data.

The results are shown in Tables 1 and 2. The visual metallic feeling was ranked by visual inspection by a skilled worker, with a general silver paint score of 1 and an aluminum foil score of 5.
The concealing properties of samples 4 to 7, which are the coating films of the vapor-deposited aluminum pigment liquid, improved as the number of stages increased, and the sample 7 did not give the impression of being transparent visually. The visual score of samples 4 to 7 was set to 4. In Table 1, score 4 is represented by sample 7, and in Table 2, samples 4 to 7 can be compared.

Comparing the L ^* ₁₅ value with the visual score, there is no correlation, and the L ^* ₁₅ value of aluminum foil is lower than the general silver paint color. Similarly, the FF value is different from the visual score.
Regarding the Gs ₆₀ value, which is the measurement result of specular light, the value of aluminum foil was the largest among the eight types of samples. Therefore, by taking a ratio of Gs ₆₀ / L ^* ₄₅ , a result consistent with the visual metallic feeling was obtained. In addition, according to the ratio of Gs ₆₀ / Y ₄₅ , the value of aluminum foil was close to 100, and the order of metallic feeling could be quantified more easily. Therefore, by taking the ratio of the mirror glossiness to the brightness, such as Gs ₆₀ / L ^* ₄₅ and Gs ₆₀ / Y ₄₅ , parameters that can quantify the metallic feeling by a simple measurement method were obtained.

As shown in Table 2, for samples 4 to 7 (the number of painting stages is 1, 2, 5, and 10, respectively), there was no clear difference in the FF value, which is a conventional parameter, but Gs ₆₀ / L ^* _45. According to the ratio of Gs ₆₀ / Y _45, the smaller the number of coating stages, the larger the ratio value and the higher the metallic feeling. Regarding the brightness of highlights (for example, the light receiving angle is 15 °), the larger the number of painting stages, the larger the value of L ^* ₁₅ , and the apparently whiter. However, as the number of coating stages increased, the orientation of the aluminum flakes used as the vapor-deposited aluminum pigment in the coating film was disturbed, so that the value of the mirror surface gloss Gs ₆₀ became smaller.

As for the brightness of the face (for example, the light receiving angle is 45 ° ± 5 °), the value of L ^* ₄₅ increased and the brightness increased as the concealing property by the coating film increased due to the increase in the number of coating stages. The brightness of the shade (for example, the light receiving angle is 75 ° to 110 °) does not show any particular measurement result, but is considered to show the same tendency.

The apparent metallic feel is more appreciated by observing the brightness of the highlight and the blackness of the face or shade at the same time. Of the samples 4 to 7, sample 4 has the highest metallic feel and sample 7 has the highest metallic feel, because it is considered that the metallic feel is high not only when the highlight is bright (white) but also when the face or shade is dark (black). It can also be evaluated that the metallic feeling is low. That is, according to the results in Table 2, as in Gs ₆₀ / L ^* ₄₅ and Gs ₆₀ / Y ₄₅ , by taking the ratio of the mirror surface glossiness to the brightness, the difference in the visual metallic feeling is small, samples 4 to 7. Even during that time, we were able to obtain and evaluate numerical values close to the feeling of metal.

10 ... design surface, 11 ... incident direction, 12 ... specular reflection direction, 13 ... normal direction, 14 ... light receiving direction.

Claims (4)

The mirror glossiness of the design surface having a metallic design measured with an incident angle of 60 ° ± 5 ° and the incident angle of the design surface of 45 ° ± 5 ° are 45 ° from the regular reflection direction to the incident direction. A method for evaluating a metallic design, which comprises calculating a ratio to a brightness measured with an angle of ± 5 ° as a light receiving angle, and evaluating the metallic design by the ratio. The brightness, the brightness _Y in the XYZ color system, _{X 10 Y} 10 brightness _Y 10 in _{Z 10} color ^system, L ^* a * ^{b *} color system or ^L * ^u * ^{v *} in the lightness ^{L *} color system The method for evaluating a metallic design according to claim 1 , wherein the metallic design is either of the above. The method for evaluating a metallic design according to claim 1 , wherein the lightness is the lightness Y in the XYZ color system. The method for evaluating a metallic design according to any one of claims 1 to 3 , wherein the design surface has a metallic coating film or a metal layer.

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