JPH10170436A - Method for quantitative evaluation of luminosity of coated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance correlation to a visually evaluated result and quantitatively evaluate a luminosity of a coated film containing a luminous material, by subtracting a specific threshold value from each luminance of a segment divided from an image and summing positive subtracted values. SOLUTION: An artificial sun light 10 (metal halide lamp) is used as a light source and an image is captured by a CCD camera 12. The image transmitted from the camera 12 is divided to a plurality of pixels at an image-analyzing apparatus 14, and a luminance I of each pixel is measured. In other words, the image is split to many segments and the image luminance I of each segment is measured. A threshold value α which is 1.05-1.50 times an average luminance is obtained from a total value of the luminances I of all segments. The threshold value is subtracted from the luminance I of each segment. Positive ones of the subtracted values of all segments are summed to obtain a total luminance S, while negative values are set to 0. A luminosity of a coated film containing a luminous material is quantitatively evaluated based on the total luminance S.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for quantitatively evaluating the glitter of a glitter-containing coating film.

[0002]

2. Description of the Related Art In order to enhance the design of a paint film, a metallic finish using a paint containing a glittering material such as flaky aluminum or mica powder is often used instead of a solid color finish. I have.

As criteria for evaluating the appearance of the coating film, for example, Group A: surface shape and surface layer physical properties such as glossiness and smoothness, Group B: transparency, depth, two-layered feeling, and feeling of fullness And the group C: orientational structure in the coating film such as shadow feeling and glittering feeling.

It is an object of the present invention to quantify an evaluation method relating to the “brilliance” of Group C, which is important in a glitter material-containing coating film.

Heretofore, as a method for quantitatively evaluating the glitter of a glitter-containing coating film, it is known to use a laser-type measuring device, a device using a microgloss meter, or the like.

The laser type measuring device irradiates the surface of the coating film containing the luminous material with laser light, and accumulates the difference in the average amount of reflected light at a plurality of light receiving angles and the change in the amount of reflected light when scanning. However, it is difficult to evaluate the brilliancy due to the interference effect in a brilliant-containing coating film containing an interference pigment such as mica powder as the brilliant because the irradiation light has almost a single wavelength. . The microscopic gloss meter apparatus evaluates based on the L value calculated from the reflected light intensity data in the fine area of the coating film, but has a defect that the correlation with the result of the visual evaluation is low.

[0007]

The present invention solves the above-mentioned defects and can be applied to a coating film containing an interference pigment as a glittering material, and has a high correlation with a visual evaluation result. The present invention relates to a method for quantitatively evaluating the brilliant feeling of the object.

According to the present invention, in order to solve the above-mentioned problems, light is applied to the surface of the coating film containing the brilliant material, and the coated surface to which the light is applied is applied at an angle at which the specularly reflected light is not incident.
Photographing with a CD camera and obtaining the image, dividing the image into a number of sections, measuring the brightness I of the image in each of the sections, and calculating the brightness I of each of the sections through all of the sections To obtain a threshold value α that is 1.05 to 1.50 times the average luminance x, and subtract the threshold α from each luminance I of the section. Then, subtracting the subtracted value is a positive value over all the sections to obtain a total luminance S, and quantitatively evaluating the glitter of the glittering material-containing coating film according to the total luminance S. And a method for quantitatively evaluating the glitter of a coating film.

The method for quantitatively evaluating the glitter of the glitter-containing coating film of the present invention will be specifically described below.

Examples of the "glitter-containing coating" (hereinafter referred to as "metallic coating") applicable to the method of the present invention include, for example, flaky aluminum powder, mica-like iron oxide, mica powder, and metal oxide-coated mica. A single-layer coating film containing a metallic pigment having a glittering or interference effect such as a powder (1); a single-layer coating film (2) comprising a combination of these metallic pigments and a solid color pigment in the same coating film; ), A multi-layer coating film (1) obtained by laminating the single-layer coating film (1) or the single-layer coating film (2) on a solid color-colored coating film, a single-layer coating film or a multi-layer coating film And a multi-layer coating film (2) obtained by further applying a clear coating on the surface.

These glitter-containing coating films are prepared by mixing and dispersing, for example, a thermosetting, thermoplastic, or room-temperature curable resin composition known per se with a metallic pigment and, if necessary, a solid color coloring pigment. The organic solvent-based or water-based paint is applied directly to a metal or plastic substrate (for example, an outer panel of an automobile, etc.) or by undercoating or further intermediate coating, followed by coating [(single layer Coating (1), single-layer coating (2)] The solid color-colored coating [multilayer coating (1)] or the upper layer on the lower layer side of these single-layer coatings (1) or (2) And a multi-layer coating film (2) formed by applying a clear coating material to the film.

In the present invention, first, the surface of the bright material-containing coating film is irradiated with light. This light is preferably simulated (artificial) sunlight, and as this light source, for example, a metal halide lamp is suitable. The light irradiation angle on the surface of the glittering material-containing coating film is preferably within a range of 45 ° ± 10 ° based on the vertical line of the coated surface, and particularly preferably 45 ° with respect to the vertical line. The light irradiation area (measurement range) is 1 to 100 mm × 1 to 100 mm of the coated surface.
mm is suitable, but not limited thereto. The illuminance of the light source is preferably 1000 to 5000 lux.

Thus, the surface of the coating material containing the glittering material is irradiated with light,
Of the reflected light based on the light, the painted surface irradiated with the light at an angle at which the regular reflected light is not incident is CCD (Charge).
Shoot with a Couple Device) camera. This shooting angle may be any angle at which specularly reflected light does not enter,
The direction perpendicular to the painted surface is particularly preferred. Further, the angle between the shooting direction of the CCD camera and the specularly reflected light is preferably 35 to 55 degrees.

In the method of the present invention, the CCD camera is connected to an image analysis device, and an image taken by the CCD camera is analyzed by this device. As this image analyzer, for example, “LUZEXIII” (trade name) manufactured by Nireco Co., Ltd. is suitable.

In an image analyzer, an image transmitted from a CCD camera is converted into a plurality of pixels (typically 10,000 to 100).
0000), and the luminance at each can be measured. That is, the pixel portion containing the metallic pigment has a high luminance level because of the strong glittering and interference effects, and the pixel portion not containing the pigment naturally has a low luminance level. Even if a metallic pigment is included, the luminance level may vary depending on the size, shape, angle, material, and the like. That is, the luminance level can be displayed for each pixel. According to the present invention, it is possible to three-dimensionally display the distribution of the luminance level of the painted surface photographed by the CCD camera based on the luminance level of each pixel. This three-dimensional distribution map is divided into peaks, valleys, and flat areas, and the height and size of the peaks indicate the degree of glitter caused by the metallic pigment, and the higher the peak, the more remarkable glitter and interference effect , Valleys and flat areas show reflection mainly due to the solid color coloring pigment.

The present invention quantitatively evaluates the glitter of a glitter-containing coating based on the luminance level of each pixel obtained by the image analyzer.

The luminance level (I) of each pixel and the average luminance level (x) of all pixels are obtained, and the expression Σ (I
The data obtained by -x) had low correlation with the result of visual observation, and was insufficient as an objective evaluation method.

Therefore, in the present invention, only the brilliant feeling such as the glittering effect or the interference effect is extracted from the luminance level (I) for each pixel, and the total is defined as the total luminance (S). The threshold (α) indicating the boundary between the two, which cuts the part other than the glitter, was examined. As a result, they found that the larger the threshold (α) was than the average luminance level (x), the better the correlation with the visual observation result was,
Further studies revealed that the threshold (α) was 1.05x ~
1.50x was found to be optimal and completed the present invention.

That is, the luminance level (I) for each pixel
And the average luminance (x) thereof was determined, and the luminance was evaluated by the total luminance (S) obtained by applying the average luminance (x) to the following equation. As a result, the logarithm of the total luminance (S) was Log.
(S) and the result of visual observation showed a good correspondence.

S = Σ [(I) -α] In the formula, α is equal to or greater than 1.05x, particularly 1.05 to 1.
5x is suitable, and the result of evaluation based on the logarithm Log (S) of the total luminance (S) thus determined has a high correlation coefficient with the result of visual observation, and is always 0.95 or more.

More specifically, first, light is applied to the surface of the coating film containing the brilliant material, and the coated surface to which the light is applied is photographed by a CCD camera at an angle at which the specularly reflected light is not incident, thereby obtaining an image. The CCD camera has, for example, 256 × 256 pixels. The luminance I is measured for each pixel. Thus, the image is divided into a number of sections, and the luminance I of the image in each of the sections is measured.

The luminance I measured at each of the pixels is summed over all to obtain a total value, and from this total value, a threshold α which is a value of 1.05 to 1.50 times the average luminance x is obtained. For example, the total value is divided by the number of pixels to obtain an average luminance x. The threshold value α is obtained by multiplying the average luminance x by a constant between 1.05 and 1.50.

The threshold value α is subtracted from the luminance I of each pixel. If the subtraction value is negative, it is set to 0, and only the subtraction value whose subtraction value is a positive value is summed over all the pixels. Obtain the luminance S.

According to the total luminance S, the glitter of the glitter-containing coating film is quantitatively evaluated.

[0025]

Embodiments of the present invention will be described below in detail.

In this example, the glitter of a coating film (FIG. 1) using mica powder as a metallic pigment was measured.

The measuring device is as shown in FIG. 2 and includes simulated (artificial) sunlight 10 as a light source, a CCD camera 12 for capturing an image, and an A / A
It comprises an image analyzer 14 for D-conversion and a personal computer for controlling and managing the image analyzer.

As samples, five test panels of a coating film (FIG. 1) using mica powder as a metallic pigment were prepared. In these five test panels, the thickness of the metallic pigment-containing coating film and the coating conditions were varied, and the glitter of the metallic pigment (mica powder) was varied. The color of the solid color colored coating film is the same in light gray. The coating uses a thermosetting resin coating.

First, the five test panels were subjected to a sensory evaluation of glitter. As the evaluation conditions, five test panels were evaluated outdoors at an angle at which regular reflection light was not incident by five persons involved in coating by a paired comparison method (five-level evaluation). Based on the results, the test panels were ranked, and the resulting panels were ranked as glitter in sensory evaluation. This is shown in FIG. In FIG. 3, the arrow indicates the yardstick Y.
(0.05).

Next, the brightness of the five test panels (A to E) was measured according to the present invention. As a measuring instrument, "metal halide lamp" (color temperature 5600K, color rendering index 98) was used as the simulated (artificial) sunlight 10, and "LUZEXIII" (manufactured by Nireco Co., Ltd.) was used as the image analyzer 14.

The measurement conditions are as shown in FIG. The angle between the simulated sunlight 10 and the CCD camera 12 is 45 degrees, and the CCD
The camera and test panel were vertical. The illuminance was 3000 lux on the test panel surface.

As an image analysis, the average luminance level of the mirror-surfaced white magnetic plate (60 ° gloss value: 92) was set to 256.
Is divided into 256 gradations. The measurement surface was 1 mm × 1 mm, which was decomposed into 256 × 256 pixels for data processing.

One of the five samples (hereinafter, sample A) is measured under the above conditions. As a result, a luminance level (I) of a part (1 mm × 1 mm) of the sample A is obtained for each pixel (65536 pixels).

FIG. 5 shows a three-dimensional luminance distribution created from the obtained luminance level (I). The size of the three-dimensional luminance distribution indicates the area of the measurement surface (256 × 256 pixels), and the height indicates the luminance level (I). In this figure, a high part of a mountain is a part with high glitter. Therefore,
A threshold value (α) is set to separate a portion having high glitter from other portions. That is, the volume of the white portion in FIG. 6 is obtained.
First, the sum of the luminance levels (I) (Σ (I)) [9648
210] divided by the total number of pixels [65536], and the average luminance x [147.22] is calculated. Next, the average luminance x is multiplied by 1.05 to obtain a threshold value (α) [154.59].
Is calculated. After that, for each pixel, a portion of the luminance (I) equal to or more than the inner threshold (α), that is, the sum of (I) − (α)） ((I) − (α)) [6981] is calculated. However,
When (I)-(α) is a negative value, it is set to 0. This is the total luminance (S) of the sample A. Similarly, the total luminance (S) was similarly calculated for the other four sheets. The results are as shown in Table 1 below.

[0035]

[Table 1]

FIG. 7 is a graph showing the relationship between the light luminance rank of the sensory evaluation and the total luminance (S) obtained so far. The logarithm Log (S) of the total luminance (S) and the glitter rank of the sensory evaluation showed a very good correspondence.
(Correlation coefficient 0.974, contribution ratio 94.9%) Here, when the threshold (α) is not set to 1.05x (x: average luminance) and x is set to the threshold, the correspondence with the sensory evaluation is shown in FIG. Become like
In this case, the correlation coefficient is 0.910 and the contribution ratio is 82.8%, and the correlation is reduced. This is because if the threshold value is the average luminance, the effects of the reflected light of the solid color coloring pigment, which is not related to the glitter, and the weak light that does not cause the glitter can not be completely eliminated.

[Brief description of the drawings]

FIG. 1 is an example of a coating film whose glitter is evaluated by the method of the present invention.

FIG. 2 shows a measuring device that can be used in the method of the present invention.

FIG. 3 is a diagram showing a glitter rank in sensory evaluation.

FIG. 4 is a diagram showing measurement conditions of a measurement device that can be used in the method of the present invention.

FIG. 5 is a diagram showing a three-dimensional luminance distribution obtained as a result of the measurement.

FIG. 6 is a diagram showing a three-dimensional luminance distribution and a threshold obtained as a result of the measurement.

FIG. 7 is a graph showing the correspondence between the light luminance rank in sensory evaluation and the total luminance (S) when the threshold (α) is set to 1.05x.

FIG. 8 is a graph showing the correspondence between the brightness rank of sensory evaluation and the total brightness (S) when the threshold (α) is x.

[Explanation of symbols]

 10 Artificial sunlight 12 CCD camera 14 Image analyzer

Claims (1)

[Claims] 1. A method of irradiating a light-emitting material-containing coating film with light, and applying a light-irradiated coating surface at an angle at which specularly reflected light is not incident.
Photographing with a D-camera and obtaining the image; dividing the image into a number of sections; measuring the brightness I of the image in each of the sections; To obtain a total value, from which the average luminance x of 1.0
Subtracting the threshold value α from the luminance I of each of the sections, and subtracting the positive value of the subtraction value over all of the sections to obtain a threshold value α that is a value of 5 to 1.50. Obtaining a total brightness S, and quantitatively evaluating the glitter of the glitter-containing coating according to the total brightness S.