JP3457419B2 - Method for estimating the type of brilliant and its composition in brilliant-containing coatings by optical measurement - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating a coating material containing a bright material by optical measurement.

[0002]

2. Description of the Related Art In recent years, a coating material containing a glittering material containing a glittering material has been widely used as a highly decorative coating color for automobile outer panel colors and the like. The bright material-containing coating uses a scaly bright pigment such as aluminum or mica, and the bright feeling, interference color, etc. differ depending on the type of the bright material, the fineness, and the degree of orientation in the coating. , Gives a unique optical effect due to the reflected light distribution different from that of a coating film using only ordinary coloring pigments. In industrial coating, the orientation of the luster pigment in the coating film is within a generally controlled width due to the control of the coating line. Therefore, in industrial applications, particularly in automobile exterior coatings, the type of glittering material used (type and particle size) is a major determinant of the glittering feeling of the coating film.

Factors that characterize the metallic feeling of a metallic coating film containing a glittering material include brightness, glittering feeling (glittering feeling), and optical anisotropy (flop effect). Of these, brightness and optical anisotropy can be evaluated to some extent. However, with regard to the feeling of glitter, what and how to evaluate it was not known. The glittering feeling is caused by the strong reflected light from the glittering material particles, and changes depending on the type of the glittering material, the particle size, and the like.
By the way, even if the same kind of glitter material (for example, aluminum pigment) has different particle diameters, the glitter feeling is different. Therefore, for example, when a coating film is formed by mixing aluminum pigments having different particle diameters for metallic coating, various glitter feelings can be expressed. In the case where there is a coating film containing a plurality of luster pigments as described above, if the composition of the coating film can be estimated by optical measurement, it is possible to prepare a paint having the estimated composition and reproduce the coating color. Conventionally, an expert has empirically estimated the composition of a coating film that seems to use a plurality of luster pigments. If it is possible to estimate the glitter material type and its composition by optically measuring the paint color containing the glitter material, the paint color can be reproduced even if there is little experience, but hitherto it was not possible to estimate the composition by optical measurement.

It has been reported that the glitter feeling can be evaluated by measuring the distribution of the reflected light intensity in a fine area with a microscopic gloss meter and analyzing the waveform (peak height, pitch length, etc.). However, this method cannot be applied to mixed coating colors in which a plurality of luster pigments are mixed. Further, as a method for evaluating a coating film containing a glitter material, there is disclosed in Japanese Patent Laid-Open No. 6-17979.
In Japanese Patent Laid-Open No. 34-34, there is known a method for evaluating the feeling of coating depth of a coating film containing a glitter material. It is said that the feeling of depth is caused by reflection from the back of the coating film. Since the feeling of depth is assumed to be transparent, this method evaluates the feeling of depth by measuring the brightness of the coated surface while changing the thickness of the color clear layer. But,
The evaluation of the feeling of depth is a technical problem different from the estimation of the glitter material type and the blend in the same glitter material, which is the subject of the present invention.

An object of the present invention is to provide a method for estimating the composition of a glittering material in a glittering material-containing coating film by optical measurement.

[0006]

In the method for estimating the type of glitter material of a coating film containing a glitter material according to the present invention, light is applied to the surface of the coating film from a light source, and light is received from an angle at which specular reflection light does not enter. Then, the intensity of the reflected light from the fine area on the surface of the coating film is measured for the entire predetermined evaluation area, and the frequency distribution is obtained for the reflected light intensity data obtained by this measurement. Next, we use this frequency distribution as the function

N = aR _s exp (−R _s / (2b ² )) + C exp (− (R _s −D) ² / E) (1) (where N is the frequency at the reflected light intensity R _s ) Represents, a,
b, C, D and E are parameters obtained by calculation). Then, the roughness of the bright material in the coating film is estimated from the obtained parameter values. Preferably, the measurement of the reflected light intensity is performed using a micro gloss meter.

[0007]

In the present invention, the frequency distribution of the intensity of the reflected light is obtained by paying attention to the "unevenness of the reflected light in a fine area" of the coating material containing the glittering material. The behavior of the frequency distribution of reflected light intensity is the sum of a function suitable for expressing the peak part (most frequent value) of the frequency distribution and a function suitable for expressing the tail part of the frequency distribution on the high reflected light intensity side. It turned out that it can be expressed by a certain function model (1). From the parameters obtained by using this function model, it was found that it is possible to express the positional relationship between the single pigment and the mixed pigment of the same luster color material. As a result, it became possible to characterize the coating color containing the glittering material by analyzing the parameters, and nondestructively estimate the type of the glittering material in the coating film and its composition. Further, by using a micro gloss meter, the intensity of reflected light can be accurately measured.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the evaluation of luster material type and coarseness,
First, (1) Using a micro-gloss meter, irradiate a predetermined evaluation surface of the coating film with light, measure the intensity of reflected light for each minute unit area within the evaluation surface, and perform this operation for the entire predetermined evaluation area. Then, the distribution of the reflected light intensity over the entire evaluation area is measured. Next, (2) The frequency distribution is calculated for the obtained measurement data, and the behavior of this frequency distribution is expressed by a function model that is the sum of two functions. The composition is evaluated. These will be described in more detail below using examples. Needless to say, the feature of the present invention is that the luster material species in the coating film can be determined from the behavior of the frequency distribution of the reflected light intensity data obtained for the predetermined evaluation area of the coating material containing the luster material. The method of measuring the reflected light intensity data is not limited to the method described below. For example, a CCD camera may be used.

First, the nonuniformity of reflected light in a fine area of a coating material containing a glittering material is measured over a predetermined evaluation area.
FIG. 1 shows a measurement system. This measuring system is roughly divided into a measuring unit 10 including a microscopic gloss meter 12 and a control personal computer 14,
Two personal computers 22, 2 for analysis and visualization of measured values
It is composed of two of the analysis units 20 composed of four. The reflected light intensity data measured by the measurement unit 10 is transferred to the analysis personal computer 22 of the analysis unit 20 via the magnetic medium, and the reflected light intensity distribution is evaluated. The result is a visualization personal computer 24
Sent to the final evaluation.

FIG. 2 shows the outline of the optical measurement of the reflected light in a fine area. The reflected light is measured by the micro gloss meter 12. Halogen lamp (light source) in the micro gloss meter 12
This light is applied as incident light 30 to the sample (coating film) 32 from an angle of 30 degrees with respect to the normal line of the film surface. And
The reflected light 34 is narrowed to a spot light having a diameter of 50 μm, received at an angle of 20 ° with respect to the normal line (angle at which specularly reflected light does not enter), and converted into a maximum voltage of 4.999 V by a photoelectric conversion element or the like. The value of the reflected light intensity is 1000 at this time.
The value is doubled. Microscopic gloss meter 12 measurement sensitivity (range)
Must have the same measurement sensitivity in all test samples. Further, it is necessary to perform the measurement at a measurement sensitivity (range) where the reflected light intensity data of the sample coating film showing the maximum reflected light intensity in the test sample is not saturated.

In the measurement, the coating film is 20 mm in the X direction.
After moving, the unevenness of the reflected light in the fine area is measured at intervals of 0.2 mm, and the measurement on one scanning line is completed. When this scanning is completed, it returns to the starting point, moves 0.2 mm in the Y direction, and performs the same scanning as before.
Repeat 100 times in total until moving 0 mm. The total number of scanning lines in the predetermined evaluation area is 101. The predetermined measurement area for evaluating this glitter material type is 20 × 20 = 400 mm ²
Is. FIG. 3 shows 1 of the reflected light intensity data on one scanning line.
As an example, this reflected light intensity is sampled at predetermined intervals and counted in the frequency distribution. Here, the relationship among the fine area, the fine unit area, and the predetermined evaluation area will be described. The fine area is the spot diameter 50 that focuses the reflected light.
μm is the instantaneous measured area on the coated surface (approximately 50 μm
(Diameter circle).

In the micro-gloss meter 12, the analog output data from the photoelectric conversion element is converted into a moving distance on the coated surface by an A / D converter of 12 bits, and A is calculated every 200 μm.
/ D converted and recorded on the magnetic medium. Therefore, the number of reflected light intensity data recorded for one scanning line is 10
It is one. In the measurement of the entire predetermined evaluation area, the interval in the Y direction is also set every 0.2 mm. Therefore, in one measurement, a predetermined evaluation area (X direction × Y direction = 20 mm ×
20mm = 400mm ² ) 0.2mm × 0.2mm (=
Subdivide into a fine unit area of 0.04 mm ² . The number of data corresponding to the fine unit area is 101 in both the X direction and the Y direction, which is 10,201 in total, and generally speaking, the predetermined evaluation area 400 mm ² is about 10,000 fine unit areas (0.04).
It can be said that the evaluation is made by dividing into mm ² ).

The reason why the fine unit area is set to 0.2 mm × 0.2 mm is that there are individual differences in the resolution when a human observes the coated surface (when the distance between the coated plate and human eyes is 25 to 30 cm). This is because it is on the order of 100 μm. In addition, since the X direction and the Y direction are arbitrary on the coated surface, it is necessary to measure and analyze with the same resolution in the X direction and the Y direction. Therefore, the fine unit area is 0.2 mm ×
It was set to 0.2 mm.

The reason why the predetermined evaluation area is 400 mm ² is set. Needless to say, the larger the evaluation area is, the more preferable, but if 1,000 pieces of data are to be collected in each of the X direction and the Y direction, 1,000 × 1, 000 = 1 million pieces of data are required, which is not realistic considering the measurement time and analysis time. On the other hand, if there are 10 pieces of data in each of the X direction and the Y direction, there are only 100 pieces of data, which is not a number that can give a statistically meaningful result. Also,
It is too small as an area from which the entire coated surface can be estimated from the size of the evaluation area (2 mm × 2 mm).

As described above, it is a comprehensive area that the area of the coated surface can be represented appropriately, that the time required for measurement and analysis is practical, and that it is compatible with the resolution of the human eye. Based on the conventional judgment, the fine unit area (0.2 mm × 0.2 m
m), evaluation area (400 mm ² ), number of reflected light intensity data
(About 10,000 pieces) was decided.

Next, preparation of an aluminum coating color sample will be described. First, an intermediate coating layer (gray) on a tin plate (25 ~
30 μm thick) is applied and baked. And a metallic base layer (20 μm thick) containing a luster material (aluminum) thereon,
The transparent clear coating (acrylic resin) (thickness of 30 to 40 μm) for the metallic base was sequentially coated wet-on-wet and baked. In the present embodiment, the glittering materials in the metallic base layer are all the same material type (aluminum pigment).
Is a pigment. As a single bright material, there are three types of coarse aluminum pigments, medium aluminum pigments, and fine aluminum pigments having different particle sizes, which are commercially available for coating outer panels of automobiles. 16μm, D of about 8μm
It has 50 particle sizes (particle size corresponding to the 50% point of the integrated frequency distribution of the particle size distribution curve obtained by measuring the particle size distribution). These aluminum pigments are manufactured using the same mill, and the particle size varies depending on the length of manufacturing time. Further, as a mixed-type glittering material, a mixture of coarse and medium aluminum pigments (rough / medium aluminum pigment) and a mixture of coarse and fine aluminum pigments (rough / fine aluminum pigment) )
And a mixture of medium and fine aluminum pigments (medium /
Fine aluminum pigment). Tables 1 and 2 show the luster material type and luster material concentration (PWC (Pi
gment Weight Concentration) 14%), and a glittering material concentration ratio (PWC of the mixed system is 14% in total). In Table 2, the left / right numerical values of the glitter material concentration are
It represents the weight ratio of the pigments shown on the left / right side.

[0017]

[Table 1]

[Table 2]

Next, the outline of the measurement data analysis method will be described. FIG. 4 shows about 20 μm, about 16 μm, and about 8 μm, respectively.
The measurement results of the reflected light intensity for three kinds of coating colors including a coarse aluminum pigment, a medium aluminum pigment, and a fine aluminum pigment having an average particle diameter of μm are shown. Coatings with coarse aluminum pigments have sharply large peaks, whereas coatings with fine aluminum pigments, in contrast, show nearly random small reflected light behavior. Further, FIG. 5 shows the measurement results of the reflected light intensities for three kinds of coating colors including a mixed coarse / medium aluminum pigment, a coarse / fine aluminum pigment, and a medium / fine aluminum pigment. These figures are a part of the reflected light intensity data for all the samples measured by the measuring unit 10.

Next, the frequency is obtained from the reflected light intensity obtained from the measurement data of the entire predetermined evaluation area. 6 to 11
Are the frequency distributions obtained for coatings containing coarse aluminum pigments, medium aluminum pigments, fine aluminum pigments, coarse / medium aluminum pigments, coarse / fine aluminum pigments and medium / fine aluminum pigments, respectively. Show. In the case of a single sample, the one with a large particle size (those with a large brilliance) (Fig. 6) has a low frequency in the low reflected light intensity region and a "tail" on the high reflected light intensity side
It has a shape with a minus sign. Further, as the particle size becomes smaller (FIG. 8), the frequency of the low reflected light intensity region becomes large, and the frequency distribution shape becomes close to a bell shape. On the other hand, in the mixed system sample mixed with aluminum pigment, the frequency of the low reflected light intensity region is in the middle of the case of being used alone under the influence of mixing, but in the high reflected light intensity region, the behavior in a single system It was found that the behavior close to that was observed.

Next, a function form expressing these actual measurement frequency data was obtained. Typical probability density functions include uniform distribution (square distribution), sine wave distribution, Gaussian distribution, Rayleigh distribution, Maxwell distribution, etc.
It was found that the functional model of the sum of the function forms of (2) and (3) (represented by equation (1)) reproduces the behavior of the actually measured data. 6-
The solid line in each graph of FIG. 11 shows the result obtained by fitting the function model of Expression (1) to frequency data. Here, equation (2)
Is a functional model suitable for approximating the tail portion of the frequency distribution, and the coating color of a single coarse pigment can be mainly expressed by this equation. Further, the formula (3) is the same as the Gaussian distribution and is a functional model suitable for the peak portion, and the coating color of the single-system fine pigment can be mainly expressed by this formula.

## EQU00003 ## N = aR _s exp (-R _s / (2b ² )) (2) Here, N represents frequency and R _s represents reflected light intensity. Further, a and b are parameters, but b is considered to represent dispersion, that is, spread of distribution.

Equation 4] N = Cexp - a ^{_{((R s -D) 2 /}} E) (3) where, C, D, E is a parameter, the parameter representing the mean and variance in the D and E are each a Gaussian distribution Is.

N = aR _s exp (-R _s / (2b ² )) + C exp (-(R _s -D) ² / E) (1)

Equations (4) and (5) are conversion equations assumed for estimating the composition. In the formula (2), a is b ^-2
including. Therefore, the value is converted to the value a ′ that does not include the dispersion term b by the equation (4). Similarly, considering the Gaussian distribution,
Since C ′ includes the reciprocal of the dispersion term E, according to Equation (5),
Convert to a value C that does not include the dispersion term E. That is, a ′ and C ′ are parameters related to the height of the peak of the frequency distribution.

## EQU6 ## a '= ab ² / constant (4)

[Equation 7] C ′ = C (E / 2) ^0.5 * constant (5)

Other functional models were also examined, but no good results were obtained. As a comparative example, FIG. 12 shows the case where the Rayleigh distribution (Equation (6)) is used, and FIG. 13 shows the case where the sum of the Rayleigh distribution and the Gaussian distribution (Equation (7)) is used.

N = fR _s exp (−R _s ² / (2g ² )) (6) Here, g represents a dispersion term, and f is a parameter.

N = fR _s exp (−R _s ² / (2g ² )) + C exp (− (R _s −D) ² / E) (7) where f and g, C, D, and E are It is a parameter obtained by approximate calculation of the frequency distribution. The solid line in these figures represents the obtained function. Obviously, these model functions are not suitable for approximating the actual frequency distribution.

Next, the parameters a and b thus obtained
Consider the behavior of changes such as. 14, FIG. 15 and FIG. 16 show the parameters a for the six samples shown in Tables 1 and 2.
And b, a ′ and b, and a ′ and C ′. In any of the figures, for the single pigment, the parameters change linearly in the order of fine, medium and coarse. Therefore, it is understood that if the parameters of the luster pigment used are measured in advance, the aluminum species can be identified by measuring these amounts. Further, in FIG. 15, for a ′ that is intended to eliminate the dispersion term b,
Considering the data of mixed pigments, coarse / medium, which is a mixed system of relatively similar properties, is located in the middle of both, and in the mixed system of coarse, medium and fine It can be seen that the behave differently. That is, in a fine mixed system, a '(height of frequency distribution) does not change much by mixing coarse, medium and fine, and the dispersion term b of the distribution, that is, the spread is reduced.

Further, in FIG. 16, the result is obtained that a'and C'are inversely proportional. For three types of coarse aluminum pigments, medium aluminum pigments, and fine aluminum pigments, the larger the average particle size, the larger a '(term indicating the height of the function indicating the tail portion) and C' (representing the peak portion). The term indicating the height of the function) becomes smaller. This means that the contribution of the equation (2) representing the tail portion is larger as the average particle size is larger, which is a reasonable result. For mixed luster pigments, the results for the coarse / medium aluminum pigments are located between the coarse and medium aluminum pigments, and the results for the medium / fine aluminum pigments are the medium and fine aluminum pigments. Located between and with reasonable results. In addition, the result of coarse / fine aluminum pigment is
Although it is located close to the coarse aluminum pigment, it also shows that the height of the function of the tail part is almost dominated by the coarse pigment in the coarse / fine mixed system, which is in good agreement with the empirical results. There is.

From the above results, the behavior of the frequency distribution should be expressed by the function model (1) which is the sum of the function (2) suitable for expressing the tail part and the function (3) suitable for expressing the peak part. It was found that it is possible to express the positional relationship between a single system and a mixed system. That is, it is estimated that the frequency distribution of the mixed glitter material can be expressed as a linear sum of the frequency distribution of the single glitter material. Then, the approximation by the formula (1) and the formula
It can be seen that the transformations according to (4) and (5) can be used to estimate the blending of multiple pigments.

[0026]

It has been found that the behavior of the frequency distribution of reflected light intensity can be expressed by an appropriate functional model. As a result, it became possible to characterize the coating color containing the bright material, and it became possible to identify the bright material type of the same bright material (for example, aluminum) and estimate the mixture thereof.

[Brief description of drawings]

FIG. 1 is a block diagram of a measuring device.

FIG. 2 is a diagram showing an outline of reflected light intensity measurement using a microscopic gloss meter.

FIG. 3 is a graph showing an example of reflected light intensity data on one scanning line measured by a micro gloss meter.

FIG. 4 is a graph of an example of reflected light intensity data of three test samples of a single system.

FIG. 5 is a graph of an example of reflected light intensity data of three types of test samples of a mixed system.

FIG. 6 is a graph of frequency distribution of reflected light intensity of a coating film containing a rough aluminum pigment.

FIG. 7 is a graph of frequency distribution of reflected light intensity of a coating film containing a medium-sized aluminum pigment.

FIG. 8 is a graph of frequency distribution of reflected light intensity of a coating film containing a fine aluminum pigment.

FIG. 9 is a graph of frequency distribution of reflected light intensity of a coating film containing a rough / medium-grained aluminum pigment.

FIG. 10 is a graph of frequency distribution of reflected light intensity of a coating film containing a coarse / fine aluminum pigment.

FIG. 11 is a graph of frequency distribution of reflected light intensity of a coating film containing a medium / fine aluminum pigment.

FIG. 12 is a graph when Rayleigh distribution is used as a model function of frequency distribution.

FIG. 13 is a graph when Rayleigh distribution and Gaussian distribution are used as a model function of frequency distribution.

FIG. 14 is a graph showing the relationship between parameters a and b in 6 samples.

FIG. 15 is a graph showing the relationship between parameters a ′ and b in 6 samples.

FIG. 16 is a graph showing a relationship between parameters a ′ and C ′ in 6 samples.

[Explanation of symbols]

12 ... Micro gloss meter, 14 ... PC, 30 ... Incident light,
32 ... Coating film, 34 ... Reflected light.

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A 8-110301 (JP, A) JP-A 6-117934 (JP, A) JP-A 2-156140 (JP, A) JP-A 5- 288690 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 G01N 21/84-21/958 JISST file (JOIS ) Practical file (PATOLIS) Patent file (PATOLIS)

Claims (4)

(57) [Claims] 1. A glitter material species of a coating film containing a glitter material, and the same.
A method for estimating the mixing, light is irradiated to the coating film surface from a light source, a predetermined evaluation area intensity of the reflected light from the fine area of the light-receiving to the coating film surface from the angle of specular reflection light does not enter The entire distribution is measured, and the frequency distribution is obtained from the reflected light intensity data obtained from this measurement. Next, this frequency distribution is calculated by the following function N = aR _s exp (-R _s / (2b ² ). ) + Cex
p (-(R _s -D) ² / E) (where N represents the frequency at the reflected light intensity R _s , a,
b, C, D and E are parameters obtained by calculation), and the roughness of the bright material in the coating film is estimated from the values of the obtained parameters. A method for estimating the type of bright material in a coating film and its composition. 2. The method according to claim 1, wherein the measurement of the reflected light intensity is performed by using a micro gloss meter. 3. The method according to claim 1, wherein the particles
Frequency distribution of single-type bright materials with different diameters and frequency of mixed-type bright materials
The positional relationship with the degree distribution is determined by the parameters obtained from the above function.
Brightness by optical measurement characterized by data evaluation
A method for estimating the luster material type of a coating film containing a material and its composition. 4. A glitter material species of a coating film containing a glitter material and the same.
A method of estimating the composition , in which the light source irradiates the coating film surface with light and specular reflection light does not enter.
Light received from an angle and reflected from a fine area of the coating film surface
Of the reflected light intensity data obtained from this measurement.
A distribution is obtained, and then the frequency distribution is calculated by the following function N = aR _s exp (−R _s / (2b ² )) + C exp (− (R
_s- D) ² / E) (where N represents the frequency at the reflected light intensity R _s , a,
b, C, D and E are parameters obtained by calculation
Approximated by some), then the 'a represented by = ab ² / constant' following formula a, by a 'C represented by ^{= C (E / 2) 0.5} * constants' following formula C , The variance terms b and E are not included
Estimate the peak height of the intensity distribution and mix multiple luster pigments
Of bright materials by optical measurement characterized by estimating
A method for estimating the type of bright material in a coated film and its composition.