Method for evaluating degree of contamination

Abstract

A method for evaluating the degree of contamination in which an evaluation device (100) evaluates the degree of contamination of a water-repellent coating film (P), the method comprising acquiring first measurement data obtained by measuring the unevenness of the surface of the coating film, acquiring second measurement data obtained by measuring the unevenness of the surface of the coating film after the water-repellent coating film (P) is exposed to a dust environment, calculating the difference between the first measurement data and the second measurement data, and evaluating the degree of contamination of the water-repellent coating film (P) on the basis of the difference.

Description

Contamination level evaluation method

[0001] The present disclosure relates to an evaluation method for evaluating the degree of contamination of a water-repellent coating film.

[0002] For articles used outdoors, a water-repellent coating film is applied to the surface of the article to ensure water repellency. When an article coated with a water-repellent coating film is exposed to the external environment for a long period of time, the surface becomes contaminated and the water repellency deteriorates. For this reason, it is desirable to evaluate the susceptibility of the water-repellent coating film to soiling (hereinafter referred to as "degree of soiling"). That is, a water-repellent coating film with a high degree of soiling (easily soiled) is likely to be easily soiled by dust and other particles in an outdoor environment, and therefore its water repellency is likely to deteriorate. On the other hand, a water-repellent coating film with a low degree of soiling (less likely to be soiled) is likely to be less susceptible to soiling and therefore less likely to deteriorate in water repellency. Evaluating the degree of soiling leads to an evaluation of the sustainability of the water repellency of the article over time.

[0003] Non-Patent Document 1 discloses that a test plate is exposed outdoors, and after a predetermined period of time, the gloss retention, color difference, and brightness difference of the test plate are measured to evaluate the degree of contamination of the test plate. The greater the change in gloss retention, color difference, and brightness difference between before and after the test plate is exposed outdoors, the higher the degree of contamination is evaluated. Furthermore, Non-Patent Document 2 discloses a method for evaluating the surface roughness of an object.

[0004] Research on coating contamination evaluation methods, [Retrieved September 5, 2024], Internet <URL: https: / / www.jstage.jst.go.jp / article / finex / 2014 / 0 / 2014_20 / _pdf / -char / ja> Surface roughness measurement - parameters, [Retrieved September 5, 2024], Internet <URL: https: / / www.olympus-ims.com / ja / metrology / surface-roughness-measurement-portal / parameters / #!cms[focus]=024>

[0005] However, the method disclosed in Non-Patent Document 1 has the problem that the evaluation result of the contamination level varies depending on the color of the coating film applied to the material. For example, if the water-repellent coating film to be measured for contamination level is white and black carbon black is attached to its surface, the contamination level of the water-repellent coating film can be evaluated using the above-mentioned indicators such as gloss retention, color difference, and brightness difference. However, if the water-repellent coating film is black and carbon black is attached to its surface, it is difficult to compare the gloss retention, color difference, and brightness difference.

[0006] Furthermore, while Non-Patent Document 2 discloses various parameters for evaluating the surface roughness of a material, it does not disclose any parameters for evaluating the degree of contamination of a water-repellent coating.

[0007] This disclosure has been made in view of the above circumstances, and its purpose is to provide a contamination evaluation method that can evaluate the degree of contamination of a coating film with high accuracy.

[0008] A contamination evaluation method according to one embodiment of the present disclosure is a contamination evaluation method in which an evaluation device evaluates the contamination level of a coating film, obtains first measurement data that measures the unevenness of the coating film surface, obtains second measurement data that measures the unevenness of the coating film surface after exposing the coating film to a dusty environment, calculates the difference between the first measurement data and the second measurement data, and evaluates the contamination level of the coating film based on the difference.

[0009] According to this disclosure, it becomes possible to evaluate the degree of contamination of a coating with high accuracy.

[0010] FIG. 1A is an explanatory diagram showing a state in which dust has been sprinkled on a material coated with a white water-repellent coating film. FIG. 1B is an explanatory diagram showing a state in which dust has been sprinkled on a material coated with a black water-repellent coating film. FIG. 2 is a block diagram showing the configuration of an evaluation device in which a contamination level evaluation method according to an embodiment is employed. FIG. 3A is an explanatory diagram according to a first embodiment showing a state in which dust has been sprinkled on a water-repellent coating film having an uneven surface, causing dirt to adhere to convex portions of the surface. FIG. 3B is an explanatory diagram according to the first embodiment showing a state in which dust has been sprinkled on a water-repellent coating film having an uneven surface, causing dirt to adhere to concave portions of the surface. FIG. 4 is a flowchart showing the processing steps of the contamination level evaluation method according to the first embodiment. FIG. 5 is an explanatory diagram according to a second embodiment showing a state in which dust has been sprinkled on a water-repellent coating film having a flat surface, causing dirt to adhere to the surface. FIG. 6 is a flowchart showing the processing steps of the contamination level evaluation method according to the second embodiment. FIG. 7 is an explanatory diagram showing a state in which dirt adheres to recesses on a water-repellent coating film having an uneven surface by sprinkling dust on the surface according to a modified example of the second embodiment. FIG. 8 is a flowchart showing the processing steps of a contamination level evaluation method according to a modified example of the second embodiment. FIG. 9A is an explanatory diagram showing a state in which dirt adheres to protrusions on a water-repellent coating film having an uneven surface by sprinkling dust on the surface according to a third embodiment. FIG. 9B is an explanatory diagram showing a state in which dirt adheres to recesses on the surface according to a third embodiment by sprinkling dust on the water-repellent coating film having an uneven surface. FIG. 9C is an explanatory diagram showing a state in which dirt adheres to both recesses and protrusions on the surface according to the third embodiment by sprinkling dust on the water-repellent coating film having an uneven surface. FIG. 10 is a flowchart showing the processing steps of a contamination level evaluation method according to the third embodiment. Fig. 11A is an explanatory diagram showing a state in which dirt adheres to convex portions of a water-repellent coating film having an uneven surface by sprinkling dust thereon, Fig. 11B is an explanatory diagram showing a state in which dirt adheres to concave portions of a water-repellent coating film having an uneven surface by sprinkling dust thereon, and Fig. 11C is an explanatory diagram showing a state in which dirt adheres to both concave and convex portions of a water-repellent coating film having an uneven surface by sprinkling dust thereon, according to the fourth embodiment.Fig. 12 is a flowchart showing the processing procedure of the contamination level evaluation method according to the fourth embodiment, and Fig. 13 is a block diagram showing the hardware configuration of this embodiment.

[0011] [Description of the First Embodiment] The embodiments will be described below with reference to the drawings. Figures 1A and 1B are explanatory diagrams showing the state of a material coated with a water-repellent coating before and after sprinkling it with black dust (for example, carbon black). Figure 1A shows a material with a white water-repellent coating on its surface. Figure 1B shows the case where a material with a black water-repellent coating on its surface is used. To simulate the state of each material being exposed to the outdoors for a long period of time, dust is intentionally sprinkled on the surface of the material. The water-repellent coating is just one example of a coating.

[0012] Figure 1A(a) shows a material coated with a white water-repellent coating film P1, and Figure 1A(b) shows the state after dust has been sprinkled on the surface of the water-repellent coating film P1. Figure 1B(a) shows a material coated with a black water-repellent coating film P1, and Figure 1B(b) shows the state after dust has been sprinkled on the surface of the water-repellent coating film P1.

[0013] As shown in Figure 1A, dust is sprinkled on the surface of a white water-repellent coating P1, causing dirt d1 to form on the surface of the coating P1. By measuring the color difference and brightness difference of the surface with a colorimeter, the results show that the color difference before and after the dust-induced dirt adheres is "+0.5" and the brightness difference is "+1.0". Furthermore, by imaging the surface with a camera and processing the image, the rate of change of the dirt area is "+1.5 (% / mm²)". ２ The result is obtained as follows: Based on this result, the susceptibility of the water-repellent coating P1 to dirt (degree of contamination) can be evaluated.

[0014] On the other hand, as shown in FIG. 1B , even when dust is sprinkled on the surface of a black water-repellent coating film P2, stains are generated on the surface of the water-repellent coating film P2. However, even when black dust adheres to the surface of the black water-repellent coating film P2, it is difficult to calculate the change in the stain area from an image of the surface. Furthermore, it is difficult to measure the color difference and brightness difference using a colorimeter. Furthermore, when the color and gloss of the surface of the water-repellent coating film P2 are similar to those of the stain, these differences cannot be distinguished, making it difficult to evaluate the stain adhered to the surface of the water-repellent coating film P2. In other words, it is difficult to evaluate the degree of contamination of the surface of the water-repellent coating film P2 based on images captured by a camera and measurement data from a colorimeter. In this embodiment, the degree of contamination of the water-repellent coating film when exposed to dust is evaluated by measuring the change in surface roughness of the water-repellent coating film. This is described in detail below.

[0015] Fig. 2 is a block diagram showing the configuration of an evaluation device 100 to which the contamination level evaluation method according to the first embodiment is applied. As shown in Fig. 2, the evaluation device 100 includes a transmitter / receiver unit 1, a calculation unit 2, an evaluation unit 3, and an output unit 4. The evaluation device 100 evaluates the contamination level of a water-repellent coating film P (coating film).

[0016] The transmitting / receiving unit 1 irradiates a laser beam onto the surface of a sample 10 coated with a water-repellent coating film P, which is the target for measuring the degree of contamination. The transmitting / receiving unit 1 receives the laser beam reflected from the surface of the water-repellent coating film P. Note that, although the present embodiment shows an example in which laser beam is irradiated to measure the unevenness of the surface of the water-repellent coating film P, a wave other than laser beam may also be irradiated. Furthermore, the target for measuring the degree of contamination is not limited to the water-repellent coating film P, and laser beam may also be irradiated onto the surface of a material other than the water-repellent coating film P.

[0017] The calculation unit 2 measures the distribution of irregularities occurring on the surface of the water-repellent coating film P based on the laser light received by the transmitting / receiving unit 1. The distribution of irregularities refers to the distribution of protruding and recessed distances relative to a set reference height. Other irregularity distribution data that can be calculated include the "developed interface area ratio Sdr," "arithmetic mean height Sa," "skewness Ssk," and "kurtosis Sku," which are described in the aforementioned Non-Patent Document 2.

[0018] The calculation unit 2 creates a graph showing the relationship between height and frequency distribution based on the above-mentioned unevenness distribution data. Specifically, the height / frequency distribution graph is generated based on the unevenness distribution when no dirt is attached to the surface of the water-repellent coating film P formed on the sample 10. The height / frequency distribution graph is also generated based on the unevenness distribution after dirt has attached to the surface of the water-repellent coating film P.

[0019] FIG. 3A(a) is an explanatory diagram showing the state of the surface 11 of the water-repellent coating film P when no dirt is attached, and FIG. 3A(b) is an explanatory diagram schematically showing the state in which dirt 12 caused by dust (e.g., carbon black) is attached to the convex portions 11a of the surface 11. As shown in FIG. 3A(a), the surface 11 of the water-repellent coating film P has regularly-spaced convex portions 11a and concave portions 11b. Therefore, the height / frequency distribution graph shows peaks in the frequency distribution at two heights (concave portions, convex portions), as shown by curve s1 in FIG. 3A(c). Curve s1 is an example of first measurement data obtained by measuring the unevenness of the coating film surface. Curve s1 is an example of a first unevenness frequency distribution of the coating film surface before the water-repellent coating film P was exposed to a dusty environment.

[0020] Furthermore, as shown in FIG. 3A(b), when dirt 12 adheres to the convex portions 11a on the surface 11 of the water-repellent coating film P, the height / frequency distribution graph shows a graph in which the right-hand peak (the peak due to the convex portion) of the two peaks in the frequency distribution is shifted to the right compared to curve s1, as shown by curve s2 in FIG. 3A(d). Curve s2 is an example of second measurement data measuring the uneven state of the coating film surface after exposing the water-repellent coating film P to a dusty environment. Curve s2 is an example of a second unevenness frequency distribution of the coating film surface after exposing the water-repellent coating film P to a dusty environment. The calculation unit 2 generates the graphs (curves s1 and s2) shown in FIGS. 3A(c) and 3A(d).

[0021] Fig. 3B(a) is an explanatory diagram showing the state of the surface 11 of the water-repellent coating film P when no dirt is attached, and Fig. 3B(b) is an explanatory diagram showing a state in which dust dirt 12 is attached to the recesses 11b of the surface 11. Fig. 3B(a) is similar to Fig. 3A(a) described above, and shows that the surface 11 of the water-repellent coating film P has regular convex portions 11a and concave portions 11b. Therefore, the height / frequency distribution graph shows peaks in the frequency distribution at two heights, as shown by curve s1 in Fig. 3B(c).

[0022] Furthermore, as shown in FIG. 3B(b), when dirt 12 adheres to a recess 11b on the surface 11 of the water-repellent coating P, the left-hand peak (the peak due to the recess) of the two peaks in the frequency distribution of the height / frequency distribution is shifted to the right compared to curve s1, as shown by curve s3 in FIG. 3B(d). Curve s3 is an example of second measurement data measuring the uneven state of the coating surface after exposing the water-repellent coating P to a dusty environment. Curve s3 is an example of a second unevenness frequency distribution of the coating surface after exposing the water-repellent coating P to a dusty environment. The calculation unit 2 generates the graphs (curves s1 and s3) shown in FIGS. 3B(c) and (d).

[0023] The evaluation unit 3 evaluates the susceptibility of the water-repellent coating P applied to the surface of the water-repellent coating P (level of contamination) based on the graph generated by the calculation unit 2. Specifically, when contamination 12 adheres to the convex portions 11a on the surface 11 of the water-repellent coating P as shown in FIG. 3A(b), the graph showing the height / frequency distribution relationship becomes a curve s2, in which the peak due to the convex portion is shifted to the right, as shown in FIG. 3A(d). The evaluation unit 3 evaluates the level of contamination based on the amount of this shift (the amount of change in the peaks between curves s1 and s2). Specifically, the larger the shift amount, the more susceptible the convex portions 11a are to contamination (the higher the level of contamination). Alternatively, the level of contamination may be evaluated based on the area of ​​the region indicated by symbol D1 in FIG. 3A(d).

[0024] Furthermore, as shown in FIG. 3B(b), when dirt 12 adheres to the recesses 11b on the surface 11 of the water-repellent coating P, the frequency distribution shows a curve s3 in which the peak due to the recesses is shifted to the right, as shown in FIG. 3B(d). The evaluation unit 3 evaluates the degree of contamination based on the amount of this shift (the amount of change in the peaks of curves s1 and s3). Specifically, the greater the amount of shift, the more easily dirt adheres to the recesses 11b (the higher the degree of contamination). The degree of contamination may also be evaluated based on the area of ​​the region indicated by symbol D2 in FIG. 3B(d).

[0025] Furthermore, when contamination 12 adheres to both the convex portions 11a and the concave portions 11b of the surface 11, both of the two peaks of the curve s1 shown in Figures 3A(c) and 3B(c) shift to the right. The evaluation unit 3 evaluates the degree of contamination based on the amount of shift of both peaks, i.e., the amount of change in the peaks of the curves s1 and s2, and the amount of change in the peaks of the curves s1 and s3. The evaluation unit 3 calculates the difference between the first measurement data (curve s1) and the second measurement data (curves s2 and s3), and evaluates the degree of contamination of the water-repellent coating film P based on this difference. That is, the evaluation unit 3 evaluates the degree of contamination of the water-repellent coating film P based on the difference between the first asperity frequency distribution and the second asperity frequency distribution.

[0026] 2, the output unit 4 outputs the results of the evaluation by the evaluation unit 3 to the outside. For example, the results of the evaluation can be displayed on a display or the like.

[0027] Next, the processing steps of the contamination level evaluation method according to the first embodiment will be described with reference to the flowchart shown in Fig. 4. First, in step S11 of Fig. 4, the transmitter / receiver 1 irradiates a laser beam onto the surface of the water-repellent coating film P before contamination adheres thereto, i.e., before dust (e.g., carbon black) is sprinkled on the surface of the water-repellent coating film P. The transmitter / receiver 1 receives the reflected laser beam. The calculator 2 calculates the frequency distribution of the height of the surface of the water-repellent coating film P based on the reflected laser beam. As a result, for example, the curve s1 shown in Fig. 3A(c) and Fig. 3B(c) can be obtained.

[0028] In step S12, the operator sprinkles dust on the surface of the water-repellent coating film P of the sample 10. Carbon black, for example, can be used as the dust.

[0029] In step S13, the transmitter / receiver 1 irradiates the surface of the water-repellent coating P after dusting with laser light, and the calculation unit 2 calculates the frequency distribution of the heights. As a result, for example, the curve s2 shown in Fig. 3A(d) or the curve s3 shown in Fig. 3B(d) is obtained.

[0030] In step S14, the calculation unit 2 calculates the peak shift of the height / frequency distribution curves (s1 to s3).

[0031] In step S15, the evaluation unit 3 evaluates the degree of contamination of the water-repellent coating P applied to the sample 10 based on the peak shift. Specifically, the evaluation unit 3 evaluates that the greater the peak shift, the higher the degree of contamination. For example, the peak shift amount is shown numerically, and the degree of contamination is quantified by this value. Furthermore, based on which of the two peaks has shifted, it evaluates whether the dirt 12 is attached to the convex portion 11a or the concave portion 11b of the surface 11 of the water-repellent coating P. The output unit 4 informs the operator of the degree of contamination of the water-repellent coating P and the location of the dirt 12 attachment by displaying the evaluation results from the evaluation unit 3 on, for example, a display (not shown).

[0032] As described above, the contamination level evaluation method according to this embodiment is a contamination level evaluation method in which an evaluation device 100 evaluates the contamination level of a water-repellent coating film P, and acquires first measurement data measuring the unevenness of the surface of the coating film, acquires second measurement data measuring the unevenness of the surface of the coating film P after exposing the water-repellent coating film P to a dusty environment, calculates the difference between the first measurement data and the second measurement data, and evaluates the contamination level of the water-repellent coating film P based on the difference.

[0033] In this embodiment, the degree of contamination of the water-repellent coating P applied to the sample 10 is evaluated by measuring the surface irregularities of the coating P. Compared to conventional methods employing image analysis, this method allows for highly accurate evaluation of the degree of contamination. Furthermore, by quantifying the peak shift amount, the degree of contamination can be presented quantitatively. Moreover, it becomes possible to evaluate the degree of contamination regardless of the color of the material.

[0034] [Description of the Second Embodiment] Next, the second embodiment will be described. The contamination level evaluation method according to the second embodiment is carried out by the evaluation device 100 shown in Figure 2. In the second embodiment, the calculation unit 2 shown in Figure 2 acquires reflected light received by the transmitting / receiving unit 1. Based on this reflected light, the calculation unit 2 measures the amount of change (hereinafter abbreviated as "area ratio Sdr") of the unfolded interface area ratio Sdr (hereinafter abbreviated as "area ratio Sdr") of the surface of the water-repellent coating P before and after contamination (this is referred to as "difference ΔSdr"). Based on this difference ΔSdr, the evaluation unit 3 evaluates the contamination level of the water-repellent coating P. A detailed explanation follows below.

[0035] 5 is an explanatory diagram showing how dust is sprinkled onto a surface 21 of a planar water-repellent coating film P to cause dirt 22 to adhere to the surface 21. Fig. 5(a) shows the state before dust is sprinkled, (b) shows the state when only a small amount of dirt 22 has adhered to the surface 21, and (c) shows the state when a large amount of dirt 22 has adhered to the surface.

[0036] By irradiating the surface 21 of the water-repellent coating P with laser light, the area ratio Sdr1 of the surface 21 before dust is sprinkled on it is measured, and then the area ratio Sdr2 of the surface 21 after dust is sprinkled on it is measured, and the difference between these two, ΔSdr (= Sdr2 - Sdr1), is calculated. The larger the difference ΔSdr, the higher the degree of contamination is considered to be.

[0037] Area ratio Sdr1 is an example of first measurement data measuring the surface roughness of the coating film. The first measurement data includes the area ratio Sdr1 (first unfolded interface area ratio) of the coating film surface before the water-repellent coating film P is exposed to a dusty environment. Area ratio Sdr2 is an example of second measurement data measuring the surface roughness of the coating film after the water-repellent coating film P is exposed to a dusty environment. The second measurement data includes the area ratio Sdr2 (second unfolded interface area ratio) of the coating film surface after the water-repellent coating film P is exposed to a dusty environment. The calculation unit 2 calculates the difference ΔSdr (first difference) between the area ratio Sdr1 (first unfolded interface area ratio) and the area ratio Sdr2 (second unfolded interface area ratio). The evaluation unit 3 evaluates the degree of contamination of the water-repellent coating film P based on the first difference.

[0038] As is well known, the area ratio Sdr (developed interface area ratio) is the ratio between the surface area and the area A obtained by projecting the surface area onto the X-Y plane, and can be expressed by the following formula (1): The denser and more rugged the surface shape is, the larger the area ratio Sdr becomes.

[0039]

[0040] When dust is sprinkled onto a planar surface 21 shown in Figure 5(a), dirt adheres to the surface 21. In the case of a water-repellent coating film P with a low degree of contamination, the amount of dirt 22 adhering to the surface 21 is small, as shown in Figure 5(b), whereas in the case of a water-repellent coating film P with a high degree of contamination, the amount of dirt 22 adhering is large, as shown in Figure 5(c). Therefore, the degree of contamination of the surface 21 can be evaluated based on the area ratio Sdr of the surface 21 before and after sprinkling the dust.

[0041] Specifically, the area ratio Sdr1 is measured before dusting, and the area ratio Sdr2 is measured after dusting. The difference ΔSdr between the two (= Sdr2 - Sdr1) is calculated, and the greater this difference ΔSdr is, the higher the level of contamination is evaluated.

[0042] The processing procedure of the contamination level evaluation method according to the second embodiment will be described below with reference to the flowchart shown in Fig. 6. First, in step S21 in Fig. 6, the transmitter / receiver 1 irradiates a laser beam onto the surface of the water-repellent coating film P applied to the sample 10 before dust (e.g., carbon black) is sprinkled on the sample 10, and receives the reflected light. The calculator 2 calculates the surface area ratio Sdr1 of the water-repellent coating film P based on the reflected light.

[0043] In step S22, the operator sprinkles dust on the surface of the water-repellent coating film P. Carbon black, for example, can be used as the dust.

[0044] In step S23, the transmitter / receiver 1 irradiates the surface of the water-repellent coating P after the dust has been sprinkled with a laser beam and receives the reflected light. Based on the reflected light, the calculation unit 2 calculates the surface area ratio Sdr2 of the water-repellent coating P. Since the dust sprinkles cause dirt 22 to adhere to the surface of the water-repellent coating P, the area ratio increases.

[0045] In step S24, the calculation unit 2 calculates the difference ΔSdr (=Sdr2−Sdr1) between the area ratios before and after the dust adhesion.

[0046] In step S25, the evaluation unit 3 evaluates the degree of contamination of the water-repellent coating P applied to the sample 10 based on the difference ΔSdr. Specifically, the evaluation unit 3 evaluates that the greater the difference ΔSdr, the higher the degree of contamination. The output unit 4 notifies the operator of the degree of contamination of the water-repellent coating P by displaying the evaluation result from the evaluation unit 3 on, for example, a display (not shown).

[0047] In this way, in the contamination evaluation method according to the second embodiment, dust is sprinkled onto a water-repellent coating film P having a flat surface, and the contamination level of the water-repellent coating film P is evaluated based on the change in the developed interface area ratio Sdr (difference ΔSdr), making it possible to evaluate the contamination level of the water-repellent coating film P with simple operations.

[0048] [Description of Modified Examples of the Second Embodiment] Next, a modified example of the second embodiment described above will be explained. In the second embodiment described above, an example was described in which the surface of the water-repellent coating P applied to the sample 10 was flat. In the modified example, the degree of contamination of the water-repellent coating P having an uneven surface is evaluated using the area ratio Sdr described above.

[0049] Figure 7 is an explanatory diagram showing an example in which dust is sprinkled onto a water-repellent coating film P, on which convex portions 23a and concave portions 23b are regularly formed on the surface 23, causing dirt 22 to adhere to the surface 23. Figure 7(a) schematically shows the state before sprinkling dust, and Figure 7(b) schematically shows the state after sprinkling dust. As dirt 22 from the dust adheres to the concave portions 23b of the surface 23, the area ratio Sdr decreases.

[0050] Therefore, the area ratio Sdr1 of the surface 21 before dusting is measured, and the area ratio Sdr2 of the surface 21 after dusting is measured, and the difference ΔSdr between these (= Sdr2 - Sdr1) is calculated. The larger the absolute value of the difference ΔSdr, the higher the degree of contamination is evaluated.

[0051] The processing procedure of the contamination level evaluation method according to the modified example will be described below with reference to the flowchart shown in Fig. 8. First, in step S31 in Fig. 8, the transmitter / receiver 1 irradiates a laser beam onto the surface of the water-repellent coating film P applied to the sample 10 before dust (e.g., carbon black) is sprinkled on the sample 10, and receives the reflected light. The calculator 2 calculates the surface area ratio Sdr1 of the water-repellent coating film P based on the reflected light.

[0052] In step S32, the operator sprinkles dust on the surface of the water-repellent coating film P. Carbon black, for example, can be used as the dust.

[0053] In step S33, the transmitter / receiver 1 irradiates the surface of the water-repellent coating P after the dust has been sprinkled with laser light and receives the reflected light. The calculation unit 2 calculates the surface area ratio Sdr2 of the water-repellent coating P based on the reflected light.

[0054] In step S34, the calculation unit 2 calculates the difference ΔSdr (=Sdr2-Sdr1) between the area ratios before and after the dust adhesion. As shown in Figure 7B, when the dirt 22 adheres to the recesses 23b of the surface 23, the area ratio Sdr2 decreases relative to Sdr1, so the difference ΔSdr becomes a negative value.

[0055] In step S35, the evaluation unit 3 evaluates the degree of contamination of the water-repellent coating film P applied to the sample 10 based on the absolute value of the difference ΔSdr. Specifically, the evaluation unit 3 evaluates that the greater the absolute value of the difference ΔSdr, the higher the degree of contamination. The output unit 4 notifies the operator of the degree of contamination of the sample 10 by displaying the evaluation result by the evaluation unit 3, for example, on a display (not shown).

[0056] In this way, in the contamination evaluation method according to the modified example of the second embodiment, dust is sprinkled onto a water-repellent coating film P having an uneven surface, and the contamination level of the water-repellent coating film P is evaluated based on the absolute value of the change in the developed interface area ratio Sdr, making it possible to evaluate the contamination level of the water-repellent coating film P with simple operations.

[0057] [Description of the Third Embodiment] Next, the third embodiment will be described. The contamination level evaluation method according to the third embodiment is carried out by the evaluation device 100 shown in Figure 2. In the third embodiment, the calculation unit 2 shown in Figure 2 acquires reflected light received by the transmitting / receiving unit 1. Similar to the second embodiment described above, the calculation unit 2 measures the amount of change (difference ΔSdr) of the surface area ratio Sdr (developed interface area ratio) of the water-repellent coating P before and after contamination based on this reflected light. Based on this difference ΔSdr, the evaluation unit 3 evaluates which parts of the water-repellent coating P, which has an uneven surface shape, are more prone to dirt adhesion. A detailed explanation follows below.

[0058] Figures 9A, 9B, and 9C are explanatory diagrams showing the state when dust is sprinkled on a water-repellent coating film P having an uneven surface 31, causing dirt 32 to adhere to the surface 31. Figure 9A shows the state where dirt 32 adheres to the convex portion 31a of the surface 31, with Figure 9A(a) showing before dust is sprinkled and Figure 9A(b) showing after dust is sprinkled. Figure 9B shows the state where dirt 32 adheres to the concave portion 31b of the surface 31, with Figure 9B(a) showing before dust is sprinkled and Figure 9B(b) showing after dust is sprinkled. Figure 9C shows the state where dirt 32 adheres to both the convex portion 31a and the concave portion 31b of the surface 31, with Figure 9C(a) showing before dust is sprinkled and Figure 9C(b) showing after dust is sprinkled.

[0059] As shown in Figure 9A, when dust contaminants 32 adhere to the protrusions 31a, the difference in surface area ratio ΔSdr of the surface 31 is a positive value (for example, +0.155). As shown in Figure 9B, when dust contaminants 32 adhere to the recesses 31b, the difference in surface area ratio ΔSdr of the surface 31 is a negative value (for example, -0.155). As shown in Figure 9C, when dust contaminants 32 adhere to both the protrusions 31a and the recesses 31b, the difference in surface area ratio ΔSdr of the surface 31 is approximately zero. In other words, when the difference ΔSdr is approximately zero, it means that contaminants 32 adhere to both the protrusions 31a and the recesses 31b, or that very little contaminants 32 adhere to them. That is, the areas to which contaminants 32 adhere can be evaluated based on the difference in surface area ratio ΔSdr.

[0060] The processing procedure of the contamination level evaluation method according to the third embodiment will be described below with reference to the flowchart shown in Fig. 10. First, in step S41 in Fig. 10, the transmitter / receiver 1 irradiates a laser beam onto the surface of the water-repellent coating film P applied to the sample 10 before dust (e.g., carbon black) is sprinkled on the sample 10, and receives the reflected light. The calculator 2 calculates the surface area ratio Sdr1 of the water-repellent coating film P based on the reflected light.

[0061] In step S42, the operator sprinkles dust on the surface of the water-repellent coating film P. Carbon black, for example, can be used as the dust.

[0062] In step S43, the transmitter / receiver 1 irradiates the surface of the water-repellent coating P after the dust has been sprinkled with laser light and receives the reflected light. The calculation unit 2 calculates the surface area ratio Sdr2 of the water-repellent coating P based on the reflected light.

[0063] In step S44, the calculation unit 2 calculates the difference ΔSdr (=Sdr2−Sdr1) between the area ratios before and after the dust adhesion.

[0064] In step S45, the evaluation unit 3 determines whether the difference ΔSdr is smaller than a predetermined threshold value "-SdrX." If "ΔSdr<-SdrX" holds (S45; YES), the process proceeds to step S46; if not (S45; NO), the process proceeds to step S47.

[0065] In step S46, the evaluation unit 3 evaluates that dirt 32 is attached to the convex portions 31a on the surface 31 of the water-repellent coating film P, as shown in Figure 9A. Thereafter, the output unit 4 outputs this evaluation result to the outside, and this process ends.

[0066] In step S47, the evaluation unit 3 determines whether the difference ΔSdr is greater than a predetermined threshold value “SdrX.” If “ΔSdr>SdrX” holds (S47; YES), the process proceeds to step S48; otherwise (S47; NO), the process proceeds to step S49.

[0067] In step S48, the evaluation unit 3 evaluates that dirt 32 is adhering to the recesses 31b on the surface 31 of the water-repellent coating P, as shown in Figure 9B. Subsequently, the output unit 4 outputs this evaluation result to the outside, and the process ends.

[0068] In step S49, the evaluation unit 3 determines that the difference ΔSdr is within the range of "-SdrX≦ΔSdr≦SdrX".

[0069] In step S50, the evaluation unit 3 evaluates that dirt 32 is attached to both the convex portion 31a and the concave portion 31b on the surface 31 of the water-repellent coating P, as shown in Figure 9C. Alternatively, it evaluates that there is no dirt. After that, the output unit 4 outputs this evaluation result to the outside and ends this process.

[0070] In this way, the contamination level evaluation method according to the third embodiment makes it possible to evaluate the portions of the water-repellent coating film P having an uneven surface 31 to which dirt 32 adheres, based on the magnitude of the difference ΔSdr in the developed interface area ratio and whether it is a positive or negative numerical value. Specifically, it is possible to evaluate to which portions of the surface 31 dirt 32 is likely to adhere: the convex portions 31 a, the concave portions 31 b, or both the convex portions 31 a and the concave portions 31 b.

[0071] [Description of Fourth Embodiment] Next, a fourth embodiment will be described. The contamination level evaluation method according to the fourth embodiment is performed by an evaluation device 100 shown in Fig. 2. In the fourth embodiment, the calculation unit 2 shown in Fig. 2 acquires reflected light received by the transceiver unit 1. Based on this reflected light, the calculation unit 2 calculates the "arithmetic mean height Sa," "skewness Ssk," and "kurtosis Sku" of the surface of the water-repellent coating film P.

[0072] Specifically, the calculation unit 2 calculates the arithmetic mean height Sa1, skewness Ssk1, and kurtosis Sku1 of the surface of the water-repellent coating film P before dust is sprinkled on the water-repellent coating film P. Sa1, Ssk1, and Sku1 are examples of first measurement data measuring the unevenness of the coating film surface. That is, the first measurement data includes the first arithmetic mean height Sa1, first skewness Ssk1, and first kurtosis Sku1 of the water-repellent coating film P, which were measured before the water-repellent coating film P was exposed to a dusty environment.

[0073] The calculation unit 2 calculates the arithmetic mean height Sa2, skewness Ssk2, and kurtosis Sku2 of the surface of the water-repellent coating film P after dust has been sprinkled on the water-repellent coating film P. Sa2, Ssk2, and Sku2 are examples of second measurement data that measure the uneven state of the coating film surface after exposing the water-repellent coating film P to a dusty environment. That is, the second measurement data includes the second arithmetic mean height Sa2, second skewness Ssk2, and second kurtosis Sku2 of the water-repellent coating film P, which were measured after exposing the water-repellent coating film P to the dusty environment.

[0074] The calculation unit 2 calculates the amount of change in the arithmetic mean height Sa, skewness Ssk, and kurtosis Sku of the surface of the water-repellent coating film P before and after dusting the water-repellent coating film P, and evaluates which parts of the water-repellent coating film P, which has an uneven surface, are prone to adhesion of dirt based on the amount of change (second difference ΔSa, third difference ΔSsk, fourth difference ΔSku). That is, the calculation unit 2 calculates the second difference ΔSa, third difference ΔSsk, and fourth difference ΔSku between the first measurement data and the second measurement data, and evaluates the degree of contamination of the water-repellent coating film P based on these differences. The calculation unit 2 evaluates whether the dust has adhered to a concave or convex portion of the water-repellent coating P based on the difference between the first arithmetic mean height Sa1 and the second arithmetic mean height Sa2 (second difference ΔSa), the difference between the first skewness Ssk1 ​​and the second skewness Ssk2 (third difference ΔSsk), and the difference between the first kurtosis Sku1 and the second kurtosis Sku2 (fourth difference ΔSku). This will be explained in detail below.

[0075] The arithmetic mean height Sa is the average value of the average height difference from the mean plane, and can be expressed by the following formula (2).

[0076] In equation (2), "Z" is a coordinate perpendicular to the XY plane.

[0077] The skewness Ssk is a parameter relating to the height distribution, and can be expressed by the following equation (3).

[0078] In equation (3), "Sq" is the root mean square height, and "Z" is the coordinate perpendicular to the XY plane.

[0079] The kurtosis Sku is a parameter relating to the tip shape of the peaks and valleys, and can be expressed by equation (4) below.

[0080] In equation (4), "Sq" is the root mean square height, and "Z" is a coordinate orthogonal to the X-Y plane.

[0081] 11A, 11B, and 11C are explanatory diagrams showing the state when dust is sprinkled onto a water-repellent coating film P having an uneven surface 41, causing dirt 42 to adhere to the water-repellent coating film P. FIG. 11A shows the state in which dirt 42 adheres to the convex portions 41a of the surface 41, with FIG. 11A(a) showing the state before dust is sprinkled and FIG. 11A(b) showing the state after dust is sprinkled. FIG. 11B shows the state in which dirt 42 adheres to the concave portions 41b of the surface 41, with FIG. 11B(a) showing the state before dust is sprinkled and FIG. 11B(b) showing the state after dust is sprinkled. FIG. 11C shows the state in which dirt 42 adheres to both the convex portions 41a and the concave portions 41b of the surface 41, with FIG. 11C(a) showing the state before dust is sprinkled and FIG. 11C(b) showing the state after dust is sprinkled.

[0082] As shown in FIG. 11A, when dust stains 42 adhere to convex portions 41a of surface 41, the difference ΔSa (=Sa2-Sa1; second difference) between the arithmetic mean height Sa1 (first arithmetic mean height) before the stain adheres (FIG. 11A(a)) and the arithmetic mean height Sa2 (second arithmetic mean height) after the stain adheres (FIG. 11A(b)) increases.

[0083] As shown in Figure 11B, when dust contaminants 42 adhere to the recesses 41b of the surface 41, the difference ΔSa (= Sa2 - Sa1) between the arithmetic mean height Sa1 before the contaminants adhere (Figure 11B(a)) and the arithmetic mean height Sa2 after the contaminants adhere (Figure 11B(b)) decreases. Also, the difference ΔSsk (= Ssk2 - Ssk1; third difference) between the skewness Ssk1 ​​(first skewness) before the contaminants adhere and the skewness Ssk2 (second skewness) after the contaminants adhere increases. The difference ΔSku (= Sku2 - Sku1; fourth difference) between the crustosis Sku1 (first crustosis) before the contaminants adhere and the crustosis Sku2 (second crustosis) after the contaminants adhere decreases.

[0084] As shown in Figure 11C, when dust contaminants 42 adhere to both the convex portions 41a and concave portions 41b of the surface 41, the arithmetic mean height Sa1 before the contaminants adhere (Figure 11C(a)) and the arithmetic mean height Sa2 after the contaminants adhere (Figure 11C(b)) hardly change, and the difference between them ΔSa (= Sa2 - Sa1) is almost zero. Similarly, the difference between skewness Ssk1 ​​and Ssk2 ΔSsk and the difference between kurtosis Sku1 and Sku2 ΔSku are also almost zero. Furthermore, even when there is almost no contaminants 42 adhering to the surface 41, ΔSa, ΔSsk, and ΔSku are almost zero. In the contamination level evaluation method according to the fourth embodiment, the locations where contaminants adhere to the uneven surface are evaluated based on the three conditions shown in Figures 11A to 11C.

[0085] Next, the processing procedure for the contamination level evaluation method according to the fourth embodiment will be explained with reference to the flowchart shown in Figure 12. First, in step S61 of Figure 12, the transmitting / receiving unit 1 irradiates the surface of the water-repellent coating P applied to the sample 10 with laser light and receives the reflected light before sprinkling dust (for example, carbon black). Based on the reflected light, the calculation unit 2 calculates the arithmetic mean height Sa1, skewness Ssk1, and kurtosis Sku1 of the surface of the water-repellent coating P using equations (2) to (4) described above.

[0086] In step S62, the operator sprinkles dust onto the surface of the water-repellent coating P. For example, carbon black can be used as the dust.

[0087] In step S63, the transmitting / receiving unit 1 irradiates the surface of the water-repellent coating P after dust has been sprinkled on it with laser light and receives the reflected light. Based on the reflected light, the calculation unit 2 calculates the arithmetic mean height Sa2, skewness Ssk2, and kurtosis Sku2 of the surface of the sample 10 using equations (2) to (4) described above.

[0088] In step S64, the calculation unit 2 calculates the difference in arithmetic mean height ΔSa (= Sa2 - Sa1) before and after dust adhesion, the difference in skewness ΔSsk (Ssk2 - Ssk1), and the difference in kurtosis ΔSku (= Sku2 - Sku1).

[0089] In step S65, the evaluation unit 3 determines whether the arithmetic mean height Sa has increased based on the difference ΔSa. If it has increased (S65; YES), the process proceeds to step S66; otherwise (S65; NO), the process proceeds to step S67.

[0090] In step S66, the evaluation unit 3 determines that dirt 42 is adhering to the protrusions 41a on the surface 41 of the water-repellent coating P, as shown in Figure 11A. The evaluation unit then outputs this determination result to the outside, and the process ends.

[0091] In step S67, the evaluation unit 3 determines whether the difference ΔSa has decreased, the difference ΔSsk has increased, and the difference ΔSku has decreased. If the above conditions are met (S67; YES), the process proceeds to step S68; otherwise (S67; NO), the process proceeds to step S69.

[0092] In step S68, the evaluation unit 3 determines, as shown in Figure 11B, that dirt 42 is attached to the recess 41b of the surface 41 of the water-repellent coating P. Afterward, this determination result is output externally, and the process ends.

[0093] In step S69, the evaluation unit 3 determines whether the difference ΔSa, the difference ΔSsk, and the difference ΔSku are substantially 0. If the above condition is met (S69; YES), the process proceeds to step S70; if not (S69; NO), the process ends.

[0094] In step S70, the evaluation unit 3 determines that dirt 42 is present on both the convex portions 41 a and the concave portions 41 b of the surface 41 of the water-repellent coating film P, as shown in Fig. 11C, or determines that there is no dirt. Thereafter, this determination result is output to the outside, and the process ends.

[0095] In this way, the contamination level evaluation method according to the fourth embodiment evaluates the locations of the water-repellent coating P having an uneven surface where the dirt 42 adheres, based on the differences between the arithmetic mean height Sa, skewness Ssk, and kurtosis Sku on the surface of the water-repellent coating P. This makes it possible to evaluate the locations of the dirt 42 adherence with a very simple method and with high accuracy.

[0096] In the fourth embodiment described above, the arithmetic mean height Sa is used, but the developed interface area ratio Sdr shown in (1) above may be used instead of the arithmetic mean height Sa. That is, the first developed interface area ratio Sdr1, the second developed interface area ratio Sdr2, and the difference ΔSdr between them (= Sdr2 - Sdr1; first difference) may be used.

[0097] The evaluation device 100 of the present embodiment described above can be, for example, a general-purpose computer system including a CPU (Central Processing Unit, processor) 901, a memory 902, a storage 903 (HDD: Hard Disk Drive, SSD: Solid State Drive), a communication device 904, an input device 905, and an output device 906, as shown in FIG. 13 . The memory 902 and the storage 903 are storage devices. In this computer system, the CPU 901 executes a predetermined program loaded on the memory 902, thereby realizing each function of the evaluation device 100.

[0098] The evaluation device 100 may be implemented on a single computer, or on multiple computers. Furthermore, the evaluation device 100 may be a virtual machine implemented on a computer.

[0099] The program for the evaluation device 100 can be stored in a computer-readable recording medium such as a HDD, SSD, USB (Universal Serial Bus) memory, CD (Compact Disc), or DVD (Digital Versatile Disc), or can be distributed via a network. The computer-readable recording medium is, for example, a non-transitory recording medium.

[0100] This disclosure is not limited to the embodiments described above, and numerous modifications are possible within the scope of its essence.

[0101] 1 Transmit / receive unit 2 Calculation unit 3 Evaluation unit 4 Output unit 10 Sample 11, 21, 23, 31, 41 Surface 11a, 23a, 31a, 41a Convex parts 11b, 23b, 31b, 41b Concave parts 12, 22, 32, 42 Dirt 100 Evaluation device P Water-repellent coating (coating film)

Claims

1. A contamination evaluation method for evaluating the degree of contamination of a coating film, comprising: acquiring first measurement data measuring the unevenness of the surface of the coating film; acquiring second measurement data measuring the unevenness of the surface of the coating film after exposing the coating film to a dusty environment; calculating the difference between the first measurement data and the second measurement data; and evaluating the degree of contamination of the coating film based on the difference.

2. The contamination evaluation method according to claim 1, wherein the first measurement data includes a first unevenness frequency distribution of the surface of the coating film before the coating film is exposed to the dusty environment, and the second measurement data includes a second unevenness frequency distribution of the surface of the coating film after the coating film is exposed to the dusty environment, and the contamination level of the coating film is evaluated based on the difference between the first unevenness frequency distribution and the second unevenness frequency distribution.

3. The contamination evaluation method according to claim 1, wherein the first measurement data includes a first unfolded interface area ratio of the coating surface before the coating is exposed to the dusty environment, the second measurement data includes a second unfolded interface area ratio of the coating surface after the coating is exposed to the dusty environment, a first difference is calculated between the first unfolded interface area ratio and the second unfolded interface area ratio, and the contamination level of the coating is evaluated based on the first difference.

4. The contamination level evaluation method according to claim 1, wherein the first measurement data includes at least one of a first unfolded interface area ratio and a first arithmetic mean height of the coating film, a first skewness, and a first crustosis, measured before the coating film is exposed to the dusty environment; the second measurement data includes at least one of a second unfolded interface area ratio and a second arithmetic mean height of the coating film, a second skewness, and a second crustosis, measured after the coating film is exposed to the dusty environment; and the method evaluates whether dust has adhered to any recesses or protrusions in the coating film based on at least one of a first difference between the first unfolded interface area ratio and the second unfolded interface area ratio, and a second difference between the first arithmetic mean height and the second arithmetic mean height, a third difference between the first skewness and the second skewness, and a fourth difference between the first crustosis and the second crustosis.

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