Deterioration testing device

Abstract

This deterioration testing device 10 comprises: a light source 11, a humidity adjuster 12, and a temperature adjuster 13 that perform a weathering test on a test article 100; a droplet dropping mechanism 14 that drops a droplet onto the test article 100; and an imaging device 16 that images the droplet dropped onto the test article 100. A control device 30 obtains the diameter of the droplet from an image obtained by imaging the droplet, estimates a contact angle from an amount of the droplet and a diameter of the droplet, and evaluates the water repellency of the test article 100.

Description

Deterioration Test Equipment

[0001] The present disclosure relates to a degradation testing device.

[0002] Fluorine-coated frying pans, umbrellas, and exterior walls coated with water-repellent paint repel water. Contact angle is an index used to quantify the state of wetting and repelling. Contact angle is defined as "the angle between the liquid surface and the solid surface where the free surface of a stationary liquid comes into contact with a solid wall." By introducing the concept of contact angle, it is possible to objectively and quantitatively express the quality of wetting with specific numerical values.

[0003] Typically, a droplet is first slowly dropped onto a solid surface and allowed to settle, and the contact angle is measured when the droplet is almost stationary on the solid surface (Non-Patent Document 1). The most basic method for measuring static contact angles is the droplet method. In this method, a dispenser is used to drop a tiny droplet of less than a few μL onto a solid surface, and an image is taken of the droplet from directly to the side with a CCD camera. The contact angle is calculated from this image by analyzing the droplet's outline.

[0004] The contact angle varies depending on the condition of the solid wall, and for example, as the solid wall deteriorates over time, the contact angle changes over time. For example, when a clean glass slide immediately after opening was left in the atmosphere and the contact angle was measured over time using the sessile drop method, it was reported that the contact angle began to decrease significantly after one day of exposure to the atmosphere and became almost constant after two months (Non-Patent Document 2).

[0005] Fukuyama, "Evaluation Method for Water Repellency," Evaluation Technology, 2009, Vol. 60, No. 1, pp. 21-26. "Evaluation of Surface Cleanliness by Contact Angle," Kyowa Kaimen Kagaku Co., Ltd., Internet (URL: https: / / www.face-kyowa.co.jp / science / literature / contactangle09.html).

[0006] However, Non-Patent Documents 1 and 2 do not disclose the simultaneous evaluation of accelerated deterioration due to environmental conditions and water repellency. Therefore, when the accelerated deterioration due to environmental conditions and the evaluation of water repellency are simultaneously performed, it is necessary to repeatedly perform weather resistance tests and evaluation of water repellency, which requires a lot of equipment and labor to perform the tests and evaluations.

[0007] The present disclosure has been made in view of the above circumstances, and an object thereof is to simultaneously carry out a weather resistance test and an evaluation of water repellency using a simple method.

[0008] A degradation test device according to one aspect of the present disclosure includes a weathering test section that performs a weathering test on a test specimen, a droplet dropping section that drops droplets onto the test specimen, an imaging section that captures an image of the droplets dropped onto the test specimen, and a determination section that calculates the diameter of the droplets from the captured image and estimates a contact angle from the amount of the droplets and the diameter to evaluate the water repellency of the test specimen.

[0009] According to the present disclosure, weather resistance testing and evaluation of water repellency can be carried out simultaneously using a simple method.

[0010] FIG. 1 is a diagram showing an example of the configuration of a degradation test device. FIG. 2 is a diagram showing an example of the configuration of a control device. FIG. 3 is a diagram showing an example of a droplet dropped on a test piece. FIG. 4 is a diagram showing an example of a droplet dropped on a test piece. FIG. 5 is a diagram for explaining a method for estimating a contact angle from the diameter of a droplet. FIG. 6 is a flowchart showing an example of the processing flow of the degradation test device. FIG. 7 is a diagram showing an example of a test piece onto which droplets have been dropped multiple times. FIG. 8 is a diagram showing an example of a test piece onto which droplets have been dropped multiple times. FIG. 9 is a diagram showing an example of degradation test results. FIG. 10 is a diagram showing an example of a test piece. FIG. 11 is a diagram showing an example of the hardware configuration of a control device.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0012] An example of the configuration of a degradation test apparatus 10 will be described with reference to Figure 1. The degradation test apparatus 10 shown in the figure has a hollow rectangular parallelepiped shape with an airtight structure and is installed on a flat floor. The degradation test apparatus 10 performs a weather resistance test on a test specimen 100 to examine deterioration of the water repellency of the test specimen 100. Inside the degradation test apparatus 10, a light source 11, a humidity regulator 12, a temperature regulator 13, a droplet dropping mechanism 14, a stand 15, and an imaging device 16 are arranged.

[0013] The light source 11 is disposed above the degradation test device 10 and irradiates the test specimen 100 with light simulating sunlight. The light source 11 irradiates light including light in the ultraviolet region. The light source 11 may irradiate light in the visible region and infrared region in addition to ultraviolet light. The light source 11 may be one that performs tests in accordance with "ISO 11341," "JIS K 5600-7-7," "JIS K 7350-2," etc. The light source 11 may be an ultraviolet fluorescent lamp, a xenon lamp, a sunshine carbon lamp, or a metal halide lamp. The above lamps may be combined with a filter to make the spectral radiation distribution of the emitted light closer to that of sunlight.

[0014] The humidity regulator 12 maintains the interior of the deterioration test device 10 at a predetermined humidity.

[0015] The temperature regulator 13 maintains the inside of the deterioration test device 10 at a predetermined temperature.

[0016] A weather resistance test of the test specimen 100 is carried out using a light source 11 , a humidity regulator 12 , and a temperature regulator 13 .

[0017] The droplet dispensing mechanism 14 dispenses droplets of any amount onto the test piece 100. The droplet dispensing mechanism 14 may dispense droplets at any time interval. Although two droplet dispensing mechanisms 14 are shown in FIG. 1, any number of droplet dispensing mechanisms 14 may be used.

[0018] The stage 15 is disposed below the droplet dropping mechanism 14 and places the test specimen 100 thereon. The stage 15 may be rotatable or movable so that the position at which the droplet is dropped onto the test specimen 100 can be adjusted.

[0019] The image capturing device 16 is, for example, a CMOS camera, and captures an image from above of the droplet dropped onto the test piece 100. The image capturing device 16 may be movable inside the degradation test apparatus 10.

[0020] Each part arranged inside the degradation test device 10 is controlled by a control device 30 .

[0021] An example of the configuration of the control device 30 will be described with reference to Fig. 2. The control device 30 shown in Fig. 2 includes a control unit 31, a processing unit 32, a determination unit 33, a display unit 34, and a storage unit 35.

[0022] The control unit 31 controls each unit of the degradation test apparatus 10 to conduct a weather resistance test, drip droplets onto the test specimen 100, and capture an image of the droplets dripped onto the test specimen 100. For example, when conducting a weather resistance test, the control device 30 controls the on / off and illuminance of the light source 11, and controls the humidity regulator 12 and the temperature regulator 13 so that the humidity and temperature inside the degradation test apparatus 10 are set to predetermined levels. The control device 30 controls the stage 15 to rotate or move, thereby adjusting the position of the test specimen 100 placed on the stage 15, so that droplets are dripped onto desired positions on the test specimen 100. The control device 30 controls the droplet dripping mechanism 14 to drip a desired amount of droplets onto the test specimen 100, and controls the imaging device 16 to capture an image of the droplets dripped onto the test specimen 100.

[0023] The processing unit 32 acquires the image of the droplet captured by the degradation test device 10, analyzes the image to determine the diameter of the droplet, and estimates the contact angle from the diameter. Well-known image processing techniques can be used for the process of analyzing the image to determine the diameter of the droplet.

[0024] 3 and 4 show examples of droplets 200A and 200B dropped on test specimens 100A and 100B. The upper diagram shows the test specimens 100A and 100B as viewed from the side, and the lower diagram shows the test specimens 100A and 100B as viewed from above. The contact angle θ of the droplet 200A A is the contact angle θ of the droplet 200B B In other words, the test piece 100A is more water-repellent than the test piece 100B. When the amounts of the droplets 200A and 200B are the same, the contact angle θ A , θ BThe larger the diameter d of the droplets 200A and 200B, A , d B becomes smaller.

[0025] The relationship between the amount (volume) of the dropped droplet, the diameter of the droplet, and the contact angle is stored in a database in the memory unit 35. The processing unit 32 refers to the memory unit 35 and estimates the contact angle from the amount and diameter of the droplet.

[0026] Alternatively, the processing unit 32 may determine the contact angle using the θ / 2 method, which regards the droplet 200 as a spherical indentation (a solid formed by cutting a sphere along a single plane) obtained by horizontally cutting a true sphere 250, as shown in Fig. 5, and determines the contact angle θ from the radius r and height h of the droplet 200 using the following formula:

[0027]

[0028] The volume V of a spherical indentation with a cut radius r and height h is expressed by the following formula.

[0029]

[0030] Since the volume V of the droplet 200 is known, the height h of the droplet 200 can be calculated by measuring the diameter d and determining the radius r. The contact angle θ can be obtained from the radius r and height h of the droplet 200 by the θ / 2 method.

[0031] The determination unit 33 determines the deterioration of the test specimen 100 based on the estimated contact angle. When the test specimen 100 deteriorates and its water repellency decreases due to the weather resistance test using the deterioration test device 10, the contact angle of the droplet decreases. The determination unit 33 determines the deterioration of the test specimen 100 based on the percentage of the contact angle relative to its initial value. For example, the determination unit 33 determines that the test specimen 100 has deteriorated when the contact angle becomes 70% or less of its initial value. Alternatively, the determination unit 33 may determine the deterioration of the test specimen 100 based on the absolute value of the contact angle rather than the rate of decrease in the contact angle.

[0032] The display unit 34 displays the results of the weather resistance test to determine whether the test specimen 100 has deteriorated. The display unit 34 may also display various information such as the captured image of the water droplet, the diameter of the water droplet determined from the image, and the contact angle estimated by the processing unit 32.

[0033] The storage unit 35 stores various information obtained during the weather resistance test and the evaluation results of the test specimen 100. The storage unit 35 may store the relationship between the amount of droplet, the diameter of the droplet, and the contact angle.

[0034] An example of the processing flow of the degradation test device will be described with reference to the flowchart of FIG.

[0035] In step S11, the control device 30 controls the degradation test device 10 to perform a weather resistance test for a predetermined time on the test specimens 100. For example, the temperature inside the housing is set to 38°C and the humidity to 50% RH, and the light source 11 is turned on to continuously irradiate the entire surroundings (360° directions) centered on the light source 11 with light simulating sunlight for A hours. This light is irradiated almost uniformly onto multiple test specimens 100 placed below the light source 11.

[0036] After the weather resistance test, in step S12, the control device 30 controls the degradation test device 10 to drip droplets onto the test specimen 100 and capture an image of the droplets dripped onto the test specimen 100. Specifically, the control device 30 controls the stage 15 to move the stage 15 on which the test specimen 100 is placed so that the location where the droplets are to be dripped is located below the droplet dripping mechanism 14. The control device 30 controls the droplet dripping mechanism 14 to drip a predetermined amount of droplets onto the test specimen 100. The control device 30 controls the imaging device 16 to capture an image of the droplets dripped onto the test specimen 100 from above.

[0037] In step S13, the control device 30 acquires the captured image from the deterioration test device 10, measures the diameter of the droplet, and estimates the contact angle.

[0038] In step S14, the control device 30 determines the decrease in the contact angle of the test specimen 100 as a percentage of the initial contact angle, and terminates the process when the contact angle becomes a predetermined percentage of the initial value or less. When weather resistance tests are performed on multiple test specimens 100 simultaneously, the process may be terminated when the contact angle of any of the test specimens 100 decreases to a predetermined value or less.

[0039] In step S15, the control device 30 determines whether the total test time of the weather resistance test has exceeded a predetermined time, and if the total test time has exceeded the predetermined time, ends the process.

[0040] If the total test time does not exceed the predetermined time, the control device 30 returns the process to step S11 and repeats the weather resistance test, the droplet dropping, and the contact angle estimation.

[0041] When repeating the process, the stage 15 may be moved to change the position where the droplets are dropped. For example, by placing the test piece 100 at the center of rotation of the stage 15 and rotating the stage 15 in a circumferential direction when repeating the process, the droplets 200 can be dropped circularly onto the test piece 100 as shown in FIG. 7 . Furthermore, by moving the stage 15 horizontally and vertically when repeating the process, the droplets 200 can be dropped onto the test piece 100 while shifting their positions, as shown in FIG. 8 . When the droplets 200 are dropped onto the test piece 100, the surface condition of the area where the droplets 200 are dropped changes from the condition before the drop. However, by dropping the droplets 200 sequentially onto different locations, the droplets 200 are not affected by the droplets 200 dropped previously. Conversely, the droplets 200 may be dropped continuously onto the same location to examine the effect of the droplets 200 dropped previously.

[0042] Figure 9 shows the results of a deterioration test conducted on specimens 1 to 4 with different contact angles, with the light irradiation time kept constant and the type, amount, and speed of the droplets kept constant. Figure 9 shows the initial contact angle, contact angle after the test, and rate of change in contact angle for specimens 1 to 4.

[0043] Specimens 1 to 4 were made by applying different super water-repellent paints to steel plates measuring 7 cm wide x 15 cm long.

[0044] Water was used as the droplet. The total test time was set to 10,000 hours, and the process shown in Figure 6 was repeated until the contact angle of any of specimens 1 to 4 reached 70% of its initial value. Before the total test time reached 10,000 hours, the contact angle of specimen 1 reached 70% of its initial value, so the test was terminated.

[0045] The results in Figure 9 make it possible to easily recognize the change over time in the water repellency of the test specimens in response to environmental conditions. For example, it can be seen that test specimen 1, although having a high initial contact angle, deteriorates in water repellency more quickly than test specimens 2 to 4. It can also be seen that test specimen 3 maintains sufficient water repellency even as deterioration due to environmental conditions progresses. By using the degradation test device 10 of this embodiment, it is possible to estimate the range of environmental conditions that the test specimen can withstand in a simple manner.

[0046] If the test object is super water-repellent, there is a possibility that the droplet will roll off the test object when it is dropped. Therefore, if the test object is super water-repellent, it is advisable to curve the test object 100 downward or to provide a depression in the test object 100, as shown in FIG. 10. This can eliminate the possibility that the droplet 200 will roll off the test object 100.

[0047] As described above, the deterioration test apparatus 10 of this embodiment includes the light source 11, humidity regulator 12, and temperature regulator 13 for conducting a weather resistance test on the test specimen 100, the droplet dispensing mechanism 14 for dispensing droplets onto the test specimen 100, and the imaging device 16 for capturing an image of the droplets dispensed onto the test specimen 100. The control device 30 determines the diameter of the droplets from the captured image, and estimates the contact angle from the amount and diameter of the droplets to evaluate the water repellency of the test specimen 100. This allows the weather resistance test and the evaluation of water repellency to be performed simultaneously.

[0048] The control device 30 described above can be, for example, a general-purpose computer system including a central processing unit (CPU) 901, a memory 902, a storage 903, a communication device 904, an input device 905, and an output device 906, as shown in Fig. 11. In this computer system, the control device 30 is realized by the CPU 901 executing a predetermined program loaded onto the memory 902. This program can be recorded on a non-transitory computer-readable recording medium such as a magnetic disk, an optical disk, or a semiconductor memory, or can be distributed via a network.

[0049] REFERENCE SIGNS LIST 10 Deterioration test device 11 Light source 12 Humidity regulator 13 Temperature regulator 14 Droplet dropping mechanism 15 Unit 16 Imaging device 30 Control device 31 Control unit 32 Processing unit 33 Determination unit 34 Display unit 35 Memory unit 100, 100A, 100B Test piece 200, 200A, 200B Droplet

Claims

1. A deterioration test device comprising: a weathering test section that performs a weathering test on a test specimen; a droplet dropping section that drops droplets on the test specimen; an imaging section that takes an image of the droplets dropped on the test specimen; and a determination section that calculates the diameter of the droplets from the image of the droplets and estimates the contact angle from the amount of the droplets and the diameter of the droplets to evaluate the water repellency of the test specimen.

2. A deterioration test device according to claim 1, wherein the weather resistance test and the evaluation of water repellency are repeated until the rate of decrease in the contact angle becomes equal to or less than a threshold value or the contact angle becomes equal to or less than a predetermined value.

3. A degradation test device according to claim 2, comprising a movable stage on which the test specimen is placed, and wherein the stage is moved so that the positions at which droplets are dropped vary when weather resistance tests and evaluation of water repellency are repeated.

4. A deterioration test device according to claim 1, comprising a memory unit that stores the relationship between the amount of droplets, the diameter of the droplets, and the contact angle, and the contact angle is estimated by referring to the memory unit.

5. A deterioration test device according to claim 1, wherein the contact angle is estimated by determining the height of the droplet from the amount of the droplet and the diameter of the droplet.

6. A degradation test device according to claim 1, wherein the weather resistance test section, the droplet dropping section, and the imaging section are all contained within a single housing.

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