JP7745239B2 - Method for measuring adhesion strength of coating film - Google Patents

Description

This invention relates to a method for measuring the adhesion strength of a coating film, and more specifically to a method for measuring the adhesion strength of a coating film in which a fluidized layer is formed below an upper dry layer.

There are various types of foundations used in makeup, including cake, cream, and liquid types, but all of them are made from a base such as oil to which coloring ingredients such as pigments have been added. When applied, they have the effect of covering up blemishes, freckles, pores, etc., and smoothing the appearance of the skin surface.

When such foundations are applied to the skin, the surface dries to form a film, forming an upper dry layer, and underneath this a fluid layer made of an oily base is formed. Whether the foundation, which forms the upper dry layer and fluid layer, adheres firmly to the skin (in other words, whether the foundation does not float) is extremely important to the performance of the foundation. However, to date, no method has been proposed for directly measuring the adhesive strength of foundation, and adhesive strength has had to be estimated using numerical values for factors that affect the adhesive strength of foundation, such as the viscoelasticity of the materials contained in the foundation and the blending ratio of the base (see, for example, Patent Document 1).

JP 2020-132527 A

The present invention was made in consideration of these problems, and its purpose is to provide a method for measuring the adhesion strength of a coating film that can directly and accurately measure the adhesion strength of a coating film, such as a foundation, that forms a fluid layer below an upper dry layer.

As a result of trial and error in order to achieve the above-mentioned objective, the inventors discovered that when measuring the horizontal force acting on the cutting blade, which indicates the adhesion strength of a coating film, it is possible to directly and accurately measure the adhesion strength of a coating film by measuring the horizontal force in two steps: a first step in which the cutting blade reaches the interface with the substrate, and a second step in which the cutting blade, once it has reached the interface, is moved horizontally along the interface, thereby completing the present invention.

In order to achieve the above object, a method for measuring the adhesion strength of a coating film according to claim 1 of the present invention is a method for measuring the adhesion strength of a coating film in which a fluidized layer is formed under an upper dry layer, and comprises a pre-step of forming the coating film on the surface of a substrate having a flat surface, and a measuring step of measuring the horizontal force acting on the coating film while cutting the cutting blade into the coating film using a measuring device having a structure in which a cutting blade can move relatively along two axes in horizontal and vertical directions, allowing the vertical force acting on the cutting blade to be set arbitrarily, and equipped with a horizontal force measuring means for measuring the horizontal force acting on the cutting blade, wherein the measuring step comprises applying a vertical force to the cutting blade with a first load, and The method comprises a first step of biaxially moving the cutting blade until the tip of the cutting blade reaches the surface of the base material, and a second step of horizontally moving the cutting blade while applying a vertical force to the cutting blade with a second load of the minimum weight necessary to maintain contact between the tip of the cutting blade and the surface of the base material, the method being characterized in that in the first step, the measurement results of the horizontal force measuring means transition through the following stages: a first stage in which the horizontal force increases as the cutting blade begins to cut, a second stage in which the increase in the horizontal force stops and becomes almost flat, and a third stage in which the horizontal force that had been flat begins to increase again, before switching to the second step .

The subject state measuring device according to the present invention employs the following configuration as a preferred embodiment thereof.
(1) The switching to the second step is performed after a certain time has elapsed since the transition to the third stage.
(2) The first load is applied by a weight that allows the cutting blade, which moves along at least two axes, to cut through the upper dry layer of the coating film and cut into the fluidized layer.

( 3 ) The second load is applied by a weight of the minimum weight that can maintain contact between the tip of the cutting blade and the surface of the base material.

(4) The measuring device is characterized by having a vertical displacement measuring means for measuring the vertical displacement of the cutting blade.

(5) The measurement step is carried out at different times after the previous step, thereby measuring the change over time in the upper dry layer of the coating film.

(6) The coating film is a foundation.

According to this invention, when measuring the adhesion strength of a coating film in which a fluidized layer is formed below an upper dry layer, the method involves two steps: a first step in which a first weight is used to apply a vertical force to the cutting blade, causing the cutting blade to perform biaxial movement until the tip of the cutting blade reaches the interface between the coating film and the substrate, and a second step in which a second weight of sufficient weight to maintain contact between the tip of the cutting blade and the surface of the substrate is used to apply a vertical force to the cutting blade, causing the cutting blade to perform uniaxial movement by moving horizontally. Therefore, once the cutting blade reaches the surface of the substrate in the first step, it moves horizontally in the second step without lifting off the surface (interface) of the substrate. Therefore, the horizontal force measured in the second step indicates the adhesion strength of the coating film to the substrate surface, allowing for direct measurement of the adhesion strength of the coating film.

In particular, in this second step, by using a second weight (critical normal load) that applies a vertical force to the cutting blade and that has the minimum weight necessary to maintain contact between the tip of the cutting blade and the surface of the substrate, the effects of friction caused by contact between the cutting blade and the substrate can be minimized, allowing the adhesion strength of the coating to be accurately measured.

FIG. 1 is a front view showing an example of a measuring device used to measure the adhesive strength of a coating film according to the present invention. FIG. 1 is a perspective view showing an example of a state in which a foundation, which is a test object, is applied to a substrate. 10 is a graph showing an example of the relationship between the cutting depth of the cutting blade and the horizontal force applied to the same test object. 10 is a graph showing another example of the relationship between the cutting depth of the cutting blade and the horizontal force applied to the same test object.

Embodiments of the present invention will now be described in detail with reference to the drawings. Note that the same reference numerals throughout the drawings indicate the same components or elements.

Figure 1 shows the schematic configuration of a measuring device 1 used to measure the adhesion strength of a coating film according to the present invention. The measuring device 1 has a structure in which the cutting blade 100 can move relatively along two axes, in the horizontal and vertical directions, the vertical force acting on the cutting blade 100 is set by the weight of the weight 12, and it is equipped with a horizontal force measuring means 4 that measures the horizontal force acting on the cutting blade 100.

More specifically, this measuring device 1 is primarily composed of a base 2, a support column 3 attached to the base 2, a horizontal force measuring means 4 for measuring the horizontal load acting on the cutting blade 100, an arm 5 swingably supported by the support column 3, a tool holder 6 for detachably holding the cutting blade 100, a mounting table 7 for placing a weight 12 that applies a vertical load to the cutting blade 100, a chuck 8 for holding the test object W, a contact angle adjustment unit 9 for adjusting the contact state between the test object W and the tip (cutting edge) of the cutting blade 100, a horizontal drive mechanism 10 for moving the test object W horizontally relative to the cutting blade 100, and a control unit 11.

The base 2 is the base of the device, having a horizontal surface, on which the support unit 3, horizontal drive mechanism unit 10, etc. are mounted. In this embodiment, the base 2 is fixed onto the device support stand 13.

The support column 3 is a column-shaped member mounted vertically on the surface of the base 2. A blade receiver 15 is provided at the upper end of the support column 3, which engages with a fulcrum blade 14 provided on the arm 5 to support the arm 5 so that the arm 5 can swing; this blade receiver 15 forms the swing fulcrum for the arm 5. Specifically, a blade support groove 16 is formed on the upper end surface of the blade receiver 15, which engages with the cutting edge of the fulcrum blade 14; the cutting edge of the fulcrum blade 14 is housed within this blade support groove 16.

The support column 3 is also equipped with a lifting stage 17 that adjusts the height of the blade receiving portion 15. The lifting stage 17 is designed to adjust the height of the blade receiving portion 15 up and down (vertically), and by adjusting the height of this lifting stage 17, the height of the horizontal force measuring means 4 (described below) and, further, the height of the tip of the cutting blade 100 can be adjusted.

The horizontal force measuring means 4 is composed of a measuring device (e.g., a load cell) that converts the horizontal force (horizontal force) acting on the cutting blade 100 into an electrical signal, and is connected to the support section 3 so that it can move up and down. In this embodiment, one end (the lower part on the back side) of the horizontal force measuring means 4 is connected to the support section 3 via a slider 18, and this slider 18 allows the measuring section 4 to move freely up and down (vertically). The horizontal force measuring means 4 is electrically connected to the control section 11, and the measurement results by the horizontal force measuring means 4 are input to the control section 11.

The arm 5 is a member that serves as a balance beam for suspending the horizontal force measuring means 4 in a balance mechanism that uses the blade receiving portion 15 (fulcrum blade 14) as a swing fulcrum, and is equipped with an adjustment weight 19 for balance adjustment at one end and a hanging portion 20 for suspending the horizontal force measuring means 4 at the other end.

The arm 5 is equipped with an arm leveling mechanism 30 that adjusts the arm 5 to a horizontal position. The arm leveling mechanism 30 mainly comprises a micrometer 28 that moves a horizontal adjustment bar 29, which is positioned to maintain a horizontal position, up and down, and the arm leveling bar 29 that abuts the arm 5 from above at equidistant positions (two positions in the illustrated example) on either side of the fulcrum blade 14. By operating the micrometer 28 to lightly press the arm leveling bar 29 against the arm 5, the arm 5 can be forced to a horizontal position. Zeroing the displacement sensor 25 (described below), i.e., adjusting the vertical position of the displacement sensor 25, is performed with the arm 5 forcibly maintained horizontal by the arm leveling mechanism 30.

The adjustment weight 19 is a weight used to balance the arm unit 5 when the horizontal force measuring means 4 is suspended from the suspension unit 20. In this embodiment, the adjustment weight 19 is attached to one end of the arm unit 5 so that it can slide left and right (horizontally) using the slide mechanism 50. The arm unit 5 is configured to be balanced by making it possible to change the distance from the fulcrum blade 14 to the adjustment weight 19.

The hanging part 20 is a component for detachably attaching the horizontal force measuring means 4 to the other end of the arm part 5. In this embodiment, this hanging part 20 is made up of metal rings connected in a chain shape, with one end connected to the other end of the arm part 5 and the other end connected to the upper end of the horizontal force measuring means 4, thereby suspending the horizontal force measuring means 4 from the arm part 5.

Also, approximately in the center of the arm portion 5, there is a fulcrum blade 14 that forms a swinging fulcrum that allows the arm portion 5 to function as a balance beam, and the cutting edge of this fulcrum blade 14 is supported by the blade support groove 16 of the blade receiving portion 15.

The tool holder 6 is a clamping device for detachably holding the cutting blade 100, and as shown in FIG. 1, is provided on the surface of the horizontal force measuring means 4 opposite the surface facing the support section 3, so as to hold the cutting blade 100 facing downward. Here, as described above, the horizontal force measuring means 4 on which the tool holder 6 is provided is suspended from the hanging section 20 of the arm section 5 and connected to the support section 3 by the slider 18 so that it can move up and down. Therefore, the height position of the tool holder 6 can be adjusted by adjusting the vertical position of the horizontal force measuring means 4.

In this regard, the measuring device 1 of this embodiment is equipped with a vertical displacement measuring means 25 (for example, a measuring device capable of measuring displacement on the nano-order, such as a capacitance displacement meter or laser displacement meter) that measures the vertical displacement (vertical displacement) of the cutting blade 100, and the measurement results of the vertical displacement measuring means are also input to the control unit 11. 26 denotes a displacement sensor position adjustment mechanism for adjusting the vertical position of the displacement sensor 25. In this embodiment, this displacement sensor position adjustment mechanism 26 is attached to the support part 3, and the vertical position of the displacement sensor 25 can be adjusted by adjusting the sensor position adjustment mechanism 26.

The cutting blade 100 preferably has a cutting edge made of a superhard material, such as a cemented carbide or cemented diamond. As described below, in this embodiment, horizontal force is measured using a foundation as the test object W, so a cutting blade 100 with a tip radius of 500 nm to 7 μm is preferably used. Note that in the horizontal force measurements shown in Figures 3 and 4, described below, a cutting blade made of CBN (Cubic Boron Nitride) with a tip radius of approximately 5 μm was used.

The mounting table 7 is a space for placing a weight 12 that adjusts the vertical force applied to the cutting blade 100. It is located above the tool holder 6, and the weight of the weight 12 placed on this mounting table 7 acts on the cutting blade 100 as a vertical load. Therefore, the vertical force applied to the cutting blade 100 can be freely (arbitrarily) set by adjusting the weight of the weight 12 placed on the mounting table 7.

The chuck unit 8 is a chuck device that detachably holds the test object W, and is positioned below the tool holder 6. Therefore, by adjusting the height position of the tool holder 6, the tip of the cutting blade 100 can be caused to act on the test object W. Note that in this embodiment, a vacuum base that adsorbs and holds the test object W is used as the chuck unit 8, but chuck mechanisms other than a vacuum base (such as a mechanical chuck device or an electrostatic chuck) may also be used as long as they are capable of detachably holding the test object W.

The contact angle adjustment unit 9 is a mechanism that finely adjusts the angle of the chuck unit 8 to adjust the contact state between the specimen W held in the chuck unit 8 and the cutting edge of the cutting blade 100, and in this embodiment is composed of a goniostage located below the chuck unit 8. By providing this goniostage, the measuring device 1 shown in this embodiment can position the surface of the specimen W parallel to the cutting edge of the cutting blade 100 to bring the specimen W and cutting blade 100 into close contact with no gaps, or can abut the specimen W against the cutting blade 100 at a predetermined inclination.

In the measuring device 1 shown in this embodiment, when aligning the cutting blade and the test piece W using the contact angle adjustment unit 9, a backlight 24 is irradiated onto the cutting edge (tip of the cutting blade) from the back side of the cutting blade, and the gap light is observed with a camera 31 positioned in front, allowing the cutting blade and the test piece W to be aligned.

The horizontal drive mechanism 10 is a mechanism for moving the specimen W held by the chuck 8 horizontally relative to the cutting blade 100. In this embodiment, it is primarily composed of a horizontal movement stage 21 that can move forward and backward toward the support 3, and a drive motor 22 that is drivingly connected to the horizontal movement stage 21 via a drive connection mechanism 23 such as a ball screw. In the horizontal force measurements shown in Figures 3 and 4 (described below), the horizontal force was measured while the horizontal movement stage 21 was moved horizontally at a speed of 0.5 μm/s. Incidentally, if this horizontal movement speed is slowed to approximately 0.01 μm/s, horizontal force can be measured without cutting into the substrate B, even if a diamond blade, which is sharper than CBN, is used as the cutting blade 100.

Specifically, the horizontal movement stage 21 is placed on the surface of the base 2, with the contact angle adjustment unit 9 and chuck unit 8 placed on top of this horizontal movement stage 21. The drive motor 22 is configured, for example, as a stepping motor, and is electrically connected to the control unit 11, which will be described later, so that the horizontal movement stage 21 can move forward and backward toward the support unit 3 under the control of the control unit 11.

The control unit 11 is a device that controls the drive motor 22 described above and processes the data measured by the horizontal force measurement means 4 and vertical displacement measurement means, and is composed of, for example, a personal computer. Therefore, this personal computer is equipped with at least software for controlling the drive motor 22 and software for processing the data measured.

In the measuring device 1 configured in this manner, a weight 12 corresponding to the vertical force to be applied to the cutting blade 100 is placed on the mounting table 7, and the horizontal drive mechanism 10 is driven to move the test piece W horizontally, thereby starting the cutting blade 100 from cutting into the test piece W. The horizontal force (horizontal force) applied to the cutting blade 100 during cutting is measured by the horizontal force measuring means 4, while the depth of the cutting blade 100's cut is measured by the vertical displacement measuring means.

Next, the measurement of the adhesive strength of a foundation using the measuring device 1 will be described.
When foundation is applied to the skin, the surface dries to form a film, forming an upper dry layer, and underneath this is formed a fluid layer composed of a base such as oil.

When the original applicant measured the adhesion strength of a coating film consisting of an upper dry layer and a fluid layer to a typical coating film, that is, measured the horizontal force acting on the cutting blade 100 while making a cut with the cutting blade 100, he found that the horizontal force acting on the cutting blade 100 transitions in the following order: stage 1, in which the horizontal force increases as the cutting blade 100 begins to cut; stage 2, in which the increase in the horizontal force stops and the horizontal force remains almost flat; and stage 3, in which the horizontal force that had remained flat begins to increase again.

The transition of this horizontal force was then examined in detail, taking into account factors such as the cutting depth of the cutting blade 100. It was found that the first stage corresponds to the stage when the cutting blade 100 is midway through cutting into the upper dry layer, the second stage corresponds to the stage when the tip of the cutting blade 100 has passed through the upper dry layer and reached the fluidized layer, and the third stage corresponds to the stage when the tip of the cutting blade 100 has reached the surface of substrate B and friction is occurring between it and the substrate surface.

The horizontal force acting on the cutting blade 100 during this third stage is a combined value of the adhesive force of the coating film and the frictional force with the substrate B. Therefore, the applicant believed that by reducing the vertical load (vertical force) acting on the cutting blade 100 to a minimum weight (critical vertical load) and minimizing the friction generated between the tip of the cutting blade 100 and the surface of the substrate B, it would be possible to measure the adhesive strength of the foundation to the substrate B, and conducted the following experiment.

First, two types of liquid foundation were prepared as the test specimen W. Each foundation was applied to a flat, planar acrylic substrate B, as shown in Figure 2. More specifically, in the experiment shown in Figure 3, one of the foundations was applied to substrate B at a thickness of 6 μm, and in the experiment shown in Figure 4, the other foundation was applied to substrate B at a thickness of 4 μm. For each experiment, horizontal force measurements were performed multiple times (two times each, (a) and (b)).

When cutting foundation with the cutting blade 100 to measure horizontal force, the tip (cutting edge) of the cutting blade 100 must be parallel to the surface of the foundation. However, because the surface of the foundation is uneven, the cutting edge of the cutting blade 100 cannot be aligned with the surface of the foundation. Therefore, in this embodiment, prior to cutting, the cutting edge is aligned on a portion of the acrylic substrate B where no foundation is applied, and then the test subject W is moved horizontally to position the cutting blade 100 on the foundation, bringing the cutting blade 100 close enough to touch the surface, and then cutting is performed. By aligning the cutting edge on the flat surface of substrate B in this way, cutting can be performed with the cutting edge parallel to substrate B, resulting in clean scraping of the foundation.

A: Experimental example of Figure 3:
First, a 7 g weight 12 is placed on the mounting table 7 as the first weight (load) (applying a 7 g vertical force to the cutting blade 100), and in this state, the cutting blade 100 is made to perform biaxial movement until the tip of the cutting blade 100 passes through the fluidized layer of the foundation and reaches the surface of the substrate B (hereinafter, this may be referred to as the "first step").

Here, the weight of the first weight is selected to be at least such that the cutting blade 100, which moves on two axes, can cut through the upper dry layer of the foundation and cut into the fluid layer (in other words, such a weight that the cutting blade 100 can transition from the first stage to the third stage described above by continuing its biaxial movement).

Specifically, the weight of the first weight is selected depending on the ingredients of the foundation that will be used as the test subject W, the size of the pigments contained in the foundation, and other factors. If this weight is too light, the cutting blade 100 will not reach the surface of the substrate B, resulting in foundation remaining on the surface of the substrate B and preventing an increase in horizontal force due to friction between the substrate B and the cutting blade 100 (stage 3). Conversely, if the weight is too heavy, the cutting blade 100 will cut into the substrate B. Therefore, it is necessary to select an appropriate weight depending on the type of test subject W, so that the first weight is neither too light nor too heavy.

When carrying out the first step, if an upper dry layer has not formed on the surface of the foundation, or if the upper dry layer has not dried sufficiently and is soft, the cutting blade 100 will reach the surface of the substrate B during the first step. Therefore, by monitoring the horizontal force acting on the cutting blade 100 or by monitoring the state of the cutting blade 100 with the camera 31, it is easy to check whether an upper dry layer has formed.

In both of the two experiments shown in Figure 3, the horizontal force acting on the cutting blade 100 increased to approximately 25-30 mN in the first stage due to the first process, then in the second stage the horizontal force remained stable, and then in the third stage the horizontal force began to increase again due to friction between the cutting blade 100 and the surface of the substrate B.

Then, in the third step, the state in which the horizontal force is increasing is continued for a while; in other words, the state in which the tip of the cutting blade 100 continues to scrape off the foundation while moving horizontally across the surface of the substrate B is continued for a while. At this time, the horizontal force acting on the cutting blade 100 is a numerical value that combines frictional force and adhesive force. Therefore, in the next step, to eliminate the frictional force, the relative horizontal movement of the cutting blade 100 is temporarily stopped, and while still stopped, the weight placed on the mounting table 7 is replaced from the first weight to a second weight (load) of 1 g, the 1 g weight 12. The cutting blade 100 is then moved horizontally again, and the horizontal force acting on the cutting blade 100 at this time is measured (hereinafter, this may be referred to as the "second step").

Whether the cutting by the cutting blade 100 has transitioned to the third stage (and further, the timing for switching from the first stage to the second stage) can be detected by observing the change in the horizontal force acting on the cutting blade 100 or the vertical displacement of the cutting blade 100 (in other words, the transition to the third stage can be determined when the horizontal force acting on the cutting blade 100 changes from a plateau to an increase). Furthermore, the reason this third stage is allowed to continue for a while is to ensure that the tip of the cutting blade 100 passes through the fluidized layer of the foundation and reaches the surface of the substrate B reliably, bringing the tip of the cutting blade 100 (cutting edge) into close contact with the surface of the substrate B.

The weight of the second weight used in this second step is selected to be the minimum weight necessary to maintain contact between the tip of the cutting blade 100, which is in close contact with the interface by the first weight, and the surface of the substrate B. In other words, the lightest possible weight is selected within the range in which the cutting blade 100 does not lift up even when moved horizontally.

The weight of this second weight is set appropriately depending on the contents of the subject W, such as the ingredients of the foundation and the type of pigment contained therein. In other words, this second weight needs to be as light as possible (low load) to minimize the effects of friction between the cutting blade 100 and the substrate B. However, if it is too light, the cutting blade 100 will lift up during horizontal movement, while if it is too heavy, the effects of friction will be greater or it will cut into the substrate B, so the weight of this second weight must also be selected appropriately.

In this way, by adjusting the weight of the weight 12, almost no friction (frictional resistance) occurs between the tip of the cutting blade 100 and the surface of the substrate B. Therefore, the horizontal force acting on the cutting blade 100 at this time is the horizontal force associated with the adhesion of foundation with the friction between the cutting blade 100 and the substrate B minimized, i.e., the adhesion strength of the foundation. This can be seen from the fact that almost the same measurement results (approximately 20 mN in the illustrated example) were obtained in the two experiments shown in Figure 3.

In addition, whether the measurement of the horizontal force in this second step was performed correctly, in other words, whether the cutting blade 100 scraped off the foundation correctly (that the foundation did not remain on the surface of the base material B and did not cut into the base material B), can be confirmed by using a microscope or the like to check the surface of the base material B after the second step, so the horizontal force acting on the cutting blade 100 can be accurately measured.

B: Experiment in Figure 4:
In the experiment shown in Fig. 4, a 5 g weight 12 was first placed on the mounting table 7 as the first weight, and in this state, the cutting blade 100 was made to perform biaxial movement until the tip of the cutting blade 100 reached the surface of the substrate B (first step). Note that the weight of the first weight at this time was set to a weight that would allow the biaxially moving cutting blade 100 to cut through the upper dry layer of the foundation and cut into the fluidized layer, as in the experiment shown in Fig. 3, and a 5 g weight 12 was used in this experiment.

In this experiment, the horizontal force acting on the cutting blade 100 increased to approximately 10-15 mN in the first stage as a result of this first step, and then in the second stage, the horizontal force remained stable, before beginning to increase again in the third stage.

In the experiment of Figure 4, as in the above, the horizontal force was allowed to increase for a period of time as the third stage, and then the weight placed on the mounting table 7 was replaced from the first weight to a second weight (a weight of the minimum weight necessary to maintain contact between the tip of the cutting blade 100 and the surface of the substrate B), the cutting blade 100 was moved horizontally, and the horizontal force acting on the cutting blade 100 at this time was measured (second step). In the experiment of Figure 4, since the specimen W was different from that in the experiment of Figure 3, a 1.5 g weight 12 was used as the second weight.

In the experiment shown in Figure 4, the measurement results for the second step were almost identical across both experiments (approximately 10-15 mN in the example shown), as shown in Figures 4(a) and (b), meaning that the adhesive strength of the foundation could also be measured in this case.

Thus, according to the present invention, when measuring the adhesion strength of a coating film in which a fluidized layer is formed below an upper dry layer, the method involves two steps: a first step in which a vertical force is applied to the cutting blade 100 using a first weight, causing the cutting blade 100 to perform biaxial movement until the tip of the cutting blade 100 reaches the surface of substrate B; and a second step in which a vertical force is applied to the cutting blade 100 using a second weight sufficient in weight to maintain contact between the tip of the cutting blade 100 and the surface of substrate B, causing the cutting blade 100 to perform uniaxial movement by moving horizontally. Therefore, once the cutting blade 100 reaches the surface of substrate B in step one, it moves horizontally in step two without lifting off the surface (interface) of substrate B. Therefore, the horizontal force measured in step two can be regarded as the adhesion strength of the coating film to substrate B, allowing the adhesion strength of the coating film to be measured directly.

In particular, in this second step, by using a weight of the minimum possible weight that can maintain contact between the tip of the cutting blade 100 and the surface of the substrate B as the second weight that applies a vertical force to the cutting blade 100, the effects of friction that occurs between the cutting blade 100 and the substrate B can be minimized, allowing the adhesion strength of the coating to be accurately measured.

The above-described embodiments merely represent preferred embodiments of the present invention, and the present invention is not limited to these, and various design modifications are possible within the scope of the present invention.

For example, in the above-described embodiment, the specimen W is moved horizontally when the cutting blade 100 cuts into the specimen W. However, the cutting blade 100 may be configured to move relatively along two axes, horizontally and vertically. For example, the cutting blade 100 may be configured to move horizontally. Furthermore, the detailed structure of the measuring device 1 used in the coating adhesion strength measuring method according to the present invention can be modified as appropriate, as long as the cutting blade 100 is configured to move relatively along two axes, horizontally and vertically, the vertical force acting on the cutting blade 100 is set by the weight of a weight, and the measuring device 1 is equipped with horizontal force measuring means 4 that measures the horizontal force acting on the cutting blade 100.

In addition, in the above-described embodiment, the measuring device 1 is equipped with a vertical displacement measuring means for measuring the cutting depth of the cutting blade 100, but it is also possible to omit the vertical displacement measuring means. When the measuring device 1 is equipped with a vertical displacement measuring means as in this embodiment, it becomes possible, for example, to use the measurement results of this vertical displacement measuring means to determine whether the cutting depth of the cutting blade 100 has transitioned to the third stage.

Furthermore, while the above-described embodiment shows a case where a foundation was used as the test subject W, the coating adhesion strength measurement method according to the present invention can also be applied to measuring the adhesion strength of coatings other than foundation (for example, paint, glue, adhesive, etc.) as long as the coating has a fluidized layer formed below the upper dry layer.

The method for measuring the adhesion strength of a coating film according to the present invention can measure the change in the adhesion strength of the coating film over time, for example, by performing the first and second steps multiple times while changing the elapsed time after the coating film to be tested (W) is formed on the substrate (B).

In the above-described embodiment, the weight 12 is replaced from the first weight to the second weight in the second step of the measurement process. However, when changing the weight from the first weight to the second weight, it is also possible to gradually reduce the weight of the weight 12 placed on the mounting table 7. For example, when changing the weight of the weight 12 from 7 g (the first weight) to 1 g (the second weight), it is also possible to gradually reduce the weight, such as 7 g, 5 g, 3 g, 2 g, and 1 g. When gradually reducing the weight of the weight 12 in this manner, the horizontal movement stage 21 is moved slightly after reducing the load until the horizontal force maintains approximately the same value. If the horizontal force value is maintained, the load is changed to the next lower load. This process is then repeated until the weight is reduced to the minimum weight (critical vertical load) that maintains contact between the tip of the cutting blade 100 and the surface of the substrate B, thereby changing the weight from the first weight to the second weight.

In addition, while the above-described embodiment shows a case where the vertical load acting on the cutting blade 100 is applied by the weight of the weight 12, the vertical load may be set using a method other than the weight 12 (for example, by using a piezoelectric element or the like to allow the vertical load setting to be changed). If the vertical load is configured to be freely changeable using a piezoelectric element or the like, the vertical load can be changed without temporarily stopping the horizontal movement, as is the case when setting the vertical load using the weight 12, and the adhesion strength of the coating film can be measured without taking into account the static friction that occurs when the horizontal movement is resumed.

REFERENCE SIGNS LIST 1 State measuring device 2 Base 3 Support section 4 Horizontal force measuring means 5 Arm section 6 Tool holding section 7 Placement table 8 Chuck section 9 Contact angle adjustment section 10 Horizontal drive mechanism section 11 Control section 12 Weight 14 Fulcrum blade 15 Blade receiving section 17 Lifting stage 18 Slider 19 Adjustment weight 20 Hanging section 21 Horizontal movement stage 22 Drive motor 100 Cutting blade B Substrate W Test object

Claims (7)

A method for measuring the adhesion strength of a coating film in which a fluidized layer is formed under an upper dry layer, comprising:
a pre-process of forming the coating film on a surface of a substrate having a flat surface;
a measuring step of measuring the horizontal force acting on the cutting blade while cutting the coating film, using a measuring device having a structure in which the cutting blade can move relatively in two axes in the horizontal and vertical directions, capable of arbitrarily setting the vertical force acting on the cutting blade, and equipped with a horizontal force measuring means for measuring the horizontal force acting on the cutting blade;
The measuring step
a first step of biaxially moving the cutting blade while applying a vertical force to the cutting blade with a first load until the tip of the cutting blade reaches the surface of the base material;
Following the first step, there is a second step of horizontally moving the cutting blade while applying a vertical force to the cutting blade with a second load of a minimum weight capable of maintaining contact between the tip of the cutting blade and the surface of the base material ,
In the first step, the measurement result of the horizontal force measuring means transitions in the order of a first stage where the horizontal force increases as the cutting blade starts to cut, a second stage where the increase in the horizontal force stops and becomes substantially flat, and a third stage where the horizontal force that had been flat starts to increase again, and then the process is switched to the second step.
A method for measuring the adhesion strength of a coating film. The method for measuring the adhesion strength of a coating film according to claim 1, characterized in that the switching to the second step is performed after the state in which the horizontal force has been increasing has continued for a while after the transition to the third stage. 3. A method for measuring the adhesion strength of a coating film according to claim 1 or 2, characterized in that the first load is applied by a weight that allows the cutting blade, which moves in two axes, to cut through the upper dry layer of the coating film and cut into the fluidized layer. 4. The method for measuring the adhesion strength of a coating film according to claim 1 , wherein the second load is applied by a weight of the minimum weight necessary to maintain contact between the tip of the cutting blade and the surface of the substrate. A method for measuring the adhesion strength of a coating film according to any one of claims 1 to 4, characterized in that the measuring device is equipped with a vertical displacement measuring means for measuring the vertical displacement of the cutting blade. A method for measuring the adhesion strength of a coating film according to any one of claims 1 to 5, characterized in that the measurement step is carried out at different times after the previous step, thereby measuring the change over time in the upper dry layer of the coating film. A method for measuring the adhesion strength of a coating film according to any one of claims 1 to 6, characterized in that the coating film is a foundation.