JPH03107704A - Film thickness variation measuring instrument - Google Patents

Abstract

PURPOSE:To evaluate variation in the thickness of a filmy body continuously and speedily by detecting reflected light beams, reflected by small piece bodies which are irradiated with a light source at a specific angle and dispersed in the filmy body, by a photodetector. CONSTITUTION:The filmy body 2 which has many light-reflective small bodies 3 dispersed in a light-transmissive substrate with variable thickness is irradiated with the light source 4 at an angle. The photodetector 5 is provided at a specific position about the filmy body 2 and detects reflected light beams reflected by the small piece bodies 3 which are irradiated with the light source 4 and dispersed in the filmy body 2. When the thickness varies owing to swelling, the difference between reflected light beams detected by the photodetector 5 before and after the variation is inputted to an arithmetic means consisting of a microcomputer, etc., to find variation in the dispersion state of the small piece bodies 3 dispersed in the substrate of the filmy body 2 which varies in thickness, thereby operating the quantity of the variation in the thickness of the filmy body 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a film thickness change measuring device, and more specifically, the present invention relates to a film thickness change measuring device, and more specifically, it is a method for measuring film thickness changes that occur when film-like objects such as paint films, thin films, and thin sheets expand due to various causes. The present invention relates to a film thickness change measuring device for measuring film thickness change phenomena such as shrinkage and shrinkage by optical means.

[Conventional technology]

Membranes, especially membranes made of polymeric materials, often absorb water (or water vapor), organic solvents, etc. and swell, or these components evaporate or volatilize from the membrane. This may cause changes in film thickness, leading to defects (for example, when it comes to metallic paint films formed on the surface of automobile bodies, the base paint film absorbs the organic solvent components of the clear coat layer and swells, resulting in The gloss and color tone of the metallic paint film may change, causing paint defects.

Therefore, in research and manufacturing sites for metallic coatings, it is desired to establish an appropriate swelling evaluation technique in order to predict such swelling phenomena and take countermeasures.

In response to such demands, conventional techniques include directly measuring the amount of swelling of the membrane with a micrometer or dial gauge, or measuring the increase in weight due to swelling with a precision balance and converting it into the amount of swelling. There is technology.

[Problem to be solved by the invention]

However, in the above-mentioned method of measuring using a gauge, balance, etc., the film-like body is measured in the state in which it is actually used (for example, in the state in which a metallic paint film is formed on the surface of an automobile body). , and it is difficult to measure without destroying or damaging the membranous body, and - for boat fishing, measurements must be made on a separately prepared test piece. For this reason, it is not possible to obtain an evaluation based on the usage conditions, resulting in a lack of reliability.

Furthermore, when the film-like body to be evaluated is integrated with other film-like bodies or deposits (for example, a clear coat layer is overlaid on the base paint layer in a metallic paint film).

), its entire thickness and weight are measured, making it impossible to obtain an accurate evaluation. In order to ensure accurate evaluation, it is necessary to remove other membranous bodies and deposits without destroying or damaging the membranous body that is the subject of evaluation.
Such operations involve considerable difficulty.

Furthermore, in the above-mentioned conventional technology, the test piece is removed from the swelling phenomenon system each time a measurement is performed, so the progress of the phenomenon is interrupted at that point, making it unsuitable for continuous evaluation over time. On the other hand, when evaluating the swelling of a membranous material, it is necessary to evaluate not only the absolute amount of swelling (difference between the start and end of swelling) but also the swelling behavior (observation of the progress of swelling over time). There are many cases. However, with the above-mentioned conventional technology, it takes a considerable amount of time for each measurement, and on the other hand, the swelling of the membranous material often progresses rapidly within a relatively short period of time, for example, about 30 minutes. Even if you try to perform continuous evaluation on the same test piece over time, it will not be possible to keep up with the time.

Therefore, the present invention enables continuous and rapid evaluation of changes in the thickness of a membrane-like body, and also enables evaluation of changes in the thickness of only a specific membrane-like body in a multilayered structure of membrane bodies. The object of the present invention is to provide a reliable evaluation technique that allows evaluations to be made in accordance with usage conditions.

The inventors of the present application have discovered that when a film-like material is made up of flat small pieces randomly dispersed in its matrix, when the film-like material changes in thickness due to swelling or contraction, the film-like material is dispersed in various orientations. We focused on the fact that each small piece changes its orientation so that it becomes more steeply sloped when it swells, and becomes more gently sloped when it contracts. The present invention was completed based on the knowledge that changes in the film thickness of a membrane-like body can be measured by statistical calculation if the amount of change is understood in a macroscopic manner.

[Description of the claimed invention]

(Configuration of the first invention) The configuration of the first invention for solving the above problems is a film in which a large number of light-reflecting small pieces are dispersed in a light-transmitting substrate whose thickness can be changed. A light source that irradiates light at an angle to the film-like body, and a reflection that is irradiated from the light source and reflected by the small pieces dispersed in the film-like body, which is arranged at a specific position with respect to the film-like body. A detection means for detecting light and a change in reflected light detected by the detection means before and after the change in thickness of the film-like body are calculated, thereby detecting the change in the thickness of the film-like body. This is a film thickness change measuring device comprising calculation means for calculating the amount of film thickness change of a film-like body by determining a change in the dispersion mode of small pieces dispersed in a substrate.

(Operations and Effects of the First Invention) The first invention having the above-mentioned structure is characterized in that when the thickness of the substrate of the membranous body changes due to swelling or other reasons, the thickness of the matrix of the small pieces dispersed in the matrix changes. Since the dispersion mode, especially the angle, changes, the detection means detects the change in the reflected light amount due to the change in the reflection mode of the reflected light emitted from the light source by the small pieces, and the calculation means detects the film shape based on the change in the reflected light amount. It measures changes in body thickness, and enables highly accurate measurements using a simple device.

Next, the principle of measuring thickness change according to the first invention will be described.

If a large number of small pieces are dispersed in the matrix of a film-like body, when a change in film thickness occurs, the small pieces will change their orientation in response to the amount of change. This state will be explained in more detail based on FIGS. 1(a) to (C).

As shown in FIG. 1(a), a large number of small pieces 3 (flat thin pieces, but shown in straight lines in the figure) are present in the matrix of a film-like body 2 with a thickness Expressed as

) are distributed. When this membrane-like body 2 becomes thick h2 as shown in FIG. 1(b) due to swelling etc., the large number of small pieces 3 each have an increase in thickness Δh (=b2 hl
), the orientation changes in the direction of a steeper slope. Now, as shown in Fig. 1(C), suppose that the small piece 3 of length l is oriented at an angle θ1 with respect to the X axis in the state before swelling, and its height in the y axis direction is al. . It is assumed that this small piece 3 is oriented at an angle θ2 with respect to the X-axis in the state after swelling, and its height in the y-axis direction is a2. In this case, the swelling rate h r (=hg/h
, ) and the swelling amount Δh c=h, -h, ) are given by the following equations (1) and (2), respectively.

h r = a 2 / a + = sin θ2/sin θ+ −−−−(1) Δ
h=to+(s i nθ, -5inθ1)...(2
) In equation (2), 1 is a known constant determined according to the initial value θ1 of the degree of inclination of the film-like body 2.

As described above, from the angle θ1 of the specific piece body 2 to the angle θ2
If the amount of change in orientation is known, the swelling rate hr or swelling amount Δh of the membrane 2 can be determined.

Now, the small pieces used in the present invention are usually extremely minute, and it is practically difficult to focus on one small piece and measure its orientation and the amount of change in orientation. However, the above-mentioned difficulties can be overcome by dispersing a large number of light-reflecting particles and macroscopically measuring changes in the overall orientation of these particles using optical means.

[Explanation 3 of Other Inventions of the First Invention Next, other inventions that make the first invention more specific will be described.

An explanation will be given based on FIG. 2 which shows an example of the hardware part in the configuration of the first invention in a simplified manner. , the intensity of the reflected light β by the small piece is measured by the light receiver 5 fixed in a predetermined reflection direction. The light source 4 is configured to be able to move on a guide rail (not shown) along an arc line t centered at the incident point λ while always pointing at the same incident point λ. For now, membranous body 2
Assuming that most of the small pieces inside are oriented horizontally, when the intensity of the reflected light β is continuously measured with the light receiver 5 while the light source 4 is moved along the arc line, ,
When the light source 4 is at the position shown by the solid line in FIG. 2, the measured value of the reflected light β in the specular reflection direction should show a peak. When the membranous body 2 swells and the horizontally oriented small pieces change their orientation in the direction in which they stand up, for example, when the light source 4 comes to the position shown by the imaginary line in FIG. The measured value of reflected light β begins to show a peak. In this way, if the moving position of the light source 4 at which the measured value of reflected light β shows a peak is continuously traced as the swelling of the film-like body 2 progresses, it is possible to substantially detect the change in the orientation of a single piece. I get the same result as tracing. That is, in FIG. 2, the fixed angle of the light receiver 5 is at an angle θβ with respect to the normal y on the incident point λ, and the position of the light source 4 is such that the measured value of the reflected light β shows a peak before swelling. The position of the light source 4 where the measured value of the reflected light β shows a peak after θα swelling with respect to the normal y is the normal y
Assuming that θα2 is the angle θ2 and θ2 in FIG. 1, the angles θ2 and θ2 in FIG. 1 are given by the following equations (3) and (4), respectively.

θ,=I/2(θβ−θα,) ,,, (3)θ
2=1/2 (θβ−θα2) ,, (From the above 41 points, if a calculation means such as a microcomputer with a circuit configuration as shown in Fig. 3 is used, the optical system shown in Fig. 2 can be used. It is possible to measure the swelling rate hr and the amount of swelling Δh of the membrane-like body 2. In FIG. The first arithmetic circuit is based on the values of θα1, θα2, and θβ, (3)
This circuit calculates the values of θ1 and θ2 using equations (4) and (4). Furthermore, the second arithmetic circuit calculates the h r % by equations (1) and (2) based on the values of θ1 and θ2.
This is a circuit that calculates the value of Δh. The values of hr and Δh are displayed on the display.

On the other hand, the swelling of the film-like body can also be evaluated using an optical system as shown in FIG. That is, in FIG. 4, a large oblique light α emitted from a light source 4 is irradiated onto a film-like body 2 formed on a base 1, and reflected light from a large number of small pieces is reflected by two pieces provided at predetermined positions. It is measured by the photoreceiver 5 of. For example, the light source 4 is at 30° with respect to the normal y on the incident point λ of the incident light α,
The two light receivers 5 are provided at an angle of 60° in the positive direction and the negative direction, respectively. In such an optical system, the closer the orientation of the small pieces is to the horizontal, the more the reflected light β1 in the positive direction
is relatively strong, and the reflected light β2 in the negative direction is relatively weak.

As the overall orientation of the small pieces changes in the upward direction, the reflected light β gradually weakens and the reflected light β gradually becomes stronger. Therefore, the amount of change in the orientation of the small pieces Δθ (=θ2−θI) when the membrane-like body swells is given by the following equation (5).

Δθ” K 2 ・Lβ2/Lβ1 ... (5
) In the above equation (5), Lβl and Lβ2 are the measured values of the reflected lights β1 and β2, respectively, and k2 is a constant that can be known empirically. By substituting this equation (5) into the equations (1) and (2), the swelling ratio hr and the swelling amount Δh can be determined. In this case as well, the calculation means is constructed in the same manner as shown in FIG. 3, except that the first calculation circuit performs calculations based on equation (5).

In the other inventions of the first invention described above, it is most desirable to calculate and display the swelling rate hr and swelling amount Δh of the film-like body. In some cases, it is possible to sufficiently evaluate the swelling of a membranous body by knowing only the change and without performing any subsequent calculations.

In the present invention having the above-mentioned functions and effects, if continuous measurement over time is performed over time before and after the change in film thickness, it is also possible to evaluate the swelling behavior of the film-like body. And since it is an optical measuring device, results can be obtained instantly.
Even if the film thickness of the film-like body changes rapidly in a short period of time, the measurement operation will not be unable to follow the change in time.

In addition, since the device of the present invention only applies a light beam to the membrane-like object to be measured, it can be used to
Moreover, it can be evaluated non-destructively and without contact. Therefore, reliable evaluation can be obtained.

Furthermore, even when the film-like object to be measured is integrated with other film-like objects or deposits, the device of the present invention can measure the film without removing these objects (in the state of the original multilayer structure). It is possible to measure and evaluate only the change in film thickness of the body.

Note that in actual measurements, there is a possibility that the measurement will be affected by light reflected by the surface of the film-like body or the surface of the base body when the film-like body is formed on a base body such as a steel plate. However, since these reflected lights remain unchanged before and after changes in the thickness of the film-like body, they do not become a factor that interferes with changes in measured values.

(Structure, operation, and effect of the second invention) Next, the structure, operation, and effect of the second invention, which further embodies the first invention, will be explained.

The above-mentioned "membrane-like material" refers to a thin sheet-like material, and may be either a soft material or a hard material. Examples of such film-like bodies include coating films formed on the surfaces of various substrates (automobile bodies, building walls, etc.), as well as packaging sheet materials and thin plates used for various purposes. .

The above-mentioned "membrane-like substance matrix" refers to a substance that constitutes the matrix of the membranous body. Therefore, the membrane substrate may be any material as long as it can be formed into a membrane, has a certain degree of light transmission, and causes a change in thickness as a membrane for some reason.

The phenomenon of thickness change of the membranous body does not matter what the cause is. For example, the base paint film absorbs the components of the clear paint and swells, the volatile components evaporate from the paint film layer and shrink, and the hygroscopic thin film material swells due to moisture absorption in response to changes in air humidity. Examples include the phenomenon of shrinkage due to drying.

Furthermore, through evaluation of these changes in film thickness, it is also possible to indirectly evaluate changes in the weight or quality I of the film-like body.

The above-mentioned "light-reflecting small piece" refers to a flat small piece that reflects light. Examples include metal flakes dispersed in metallic base coatings, but there are also other
It may also be a material that has both a certain degree of light reflection and some light transmission, such as mica flakes. Since the small pieces are to be dispersed in the membrane matrix, it is not preferable that the diameter in the planar direction is too large compared to the thickness of the membrane.

To form a film by dispersing light-reflecting particles in a light-transmitting film matrix, disperse the small pieces into the film matrix by hand or using an appropriate kneading or stirring device. It can be dispersed and painted onto the surface of the substrate using a brush or spray device, or it can be formed into a sheet using a forming roll or the like.

Next, the above-mentioned "light beam" is preferably a parallel light beam having a width of the irradiation range such that a statistically significant number of dispersed particles are included. However, it is also possible to use scattered light with a specified width of the irradiation range. There are no particular restrictions on the intensity or wavelength of the light beam, and there are no limitations on the irradiation angle of the light beam on the film-like body. In setting the width and direction of the irradiation range of such light rays, a lens for diffusing and converging the rays and a reflecting mirror for reversing the direction of travel of the rays are installed between the light source that emits the light rays and the film-like body. etc. may be installed.

The light reflected by the small piece is measured using a light receiver. Here, the light receiver may be any device that can capture the light reflected by the small piece and read the intensity of the reflected light.

When measuring reflected light by a light receiver in an optical system like the one shown in Figure 4, if you want to avoid specularly reflected light from the surface of a film or base material, It may be installed in a direction shifted by about 2° to 30' or more from the direction.

〔Example〕

Next, one embodiment of the present invention will be described.

In this example, the swelling behavior of the base paint layer of a metallic paint film formed on the surface of an automobile body by n-butanol, toluene, and a clear paint was evaluated using the optical system shown in FIG. 4. Note that n-butanol and toluene are both commonly used as components of clear paints.

First, a metallic base coating layer was formed on the surface of a steel plate for an automobile body by spray painting a metallic base coating material (Magicron, trade name, manufactured by Kansai Paint Co., Ltd.) in which metal pieces had been dispersed in advance.

Three rows of such base paint layer materials were prepared, and n-butanol, toluene, and clear paint (Magicron Clear, trademarked by Kansai Paint Co., Ltd.) were respectively applied to these using a doctor blade, and the materials were left at room temperature. .

Then, for 25 or 30 minutes immediately after applying the above n-butanol, toluene and clear paint,
The swelling behavior of the base coating layer was continuously evaluated using a film thickness change measuring device.

In FIG. 4, the sample is one in which a base coating layer 2 in which metal pieces are dispersed is formed on the surface of a steel plate 1 for an automobile body as described above, and n-butanol, n-butanol, A clear coat material 6 made of toluene or clear paint is applied. The light source 4 is installed so as to irradiate the sample 3 with incident light α, which is a parallel beam of constant width, from a direction inclined by 30 degrees with respect to the normal y to the surface of the sample. The first light receiver 5 is located in a direction tilted by 60 degrees to the same side as the light source 7 with respect to the normal y, and the second light receiver 5 is located in a direction tilted by 60 degrees to the opposite side to the light source 7. is set up. As these light receivers 5.5, detectors for a color difference meter GCD-100 manufactured by Murakami Color Technology Research Co., Ltd. were used. The photoreceiver 5.5 receives the above-mentioned incident light α.
It is installed with the incident part λ facing the sample.

Figures 5 to 7 show the changes in R (Lβ2/Lβ) over time for each of the above-mentioned samples in which n-butanol, toluene, or clear paint was applied on the base coating layer 2, respectively. In the figures, the horizontal axis shows the elapsed time in minutes after application of the clear coat material 6, and the vertical axis shows the value of R. In each figure, the clear coat made of n-butanol, toluene, or clear paint is used. The value of R decreased significantly immediately after the application of Material 6, and it was well evaluated that the swelling of the base coating layer 5 due to the absorption of Clear Coat Material 6 was progressing rapidly. Furthermore, since the R value in FIG. 6 decreased particularly rapidly and the amount of decrease was large, it was also evaluated that toluene was particularly likely to cause swelling of the base coating layer 5.

Next, in Figures 5 to 7, the value of R stops decreasing after 2 minutes to 7 minutes, starts to rise, and thereafter shows an increasing curve that asymptotically approaches an equilibrium value that is slightly lower than the initial value. There is. From such changes in the R value over time, it is said that after the above-mentioned swelling process is completed, the volatilization of the clear coat material 6 and its absorbed components into the base coating layer becomes dominant, causing the base coating layer to shrink. , evaluation results were obtained that were in good agreement with the inventors' reasoning.

[Brief explanation of drawings]

Figures 1 (a), (b), and (C) are diagrams showing the principle of changing the orientation of metal pieces, which is the premise of the present invention, and Figures 2 and 4 are simplified examples of the hardware portion of the present invention. A diagram showing the
FIG. 3 is a flowchart of the software portion of the present invention, and FIGS. 5 to 7 are graphs showing changes over time in the value of R when three types of clear coat materials are used in Examples.

Claims (1)

[Claims] a light source that irradiates light at an angle to a film-like body in which a large number of light-reflecting particles are dispersed in a substrate whose thickness can be changed; a detection means disposed at a specific position in the membrane body for detecting reflected light irradiated from a light source and reflected by the small pieces dispersed in the membrane body; Changes in the film thickness of the film-like body are determined by calculating the change in the reflected light detected by the detection means in the step 1 and determining the change in the dispersion mode of the small pieces dispersed in the substrate of the film-like body whose thickness has changed. 1. A film thickness change measuring device comprising: calculation means for calculating a quantity.