JP6049006B2 - Super water-repellent surface emitting sensor - Google Patents

Description

  The present invention relates to a surface light emitting sensor such as a pressure sensitive paint (PSP), a temperature sensitive paint (TSP), a pH sensor and the like, which has water / ice / snow adhesion prevention and a moisture resistance function.

The surface emission sensor is a sensor that detects a light emission (fluorescence / phosphorescence) state that changes in accordance with an environmental state when the excitation light is irradiated, and measures the environmental state. A typical example of this type of sensor is a pressure-sensitive paint that measures pressure distribution. Attempts have been made to measure the pressure distribution on aircraft and rocket aircraft using this measurement technique, mainly using models in wind tunnels. This pressure distribution measurement using pressure-sensitive paint is applied to the model surface and observes the luminescence corresponding to the pressure of that part, and the detailed local data on the entire surface is obtained as image information using a CCD camera or the like. It has the feature that it can be obtained.
An example of a surface emitting sensor conventionally used is shown in FIG. The left airplane model is painted with pressure-sensitive paint (PSP) and temperature-sensitive paint (TSP) separately from the center. The photo on the right is an image of the pH sensor. The emission color varies depending on the pH degree, and the distribution state can be grasped as an image.

  The principle of pressure measurement using the above pressure-sensitive paint is the luminescence (fluorescence / phosphorescence) emitted by chemical substances such as porphyrins (PtTFPP, PtOEP, PdTFPP, etc.) with platinum or palladium as the central metal according to the oxygen partial pressure. ) The phenomenon is measured from the light emission state. In addition to the pressure sensitive paint (PSP), a temperature sensitive paint (TSP), a pH sensor, and the like are well known as surface emitting sensors. In addition, it is known that the pressure-sensitive paint has a characteristic change due to temperature, and the temperature-sensitive paint has a characteristic change due to pressure. Conventionally, it has been known that temperature compensation and pressure compensation are necessary. (See Patent Document 1). Further, it has been found that this surface light emitting sensor has properties such as responsiveness of light emission, sensitivity, and the like that deteriorate due to the influence of humidity and moisture. It is necessary to calibrate and correct the measured value for each experiment. As a result, the humidity control of the model coated with the paint must be strictly performed, and there are situations where the use is limited to only the measurement in the wind tunnel where the temperature and humidity are controlled.

  In order to improve responsiveness, if the coating film thickness is reduced, the coating amount is small and the amount of emitted light is reduced, making optical measurement difficult. Although the amount is large, there is also a problem that the time until the excitation light penetrates into the paint and emits light becomes long and the responsiveness deteriorates. In order to improve the responsiveness of the surface emitting sensor, a TLC plate with a porous surface on the base or an aluminum alloy with an anodized film is used to increase the contact area with the outside air (this is also the light emitting area). In some cases, however, the shape of the model serving as the measurement surface and the material to be used are limited, so that the application destination of the measurement is limited. In addition, the surface of this sensor has a problem that it has a problem in that it easily adsorbs moisture in the air due to the porous structure and material that increase the contact area with the outside air, and this causes the problem of affecting the light emission characteristics. I understood it.

Japanese Patent Laid-Open No. 2006-10517 “In-situ Measurement Method and Apparatus for Pressure-Sensitive Paint with Temperature Dependence Correction” Published on January 12, 2006

  The surface shape of the measurement surface is not limited by the shape of the model and the materials used, and the surface emission sensor is equipped with water / ice / snow adhesion prevention, moisture resistance and improved responsiveness of the surface emitting sensor. To provide a sensor.

The super water-repellent surface light emitting sensor of the present invention is mainly composed of fluororesin particles having a diameter of several tens of μm or less for generating a porous surface shape, and a small amount of light emitting paint, and for fixing on the basis thereof . A mixture of a small amount of methyl silicone having a small cohesive force between the molecules having methyl groups in the binder was applied to the object to be inspected.
In the super water-repellent surface emitting sensor of the present invention, PTFE is used for the fluororesin to generate a porous surface shape.
In one embodiment of the present invention, the luminescent paint uses a chemical substance having an oxygen quenching function.
In one embodiment of the present invention, the luminescent paint uses a chemical substance having a thermal quenching function.
In one embodiment of the present invention, the luminescent paint uses a chemical substance having pH dependency.
The coating material used for the super water-repellent surface emitting sensor of the present invention was a one-pack type, and the application to the test object was performed by spraying or brush coating.

The super water-repellent surface emitting sensor of the present invention has a porous surface shape by containing fluororesin particles such as PTFE, and by using a methyl silicone alkoxy oligomer that is a binder thereof, super water repellency, waterproof, The functions of moisture resistance, anti-icing, snow-proofing, oil resistance, chemical resistance, weather resistance and insulation are improved. As a result, the influence of humidity on the optical measurement can be largely eliminated, and the measurement can be performed not only in the laboratory where the environmental conditions are easy to prepare, but also outdoors.
By using an inorganic polymer that hydrolyzes and cures the dispersant (solvent) used in the paint and the polymer (binder) to be attached without the need of an organic solvent, it is highly safe and minimizes environmental impact, damage to organisms and workers. It became possible to limit.
Since the methyl silicone alkoxy oligomer as a binder is cured by moisture in the air, it can be used as a one-pack type paint.

It is a figure which shows a mode that the water droplet was each dripped at the super water-repellent PSP sensor of this invention, and TLC-PSP. It is a figure which shows the pressure sensitivity characteristic of the super water-repellent PSP which concerns on this invention. It is a figure explaining the experimental apparatus which gave the wall surface jet to the surface sensor, took the light emission image, and performed pressure distribution measurement. It is an image which compares the light emission intensity ratio when the humidity of the super water-repellent PSP and the TLC-PSP sensor according to the present invention is 20% and 80%. It is the graph which compared the emitted light intensity ratio about the super water-repellent PSP and TLC-PSP sensor which concern on this invention. It is a figure which shows the usage form of the conventional surface sensor (PSP, TSP, pH sensor).

  The present invention does not limit the shape of the model used as the measurement surface and the material used, and is provided with water / ice / snow adhesion prevention, moisture resistance function and improved response of the surface emitting sensor. The purpose of this is to provide a surface emitting sensor, so the material should be water and moisture resistant, and contact with the outside air to improve the response of the surface emitting sensor. Development was carried out with the goal of increasing the surface area. In order to improve the responsiveness of the surface emitting sensor, a TLC plate having a porous surface on the base or an aluminum alloy with an anodized film may be used to increase the contact area with the outside air. In view of the problem that the shape of the model used as the measurement surface and the materials to be used are limited, the application destination of the measurement is limited. We obtained knowledge that fluorine-based resin is appropriate as a material with no water interference and moisture resistance.

  A fluororesin is a substance known by the name of Teflon (registered trademark) and is a general term for plastics containing fluorine atoms. Fluorocarbon resins include PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), ETFE (tetrafluoroethylene / ethylene copolymer). Polymer), PVDF (polyvinylidene fluoride), PCTFE (polychlorotrifluoroethylene) and the like. The greatest feature of this fluororesin is its chemical resistance. Since it is completely stable to any acid, alkali and organic chemicals and does not erode or swell, it is unacceptable as a chemical resistant packing. It is reported that ozone resistance is good, weather resistance is not changed at all with respect to a 10-year exposure test, and hygroscopicity and water absorption are also 0.00%. In the present invention, particles having an average diameter of about 5 μm of a fluororesin having such properties are mixed into the paint to form a porous sensor surface, thereby increasing the contact area with the outside air. Since the fluororesin has a hygroscopic property and a water absorbing property of 0.00%, it is understood that there is no influence of humidity even if the contact area is increased. A surface sensor needs to be coated with a luminescent dye on the surface of the subject. In that case, after applying a paint in which the luminescent dye is uniformly dispersed in a liquid, the surface sensor must be in a state of stably adhering to the surface of the subject. Don't be. For that purpose, a solvent (or dispersant) and a binder are mixed to form a paint. In the present invention, the above-mentioned fluororesin particles are added to this, and a liquid material in which these are uniformly dispersed and mixed is added. There is a need to.

  In the embodiment shown here, PTFE (polytetrafluoroethylene) particles are adopted as the fluororesin, and the trade name: Alfa Aesar 44184, which is particles having an average diameter of about 5 μm, was used. Fluorine resin dispersants (approximately 90% of the total coating solvent) include flame retardant and non-hazardous methyl nonafluoroisobutyl ether (CAS.NO 163702-08-7) and methyl nonafluorobutyl ether (CAS.NO 163702-07-6) and the like are employed, and in this embodiment, HFE-7100, trade name: Sumitomo 3M Limited, is employed. As a polymer that fixes this dispersant and fluororesin as a base, it has a methyl group characterized by water repellency and weather resistance, and the terminal of the constituent molecule is blocked with an alkoxysilyl group (hydrolyzable). A methyl silicone alkoxy oligomer (alkoxysilane, alkoxysiloxane, etc.), which is an inorganic polymer, was used. In addition, by using a methyl silicone alkoxy oligomer and a small amount of a curing accelerator, it quickly cures with moisture in the air at room temperature, so that it can be easily sprayed in a one-pack type. Therefore, in this embodiment, a binder containing a curing accelerator (about 10% of the total paint solvent, which may contain impurities such as organic solvent of about 10% or less) is used. Chemical Industry Co., Ltd. X-40-2327) was adopted. By adopting such a combination, about 99% of the paint solvent does not place a burden on the environment and can prevent health damage to living things. By properly blending all of these, a super-water-repellent surface-emitting sensor paint with improved safety, with waterproof, moisture resistance, anti-icing, snow-proofing, oil resistance, chemical resistance, insulation, and weather resistance. Could get.

  As an example of a surface sensor, an experiment was conducted to confirm the performance by making a prototype of a super water-repellent PSP. PtTFPP (platinum porphyrin) is used as the luminescent dye, PTFE (polytetrafluoroethylene) particles have an average diameter of 5 μm, and the above-mentioned substances (product example: Sumitomo 3M Corporation HFE-7100) are cured as the dispersant. The binder containing the agent was combined using the aforementioned Shin-Etsu Chemical Co., Ltd. X-40-2327, and the respective compounding ratios were 2.3 mg, 22.0 g, 20.0 ml, and 2.1 ml. In order to confirm the superhydrophobicity of the present invention, TLC-PSP using a TLC plate having the same surface shape was prepared, and a state in which water droplets (2 ml) were respectively dropped was shown in FIG. The right side is a conventional TLC-PSP, and the upper part is an image from the horizontal direction and the lower part is an image from information, but it can be seen that the dropped water droplets are spread and absorbed on the sensor surface and wet the surface. The left side is an example of the present invention, and it can be seen that the dropped water droplets are superbly spherically placed on the surface, and the super-water-repellent PSP is playing water violently. It is recognized that there is no moisture adsorption on this painted surface.

The relationship between the light emission intensity and pressure of the pressure-sensitive paint, which utilizes the phenomenon that the light emission of the dye is quenched by oxygen, is expressed by the following stambolmer formula.
Here, A and B are calibration coefficients, I is the emission intensity from the PSP, P is the pressure value, T is the temperature, and ref is the value in the reference state (atmospheric pressure). The standardized emission intensity is expressed as Iref / I, and the calibration factor is a function of temperature. FIG. 2 shows the pressure sensitivity characteristics. The left graph shows the pressure-luminescence characteristics of the super-water-repellent PSP sensor according to the present invention. The horizontal axis represents the emission spectrum, and the vertical axis represents the standardized emission intensity as Iref / I. It has been. The measured values at 5 kPa, 10 kPa, 20 kPa, 40 kPa, 60 kPa, and 80 kPa are shown. The higher the atmospheric pressure, the higher the oxygen concentration in the air, so the extinction phenomenon increases and the emission intensity decreases. The graph on the right shows the pressure-luminescence characteristic comparison between the super-water-repellent PSP according to the present invention and the TLC-PSP sensor at a temperature of 25 ° C. and a humidity of 0%. Although all show linear characteristics, the sensitivity (inclination angle) is different. The TLC-PSP sensor has a value of 0.8 [% kPa], whereas the super-water-repellent PSP has a value of 0.9 [% kPa]. Incidentally, the characteristic of a conventional general PSP sensor is 0.6 [% kPa]. In addition, since it is a measured value in the state of humidity 0%, the influence by humidity does not appear in this data.

  Next, measurement was performed by taking a light emission image of the surface sensor with an experimental apparatus as shown in FIG. A surface sensor is installed on the sample stage, and a nitrogen gas injection nozzle having a diameter of 1 mm is installed in a direction parallel to the surface. A light source for irradiating the surface sensor with excitation light and an 8-bit high-speed camera for imaging the light emission state of the surface sensor are arranged. A high-pressure nitrogen gas of 1 kPa is injected from the injection nozzle. When the airflow flows in the vicinity of the surface sensor, the static pressure in the region decreases according to the flow speed. As a result, the pressure-sensitive surface sensor changes the emission intensity, and the image shows the pressure distribution on the surface sensor. The humidity in the chamber in which the surface sensor was arranged was measured by switching between 20% and 80%. First, a reference emission intensity distribution image is captured and stored in a state where there is no flow when the humidity is 20%. Subsequently, a reference emission intensity distribution image in a state where nitrogen gas is injected is captured and stored. Next, a reference luminescence intensity distribution image is captured and stored in a state where there is no flow when the humidity is 80%, and then a reference luminescence intensity distribution image in a state where nitrogen gas is injected is captured and stored. This image acquisition was performed for the super water-repellent PSP and TLC-PSP sensor according to the present invention. The camera settings in this experiment were a frame rate of 2,500 fps, an exposure time of 324.0 μS, and an optical filter having a bandpass bandwidth of 650 ± 50 nm.

  The four images shown in FIG. 4 are those of the super-water-repellent PSP according to the present invention on the left side, those of the TLC-PSP sensor on the right side, and an upper image when the humidity is 20%, and a lower image when the humidity is 80%. Is. The image of the super water-repellent PSP according to the present invention on the left side is clear when the humidity is 20% and when the humidity is 80%. Since the static pressure in the central portion where the flow is fast becomes low and the air flow injected from the nozzle diffuses toward the downstream, the pressure gradient should be reduced and spread. The state is clearly shown in both images. It can be said that the image of the right TLC-PSP sensor represents the pressure distribution although the image at the upper stage of humidity 20% is slightly blurred. However, it is clear that the image at 80% humidity does not correspond to the pressure distribution. This indicates that pressure measurement is not possible under high humidity conditions.

  FIG. 5 is a graph comparing the emission intensity ratio (Iref / I) of the super water-repellent PSP and the TLC-PSP sensor according to the present invention. The left side is the data of the super water-repellent PSP according to the present invention, and the right side is the data of the TLC-PSP sensor. All are one-dimensional pressure distributions in the region indicated by AB in FIG. 4, but this region corresponds to the same position with respect to the injection nozzle, and therefore the pressure distribution is assumed to be the same. Is done. Looking at the data of the super water-repellent PSP according to the present invention on the left side, the light emission intensity at a humidity of 20 ° C. and the light emission intensity at a humidity of 80% are superbly overlapped. Can be confirmed. Looking at the data of the TLC-PSP sensor on the right, the emission intensity at a humidity of 20 ° C. and the emission intensity at a humidity of 80% are greatly different, and the emission intensity at a humidity of 80% is high in the vicinity of both ends. This indicates that there is a peak, and it can be confirmed that it is significantly different from the actual pressure distribution. From these data, it has been demonstrated that the super water-repellent PSP according to the present invention can provide a surface emitting sensor having a moisture resistance function as a measurement surface and improving the responsiveness of the surface emitting sensor.

  In the present specification, the super water-repellent surface emitting sensor according to the present invention has been described using PSP as an embodiment, but the reason why the present invention has improved the super water repellency and sensitivity characteristics is not the luminescent dye. , A porous surface shape is formed by containing fluororesin particles such as PTFE, and by using a methyl silicone alkoxy oligomer as its binder, super water repellency, waterproof, moisture resistance, anti-icing, snow-proof, oil-resistant, Since the chemical resistance, weather resistance, and insulating functions are improved, the invention is also effective for other surface sensors such as temperature sensitive dyes and pH sensors.

1 Sample stage 2 Surface sensor 3 Light source 4 High-speed camera 5 Nozzle

Claims (8)

Aggregation between whole molecules having fluororesin particles with a diameter of several tens of μm or less for generating a porous surface shape as a main component, and a small amount of luminescent paint, and a methyl group as a binder for fixing it on the base A super-water-repellent surface-emitting sensor that is applied to a base made of a mixture of a small amount of methyl silicone with low strength.   The super water-repellent surface-emitting sensor according to claim 1, wherein PTFE particles are used as the fluororesin.   The super water-repellent surface-emitting sensor according to claim 1, wherein an alkoxy oligomer is used for the methyl silicone.   The super-water-repellent surface-emitting sensor according to any one of claims 1 to 3, wherein methyl nonafluoroisobutyl ether or methyl nonafluorobutyl ether is used as a dispersant for the light-emitting paint.   The super-water-repellent surface-emitting sensor according to any one of claims 1 to 4, wherein a moisture-curable silicone oligomer is used in the light-emitting coating material as a curing accelerator for promoting curing after coating.   The super-water-repellent surface-emitting sensor according to any one of claims 1 to 5, which is used for pressure measurement by using a chemical substance having an oxygen quenching function as a luminescent dye of the luminescent paint.   The super-water-repellent surface-emitting sensor according to any one of claims 1 to 5, which is used for temperature measurement by using a chemical substance having a thermal quenching function as a luminescent dye of the luminescent paint.   The super water-repellent surface-emitting sensor according to any one of claims 1 to 5, which is used for pH measurement by using a chemical substance having pH dependency as a luminescent dye of the luminescent paint.