JP4792568B2 - Temperature sensor and temperature sensitive paint - Google Patents

Description

  The present invention relates to a temperature sensor and a temperature-sensitive paint, and more particularly, to a temperature sensor and a temperature-sensitive paint that have high temperature sensitivity and extremely low pressure sensitivity and are excellent in durability against excitation light.

For example, in the aerospace field, measurement of the surface temperature field of an airframe is expected as an effective means for understanding a hydrodynamic phenomenon caused by a transition phenomenon of a flow field. Aircraft flight performance is highly dependent on the characteristics of the flow over the wing surface. Laminar flow and turbulent flow are mixed on the blade surface, and when turbulent flow becomes dominant (the flow is separated from the blade), the lift becomes small and eventually stalls (stall). By the way, since the heat transfer coefficient differs depending on whether the flow is turbulent or laminar, it is possible to evaluate the transition pattern of transition from laminar flow to turbulent flow by measuring the temperature distribution on the blade.
In recent years, measurement of a temperature field using temperature-sensitive paint (Temperature-Sensitive Paint: TSP) has attracted attention in wind tunnel experiments in the aerospace field. This measurement utilizes the phenomenon that the light emission of the pigment contained in the temperature-sensitive paint is quenched by thermal deactivation. The dye emits light when the excitation light is irradiated to the temperature-sensitive paint applied to the model surface of the aircraft. The emission intensity has a correlation with temperature, and the temperature field can be obtained by measuring the emission intensity distribution on the model with a CCD camera. As temperature-sensitive paints, temperature-sensitive paints using a chemical substance such as EuTTA or Ru (phen) as a temperature-sensitive dye are known (see, for example, Patent Document 1).
While the temperature field measurement by this thermosensitive paint is expected as an effective means to understand the hydrodynamic phenomenon caused by the transition phenomenon of the flow field, the temperature by the infrared (IR) camera is known as the conventional technology. Although field measurement is performed, the material of the wind tunnel observation window that can be measured with an IR camera is limited, and it cannot be measured with a glass material that is generally used. In addition, since it is strongly influenced by the surrounding temperature field environment other than the model, it is necessary to pay attention to the reflection of the background temperature field, and there is a problem that the setting is troublesome. In that respect, in the measurement using the temperature-sensitive paint, there is no problem of the IR camera as described above, and it can be said that this is a more practical measurement method.

JP 2004-35896 A

As mentioned above, chemical substances such as EuTTA and Ru (phen) are generally used as thermosensitive dyes, but these thermosensitive dyes have a problem that they have a slight pressure sensitivity although they have high temperature sensitivity. Yes. That is, since pressure distribution is generated on the surface of the wind tunnel model placed in a high-speed airflow, there is a problem that measurement errors due to pressure sensitivity are included when measuring with a conventional temperature-sensitive paint. Therefore, in order to improve the measurement accuracy, a pressure sensitivity lower than that of the conventional temperature sensitive paint is required. Further, these conventional thermosensitive dyes have a problem that they are susceptible to photodegradation. In practical experiments, since temperature sensitive paints are used for a long time, development of temperature sensitive paints that are resistant to light degradation is desired.
Therefore, the present invention has been made in view of the above circumstances, and provides a temperature sensor and a temperature-sensitive paint that have high temperature sensitivity, extremely low pressure sensitivity, and excellent durability against excitation light. With the goal.

In order to achieve the above object, the temperature-sensitive sensor of the present invention is characterized in that the temperature-sensitive sensitivity part is composed of a europium multinuclear complex compound having europium as a central metal and having excellent emission intensity.
As a result of extensive research by the inventor of the present application, by controlling the structure of the rare earth europium Eu (III) complex molecule, the temperature sensitivity is improved and the pressure sensitivity is improved compared to a conventional temperature sensor using a rare earth complex compound as a thermosensitive dye. It has been found that suppression, temperature field measurement by excitation with visible light, and improvement in durability against excitation light can be realized, and the present invention has been achieved.
Therefore, in the above-described temperature-sensitive sensor of the present invention, the molecular structure of a multinuclear complex using europium as a central metal is used as the sensitivity part that reacts to temperature, so that the emission intensity with respect to temperature is excellent, and as a result, the temperature sensitivity is excellent. did.

In the temperature sensitive sensor of the first invention, the europium polynuclear complex compound is represented by a chemical formula [Eu ₄ (μ-O) (L1) ₁₀ ], wherein L1 is 2-hydroxy-4-octyloxybenzophenone (2-hydroxy). -4-octyloxybenzophenone).
In general, an important factor for temperature sensitivity is a correlation of excitation energy levels between an organic ligand and a rare earth ion, europium Eu (III) ion. In this case, if the energy difference between the triplet level of the organic ligand and the emission level ( ⁵ D ₀ ) of the europium Eu (III) ion is 1500 cm ⁻¹ or less, the temperature dependence generally increases. It is considered. Therefore, a 2-hydroxybenzophenone derivative was employed as the ligand of the polynuclear complex compound. In addition, as a result of intensive research by the inventor of the present application, by introducing an organic ligand having a long-chain alkyl group into the polynuclear complex structure as an organic ligand and assembling it, oxygen molecules that cause pressure sensitivity and Found to reduce the interaction. Furthermore, in the fluorescence detection by visible light excitation, it is necessary to design the molecule so that the absorption of the polynuclear complex molecule is located on the longer wavelength side than 400 nm. However, the two-hydroxybenzophenone derivative and the rare earth ion Eu (III) ion This was made possible by extending the conjugated system of the ligand moiety by complex formation. As a result, the excitation light is effectively converted into the emission energy of Eu (III) ions, so that it is resistant to photodegradation.
Therefore, in the temperature sensor of the first invention, pressure sensitivity is suitable while maintaining high temperature sensitivity by using 2-hydroxy-4-octyloxybenzophenone as an organic ligand. The durability against excitation light is further increased.

In the temperature sensitive sensor of the second invention, the europium polynuclear complex compound is represented by a chemical formula m [Eu ₄ (μ-O) (L2) ₁₀ ], wherein L2 is 2hydroxy-4dodecyloxybenzophenone (2 -hydroxy-4-dodecyloxybenzophenone).
In the temperature sensor of the second invention, from the same design concept as the first invention, by using 2-hydroxy-4-dodecyloxybenzophenone as an organic ligand, While maintaining high temperature sensitivity, pressure sensitivity is suitably suppressed, and durability against excitation light is further increased.

In order to achieve the object, the temperature-sensitive paint of the third invention is a paint obtained by mixing a polymer with the polynuclear complex compound having the above-described structure, and fixing the paint to the object surface, thereby measuring the temperature field on the object surface. It is possible to make it possible.
In the temperature-sensitive paint of the third aspect of the invention, since it is adapted to the surface of any object by adopting the form of paint, the surface temperature field of the object can be measured without depending on the surface shape of the object. It becomes.

According to the temperature sensor of the present invention, since it has characteristics of higher temperature sensitivity and extremely lower pressure sensitivity than conventional temperature sensitive dyes (EuTTA and Ru (phen)), the surface temperature field of an object can be measured with high accuracy. It becomes possible. Moreover, since it has durability against light deterioration, it is suitable for practical wind tunnel experiments.
In addition, unlike the conventional rare earth complex compound, the temperature sensor of the present invention can be excited in the visible wavelength range, so that the measurement of the surface temperature field of the object does not depend on the material of the wind tunnel observation window. Furthermore, since a light source in the visible light region is used as an excitation light source for the temperature sensor, the experimenter does not damage the eyes with ultraviolet light.
In addition, since the europium polynuclear complex compound according to the present invention belongs to the rare earth complex compound, it is easy to change the emission wavelength by exchanging the central metal. For example, the emission color can be changed from red to green by replacing europium Eu with terbium Tb. Therefore, by selecting an appropriate wavelength range, it is possible to make a composite with a pressure sensitive paint. As a result, if a composite coating is made, the pressure and temperature fields can be measured simultaneously.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.

FIG. 1 is an explanatory diagram showing an example of a molecular structure when the europium Eu multinuclear complex compound constituting the temperature sensitive part of the temperature sensor of the present invention is a europium Eu tetranuclear complex compound.
The europium Eu tetranuclear complex compound 100 includes a central metal in which an oxo bridge structure is formed by four europium Eu (III) ions and one oxygen atom O, and a ligand L1 around the central metal, for example, It consists of 10 2-hydroxy-4-octyloxybenzophenone having the following structural formula.

  The temperature sensor of the present invention in which the temperature sensitivity portion is composed of the europium Eu tetranuclear complex compound 100 will be described in detail later with reference to FIG. 3, but corresponds to the temperature of the object to be measured in the visible light excitation state. It has a characteristic of emitting sharp light with a narrow band width having emission intensity, so-called peak light. It should be noted that it has higher temperature sensitivity characteristics than the conventional temperature sensor in which the sensitivity part is composed of temperature sensitive dyes such as Eu (TTA) and Ru (phen), and these conventional temperature sensors Compared with extremely low pressure sensitivity characteristics. Therefore, the present invention can be suitably applied to an aircraft wind tunnel experiment in which the pressure varies, and the temperature field of the object to be measured can be measured with high accuracy.

  Further, since the wavelength range of the peak light emitted as the output of the temperature sensor of the present invention is also in the visible light range, for example, as a wind tunnel observation window through which excitation light or peak light is transmitted, a versatile material such as BK7 (SCHOTT It is possible to use the glass material of GLAS. Furthermore, since the wavelength range of the excitation light and the fluorescence is in the visible light range, it is preferable that the experimenter does not damage the eye with the excitation light.

  The ligand L1 has a photosensitizing function. Here, the “photosensitization function” is a function of efficiently transferring irradiated light energy (in this embodiment, light energy of excitation light) to europium Eu (III) ions. With this function, europium Eu (III) ions absorb light energy of excitation light and are preferably excited to emit light.

  Moreover, since the said ligand L1 has a long-chain alkyl group, it has the pressure sensitivity suppression function of reducing the interaction of the oxygen molecule and europium Eu tetranuclear complex which become a generation factor of pressure sensitivity. Furthermore, in the detection of luminescence by excitation with visible light, it is necessary to design the complex molecule so that the absorption of the complex molecule occurs on the longer wavelength side than 400 nm. Europium Eu (III) which is a 2-hydroxybenzophenone derivative and a rare earth ion By forming a complex with ions, the conjugated system of the ligand portion is extended, and the complex molecule can be absorbed on the long wavelength side. As a result, since the excitation light is effectively converted into the emission energy of europium Eu (III) ions, the europium Eu tetranuclear complex compound becomes strong against photodegradation.

FIG. 2 is an explanatory view showing another example of the molecular structure when the europium Eu multinuclear complex compound constituting the temperature sensitive part of the temperature sensor of the present invention is a europium Eu tetranuclear complex compound.
The europium Eu tetranuclear complex compound 200 includes a central metal in which an oxo bridge structure is formed by four europium Eu (III) ions and one oxygen atom O, and a ligand L2 around the central metal, for example, It consists of 10 2-hydroxy-4-dodecyloxybenzophenone having the following structural formula.

  The europium tetranuclear complex compound 200 has the same molecular structure as the europium Eu tetranuclear complex compound 100 except for the ligand L2. The ligand L2 of the europium tetranuclear complex compound 200 also has a photosensitization function and a pressure sensitivity suppression function.

In general, the ligand of the europium tetranuclear complex compound is preferably a compound having benzophenone or benzoyl as a basic skeleton and having a triplet π-π ^* state.

次に、上記物質を混合して溶液にした後、スプレーガンを用いて後述の基板に塗装することにより感温塗料の試験用サンプルを作製した。なお、発光強度を増大させるため、アルミ板に白色ベースコートを塗装した基板の上に感温塗料ＴＳＰ１,ＴＳＰ２を塗布した。 A manufacturing example of the temperature-sensitive paints TSP1 and TSP2 as one embodiment of the temperature-sensitive sensor of the present invention will be shown below.
First, dichloromethane was used as a solvent, and PMMA (polymethyl methacrylate) was used as a polymer. Then, Europium Eu tetranuclear complex compounds 100 and 200 shown in the table below were mixed as pigments with 10 ml of dichloromethane and 0.5 g of PMMA. M.W represents molecular weight.

Next, after mixing the said substance to make a solution, it applied to the below-mentioned board | substrate using the spray gun, and the sample for a test of a thermosensitive paint was produced. In order to increase the emission intensity, the temperature sensitive paints TSP1 and TSP2 were applied on a substrate obtained by painting a white base coat on an aluminum plate.

FIG. 3 is a graph showing excitation / fluorescence characteristics of the temperature-sensitive paints TSP1 and TSP2. 3A shows the excitation / fluorescence characteristics of the temperature-sensitive paint TSP1, and FIG. 3B shows the excitation / fluorescence characteristics of the temperature-sensitive paint TSP2. Note that the measurement was performed under a room temperature and atmospheric pressure environment.
The excitation wavelength of the temperature sensitive paint TSP1 was about 410 nm, and the fluorescence wavelength was about 615 nm. On the other hand, in the temperature sensitive paint TSP2, the excitation wavelength was about 410 nm and the fluorescence wavelength was about 615 nm. In other words, regarding the wavelength, these europium Eu tetranuclear complex compounds 100 and 200 show almost the same characteristics, and the conventional rare earth complexes are excited by ultraviolet light (<350 nm), but both are excited in the visible light region, and visible light. Emits fluorescent light. Note that the peak at 615 nm in FIGS. 3A and 3B is based on the transition of ⁵ D ₀ → ⁷ F ₂ of the europium Eu (III) ion.

FIG. 4 is an explanatory diagram showing a temperature-sensitive paint calibration test system 10.
The temperature-sensitive paint calibration test system 10 includes a personal computer 1 as a measuring device, a xenon light source 2 that generates excitation light that excites the temperature-sensitive paint, a CCD camera 3 that receives fluorescence emitted from the temperature-sensitive paint, A vacuum chamber 4 for storing the temperature-sensitive paint test samples TSP1, TSP2, a temperature controller 5 for controlling the temperature of the substrate 41 coated with the test samples TSP1, TSP2, and a pressure for controlling the pressure in the vacuum chamber 4 And a controller 6. An excitation filter 21 is provided on the front surface of the excitation light head, and a light emission filter 31 is provided on the front surface of the CCD camera. Moreover, since the excitation spectrum and fluorescence spectrum of the temperature sensitive paints TSP1 and TSP2 have a peak on the long wavelength side, BK7 (trade name of SCHOTT GLAS) is used as the glass material of the observation window 42 of the vacuum chamber 4. can do.

FIG. 5 is a graph showing temperature sensitivity characteristics of the temperature-sensitive paint. The horizontal axis indicates the temperature of the substrate 41, and the vertical axis indicates the fluorescence intensity. Further, the fluorescence intensity is made dimensionless by taking a ratio with respect to the reference fluorescence intensity I _ref . As a comparative example, the temperature sensitivity characteristics of a temperature-sensitive paint using a conventional ruthenium complex compound Ru (phen) as a pigment are also shown. The internal pressure of the vacuum chamber 4 was maintained at 100 [kPa] by the pressure controller 6.
From this graph, the temperature sensitivity of the temperature-sensitive paint TSP1 and temperature-sensitive paint TSP2 is about 2.5% / ° C in the temperature range of 10 to 40 ° C. On the other hand, the temperature sensitivity of the conventional temperature-sensitive paint using Ru (phen) as a pigment was about 1.7% / ° C. in the same temperature range. From this result, it can be seen that the thermosensitive paints TSP1 and TSP2 of the present invention have a temperature sensitivity about 1.5 times that of the conventional thermosensitive dye.

FIG. 6 is a graph showing the pressure sensitivity characteristic of the temperature-sensitive paint. The horizontal axis indicates the internal pressure of the vacuum chamber 4, and the vertical axis indicates the inverse ratio of the fluorescence intensity to the reference intensity _Iref . As a comparative example, the sensitivity characteristics of a temperature-sensitive paint using a conventional ruthenium complex compound Ru (phen) as a pigment are also shown. The temperature of the substrate 41 was maintained at 50 ° C. by the temperature controller 5.
From this graph, the pressure sensitivity of the temperature-sensitive paint TSP1 and the temperature-sensitive paint TSP2 is almost zero in the pressure range of 0 to 100 [kPa], whereas the conventional ruthenium complex compound Ru (phen) The pressure sensitivity of the temperature-sensitive paint used as the dye was about 10% / 100 [kPa] in the same pressure range. From this result, it can be seen that the temperature-sensitive paints TSP1 and TSP2 of the present invention have extremely low pressure sensitivity compared to conventional temperature-sensitive dyes. This is because the conventional Ru (phen) complex exhibits oxygen concentration dependence, and the thermosensitive paint of the present invention is assembled by introducing an organic ligand having a long-chain alkyl group into a multinuclear complex structure. This is because it has a molecular structure that reduces the interaction with oxygen molecules that cause pressure sensitivity. Thereby, for example, it becomes possible to accurately measure the temperature field of the blade surface where the pressure of the air flow fluctuates.

FIG. 7 is a graph showing deterioration characteristics of the temperature-sensitive paint. The horizontal axis indicates the elapsed time, and the vertical axis indicates the ratio of the light intensity to the light intensity at t = 0 [min] as a change in the light emission intensity. In addition, as a comparative example, deterioration characteristics of a temperature-sensitive paint using a conventional ruthenium complex compound Ru (phen) as a pigment are also shown. The temperature of the substrate 41 was maintained at 20 ° C. by the temperature controller 5, and the internal pressure of the vacuum chamber 4 was maintained at 100 [kPa] by the pressure controller 6.
Here, the “deterioration characteristics” are the results of evaluating the rate at which the thermosensitive dye is destroyed by the excitation light and the emission intensity is attenuated. Therefore, the higher the decay rate of the emission intensity, that is, the greater the downward slope of the graph, the easier it is to deteriorate. In the experiment, excitation light from the xenon light source 2 was applied to the substrate 41 coated with the temperature-sensitive paint, the change in emission intensity was measured by the CCD camera 3, and the change in emission intensity was calculated by the personal computer 1.

  From the results of this graph, the temperature-sensitive paint using the ruthenium complex compound Ru (phen) as a pigment deteriorates the light emission intensity over time, whereas the temperature-sensitive paints TSP1 and TSP2 of the present invention have the time The light emission intensity hardly deteriorates with the passage of time, and is durable against light deterioration and can be said to be a practical temperature sensor.

  According to the temperature sensitive paint which is one embodiment of the temperature sensor of the present invention, it has a high temperature sensitivity characteristic and a very low pressure sensitivity characteristic. Can be measured with high accuracy. In addition, in the conventional temperature-sensitive paint, a special glass material that transmits ultraviolet rays to the laboratory window had to be used for excitation of ultraviolet rays. Because of fluorescence, it is possible to use a versatile glass material that transmits visible light, and the equipment cost can be reduced. Furthermore, the temperature-sensitive paint of the present invention is durable against light deterioration, has a sufficiently bright emission intensity, and is suitable as a temperature sensor.

In the europium Eu tetranuclear complex compound, europium ion Eu ³⁺ is used as the rare earth ion, but other rare earth ions such as terbium ion Tb ³⁺ , cerium ion Ce ³⁺ , neodymium are used instead of europium ion Eu ^3+. It is also possible to obtain a binuclear rare earth complex compound using ions Nd ³⁺ , samarium ions Sm ³⁺ , erbium Er ^3+, ytterbium Yb ^{3+, and the} like. It is also possible to use a binuclear rare earth complex compound composed of the same kind or different kind of rare earth ions other than the tetranuclear.

In this case, the emission wavelength of the thermosensitive paint can be changed by substituting europium ions with other rare earth ions. For example, the emission wavelength can be changed from red to green by replacing europium ion Eu ³⁺ with terbium ion Tb ³⁺ .

  Therefore, by selecting an appropriate wavelength range, it is possible to make a composite with a pressure sensitive paint. As a result, if a composite coating is realized, the pressure and temperature fields can be measured simultaneously.

  The temperature sensor and the temperature-sensitive paint of the present invention can be applied not only to the measurement of the temperature field of the model surface in the wind tunnel experiment, but also to the measurement of the liquid temperature monitor and the surface temperature field of the micro object.

It is explanatory drawing which shows an example of the molecular structure in case the europium Eu polynuclear complex compound which comprises the temperature sensitivity part of the temperature sensor of this invention is a europium Eu tetranuclear complex compound. It is explanatory drawing which shows the other example of the molecular structure in case the europium Eu polynuclear complex compound which comprises the temperature sensitivity part of the temperature sensor of this invention is a europium Eu tetranuclear complex compound. It is a graph which shows the excitation / fluorescence characteristic of a temperature sensitive coating material. It is explanatory drawing which shows the calibration test system of a temperature-sensitive paint. It is a graph which shows the temperature sensitivity characteristic of a temperature sensitive coating material. It is a graph which shows the pressure sensitivity characteristic of a temperature sensitive coating material. It is a graph which shows the deterioration characteristic of a temperature sensitive coating material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Personal computer 2 Xenon light source 3 CCD camera 4 Vacuum chamber 5 Temperature controller 6 Pressure controller 10 Calibration test system of thermosensitive paint 100,200 Europium Eu tetranuclear complex

Claims (3)

The temperature sensitive sensor is a temperature sensitive sensor composed of a europium multinuclear complex compound having excellent emission intensity with europium as a central metal ,
The europium polynuclear complex compound is represented by the chemical formula [Eu ₄ (μ-O) (L1) ₁₀ ], wherein L1 is 2-hydroxy-4-octyloxybenzophenone. A temperature sensor. The temperature sensitive sensor is a temperature sensitive sensor composed of a europium multinuclear complex compound having excellent emission intensity with europium as a central metal,
The europium polynuclear complex compound is represented by the chemical formula m [Eu ₄ (μ-O) (L2) ₁₀ ], wherein L2 is 2-hydroxy-4-dodecyloxybenzophenone. temperature-sensitive sensor according to claim. 3. A temperature-sensitive paint characterized in that the polynuclear complex compound according to claim 1 or 2 is mixed with a polymer to form a paint, and the paint is fixed to the surface of the object so that the temperature field of the object surface can be measured. .

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