Temperature indicating material and temperature sensing system

Abstract

To provide a member and system, which can be easily installed at a measurement point without accompanying wiring and enable highly accurate surface temperature measurement in a high temperature range.SOLUTION: A member provided herein has a selective reflection wavelength range, where a peak wavelength changes at a rate of 1 nm / °C or greater, at 100°C or higher.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a material whose color changes in correlation with temperature, and to temperature sensing using the same. [Background technology]

[0002] In industrial manufacturing processes, food cooking and heating processes, etc., it is necessary to precisely measure the temperature of heating components and heated objects to ensure high quality. In particular, in semiconductor manufacturing processes, where high quality must be guaranteed, it is necessary to measure with an accuracy of 1°C or less in the high temperature range of 100 to 200°C, and in some cases 200 to 300°C or higher.

[0003] Generally, when measuring temperature, it is often done using elements such as thermocouples and thermistors that change electrically with temperature. In this case, it is necessary to introduce power and wiring between the external control device, which makes it difficult to introduce it into the device or the place to be measured. In addition, when trying to measure the surface temperature distribution using the above elements, multiple elements are arranged on the surface, or measurements are made using a sensor that has been arranged in advance, but since each of the above elements is large, it is difficult to increase the resolution. In addition, when multiple elements are laid out on a plane, the amount of wiring required increases, making wiring and handling even more complicated.

[0004] On the other hand, there are also examples of devices that do not require external power, which use materials that change color in response to temperature. These include leuco dyes, whose molecular structure changes with temperature, and materials such as wax that change color through phase changes when melted, but due to their characteristic of gradually changing with heating, the resolution of the temperature that can be measured is low.

[0005] Another example of a material whose color changes in response to temperature is cholesteric liquid crystal. The color changes as the pitch of the cholesteric liquid crystal changes in response to temperature, and because it has good temperature tracking properties, it has a color and reflection spectrum that uniquely corresponds to temperature. However, in the past, cholesteric liquid crystals were used mainly for applications such as displays, with the main focus being on not changing with temperature, and the usage environment was assumed to be room temperature or room temperature + 20 to 60°C (Patent Document 1), so there was no idea of ​​using it for temperature sensing with high resolution, especially in the high temperature range, and no examples of actual consideration of using it. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-125741 A Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional examples, there has been a lack of consideration given to sensing temperature, particularly surface temperature, with high accuracy using materials whose color changes with temperature, and specific aspects for achieving this have not been disclosed.

[0008] An object of the present invention is to provide a component and a system for measuring temperature without using external power or wiring, and for measuring surface temperature with high accuracy, particularly in high temperature regions. [Means for solving the problem]

[0009] In order to solve this problem, the present invention has the following configuration. [1] A component that has a selective reflection wavelength range at 100°C or higher, and the peak wavelength in the reflection wavelength range changes by 1 nm / °C or more. [2] The component according to [1], comprising a liquid crystal material. [3] The member according to [2], wherein the phase transition temperature of the liquid crystal material to an isotropic liquid is 200°C or higher. [4] The member according to [2] or [3], wherein the liquid crystal member has a polymerizable group. [5] The member according to any one of [2] to [4], wherein the liquid crystal material has cholesteric liquid crystallinity. [6] The component according to [5], which comprises one or more chiral agents. [7] The component according to [6], wherein the rate of change of the helical twisting power (HTP) of the chiral agent with respect to temperature is 0.15% / °C or more. [8] The member according to any one of [1] to [7], wherein the peak wavelength of the selective reflection wavelength is in the range of 200 nm or more and 1500 nm or less. [9] The member according to any one of [1] to [8], wherein the half-value width of the reflection spectrum at the selective reflection wavelength is 100 nm or less.

[10] The member according to any one of [2] to [9], wherein the liquid crystal material has a temperature range in which it exhibits a smectic A phase.

[11] The component according to

[10] , further comprising a chiral agent.

[12] The member according to any one of [1] to

[11] , which is polymerizable by heat.

[13] A material for measuring temperature, comprising the member according to any one of [1] to

[12] and a substrate.

[14] A temperature sensor comprising the member according to any one of [1] to

[13] , which identifies temperature by measuring a reflection spectrum.

[15] The member according to any one of [1] to

[13] , wherein the reflection spectrum changes in response to the temperature at a predetermined time, and the reflection spectrum does not change with temperature changes after the predetermined time.

[16] A temperature sensor comprising a component according to any one of [1] to

[13] and

[15] , the reflection spectrum of which changes in response to the temperature at a predetermined time, and which does not change with temperature changes after the predetermined time, the temperature sensor measures the reflection spectrum corresponding to the temperature at the predetermined time at a time after the predetermined time, and identifies the temperature at the predetermined time.

[17] A sensing system that identifies a surface temperature by measuring the reflectance spectrum of a temperature sensor such as

[14] or

[16] as an image. Effect of the Invention

[0010] According to the present invention, there is provided a new component and system that can sense surface temperatures with high accuracy in high temperature ranges and that can be easily installed at a measurement location because it does not require external power or wiring. [Brief description of the drawings]

[0011] [Figure 1] 1 shows a conceptual diagram of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The electrode of the present invention will be described in detail below.

[0013] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, the term "same" includes a margin of error generally accepted in the technical field.

[0014] Note that the drawings shown below are all conceptual diagrams for explaining the present invention, and therefore the shapes, thicknesses, sizes, positional relationships, etc. of the components do not necessarily correspond to the actual ones.

[0015] As a result of intensive research into the present invention, it has been discovered that by using a component that has a selective reflection wavelength spectrum at 100°C or higher and whose reflection wavelength spectrum peak changes by 1 nm or more with a temperature change of 1°C, it is possible to precisely measure temperatures in high-temperature regions, particularly surface temperatures, without the need for wiring (power) connected to the component. The high temperature range can be adjusted depending on the object to be measured. When a higher temperature range is measured, it is preferable that the change is 1 nm / °C or more at 150°C or higher, and it is preferable that the change is 1 nm / °C or more at 200°C or higher. By changing sharply with respect to temperature change, specifically by changing by 1 nm / °C or more, it is possible to identify the temperature with high accuracy, and by changing by preferably 2 nm / °C or more, more preferably 5 nm / °C or more, and even more preferably 10 nm / °C or more, it is possible to identify the temperature with high accuracy. The sharper the spectrum changes with respect to temperature, the greater the change in the reflection spectrum (color) with respect to temperature will be, for example, from the ultraviolet range to the visible range to the infrared range. Therefore, for example, when observing and identifying with the naked eye or with a visible camera, it is preferable to prepare multiple members so that the change can be observed in the visible range. When it is desired to measure with one or a few members, it is preferable to use a measurement system that can measure a wide wavelength range. There is no particular limitation on the upper limit, but if the change in the peak of the reflection spectrum is large, the wavelength range of the reflection spectrum is likely to span multiple regions, such as ultraviolet, visible, near infrared, and far infrared, and the measurement means for the reflection spectrum (color) may become very complicated. Alternatively, if the measurement means is limited to the visible range, the measurable temperature range may become extremely narrow. Therefore, it is preferable that the peak of the reflection wavelength spectrum change by 300 nm or less with a temperature change of 1° C., and it is more preferable that it change by 100 nm or less.

[0016] As a method for identifying the temperature from the color of the temperature indicator, the color of the temperature indicator at each temperature is recorded in advance, and the color that appears corresponding to each temperature during actual measurement can be identified by comparing the records. It is also preferable to record the color of each temperature recorded in advance as a reflection spectrum, convert it into data as a calibration curve of peak wavelength, chromaticity, etc. versus temperature, and analyze the data during actual measurement in order to improve accuracy. The reflection spectrum and color may be measured by the same method for pre-recording and actual measurement, or the means for pre-recording and actual measurement may be different as long as the data can be converted. In the member of the present invention, the temperature range in which the reflection spectrum (color) changes is preferably defined as a range having a unique reflection spectrum for each temperature in order to measure the temperature. If the width of the defined temperature range (the difference between the defined lower limit temperature and the upper limit temperature at which the reflection spectrum (color) is observed to change with temperature) is wide, it is preferable because a wide range of temperatures can be measured with one member, but the wider the temperature range, the greater the change in the reflection spectrum (color), so the measurement means may be limited. The width of the temperature range (the difference between the defined lower limit temperature and the upper limit temperature at which the reflection spectrum (color) of the reflectance changes with temperature) is preferably 1°C or more, more preferably 5°C or more, even more preferably 10°C or more, and even more preferably 50°C or more. As described above, it is preferable that the member of the present invention has a unique reflection spectrum for each temperature in a specified temperature range. For example, a temperature range in which the reflection range of the reflection spectrum shifts in one direction to longer waves with increasing temperature can be used, or a temperature range in which the reflection range of the reflection spectrum shifts in one direction to shorter waves with increasing temperature can be used. The rate of change of the top peak of the reflection spectrum can be calculated from the change width of the top peak of the reflection spectrum relative to the width of the specified temperature range. The width of the specified temperature range can be set arbitrarily from among the temperature ranges in which the color changes. The top peak refers to the wavelength value at which the reflectance is maximum in a reflection range (wavelength range with a reflection peak) in which the reflectance increases with respect to the baseline (reflectance in a wavelength range with no reflection peak).

[0017] In the member of the present invention, it is preferable that the member contains a liquid crystal material (a compound or material exhibiting liquid crystallinity), and it is preferable that the compound exhibits cholesteric liquid crystallinity. Compounds exhibiting liquid crystallinity (hereinafter also referred to as "liquid crystal compounds") are applied to various uses, for example, liquid crystal compounds are applied to the manufacture of optical anisotropic bodies represented by retardation films, or the manufacture of reflective films in which a cholesteric liquid crystal phase is fixed, and examples of such materials can also be referred to. The temperature can be identified by the characteristic of cholesteric liquid crystals that the pitch interval changes uniquely depending on the temperature. Cholesteric liquid crystallinity may be exhibited as a characteristic of the material itself, such as hydroxypropyl cellulose, or may be expressed by mixing a chiral agent with a liquid crystal material exhibiting nematic properties. In order to control heat resistance, temperature characteristics, and the band of the reflection spectrum, a system in which a chiral agent is used in combination is preferable.

[0018] Examples of materials that are preferably used in the present invention are shown below. In order to use at high temperatures, it is necessary that the temperature range from the transition point (phase transition temperature) exhibiting nematic properties to the iso point (transition point to isotropic phase, also called phase transition temperature) overlaps or is included in the temperature range to be measured. The transition point exhibiting nematic properties can change depending on the materials to be mixed, so it is necessary to control the above-mentioned mode taking into consideration not only the liquid crystal material but also the type and amount of the materials to be mixed. The phase transition temperatures of the smectic phase and the crystallized phase can be measured by the following method: Two polarizers of an optical microscope (Nikon ECLIPSE E600 POL) are arranged so as to be perpendicular to each other, a sample stage is set between the two polarizers, a small amount of the prepared polymerizable composition is placed on a slide glass, and the slide glass is set on a hot stage placed on the sample stage, and the state of the sample is observed under a microscope, and the sample is heated to a nematic phase, and then the upper limit temperature and crystallization temperature of the smectic phase (Sm) are measured while decreasing the temperature at 10°C / min, and the temperature range of the smectic phase (Sm) is calculated. The phase transition temperature of the isotropic phase can also be identified using a polarizing microscope. There are no particular limitations on the compound that exhibits liquid crystallinity over a wide temperature range, but for example, a material having a structure with strong interactions at the center (core) of the molecule (for example, a naphthalene skeleton having a side chain structure at the 1,4-positions as described in Japanese Patent Application No. 2019-068662) can be preferably used. In the case of this structure, it is considered that the stacking property between molecules is improved, so the upper limit temperature at which liquid crystallinity is exhibited is increased and the temperature range is widened.

[0019] As the liquid crystal material, liquid crystal compounds described in Japanese Patent Application No. 2019-177850, Japanese Patent Application No. 2019-530600, Japanese Patent Application No. 2019-068662, etc. are preferable. The composition ratio of the liquid crystal material is preferably 70% or more by weight, more preferably 80% or more, and particularly preferably 90% or more. There is no particular upper limit, but it is preferably less than 100%. As a property of the liquid crystal material, in order to exhibit cholesteric liquid crystallinity up to a higher temperature range within the scope of the present specification, the iso point is preferably 200° C. or higher, more preferably 250° C. or higher, and particularly preferably 300° C. or higher. From the same viewpoint, the crystallization temperature is preferably less than 100° C., and more preferably 80° C. or lower. The phase transition temperature was identified by observation with a polarizing microscope while heating. The liquid crystal material may contain a plurality of types. It is also preferable that the liquid crystal material contains a polymerizable group such as an acryloyl group, an epoxy group, an oxetane group, or the like as a terminal group. The retardation Δn of the liquid crystal material is preferably 0.01<Δn<0.15, more preferably 0.011<Δn<0.12, and further preferably 0.012<Δn<0.10.

[0020] There are no particular limitations on the chiral agent, but the chiral agents described in Japanese Patent Application No. 2001-005741, Japanese Patent Application No. 2001-246704, and Japanese Patent Application No. 2019-513701 can be preferably used. In general, a cholesteric liquid crystal phase is formed by adding a chiral compound to a nematic liquid crystal. The above-mentioned patent document discloses a polymerizable chiral compound having a binaphthyl skeleton as a polymerizable chiral compound having a strong helical twisting power (HTP). As a characteristic of the chiral material, the liquid crystallinity is increased when the material exhibits cholesteric properties in a small amount, so the weight percentage is preferably 30% or less, more preferably 20% or less, and particularly preferably 10% or less. There is no particular lower limit, but 1% or more is preferable. From the same viewpoint, the rate of change of HTP is preferably 0.15% / °C or more, more preferably 0.25% / °C or more, and more preferably 0.50% / °C or more. The chiral material may contain multiple types.

[0021] There is no particular limitation on the method for bringing about the temperature change defined in the present application, but for example, when a chiral agent is mixed into a nematic liquid crystal phase to express cholesteric liquid crystallinity, it is preferable to use a chiral agent whose structure is easily changed by temperature. For example, a compound represented by the following general formula (I) can be used.

[0022] [ka]

[0023] In the above formula, R represents a hydrogen atom, an alkoxy group having 1 to 15 carbon atoms, an acryloyloxyalkyloxy group having a total of 3 to 15 carbon atoms, or a methacryloyloxyalkyloxy group having a total of 4 to 15 carbon atoms. Examples of the alkoxy group having 1 to 15 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a hexyloxy group, an octyloxy group, and a dodecyloxy group. Among these, an alkoxy group having 1 to 10 carbon atoms is preferable, and an alkoxy group having 1 to 8 carbon atoms is particularly preferable.

[0024] Examples of the acryloyloxyalkyloxy group having a total of 3 to 15 carbon atoms include an acryloyloxy group, an acryloyloxyethyloxy group, an acryloyloxypropyloxy group, an acryloyloxyhexyloxy group, an acryloyloxybutyloxy group, and an acryloyloxydecyloxy group, among which, an acryloyloxyalkyloxy group having a carbon number of 3 to 13 is preferred, and an acryloyloxyalkyloxy group having a carbon number of 3 to 11 is particularly preferred. Examples of the methacryloyloxyalkyloxy group having a total of 4 to 15 carbon atoms include a methacryloyloxy group, a methacryloyloxyethyloxy group, and a methacryloyloxyhexyloxy group, among which, a methacryloyloxyalkyloxy group having a carbon number of 4 to 14 is preferred, and a methacryloyloxyalkyloxy group having a carbon number of 4 to 12 is particularly preferred. In addition, for example, materials described in JP-A-2003-55315 and JP-A-2018-1914157 can be preferably used.

[0025] Also, for example, by introducing a chiral agent into a liquid crystal material exhibiting a smectic A phase, the reflection spectrum can be changed steeply near the low temperature side of the nematic-smectic A phase transition point. Although the principle behind this is unclear, it is assumed that the pitch changes steeply when a crystalline material is mixed into the cholesteric phase. At this time, since the smectic A phase transition point changes depending on the amount of chiral material mixed, in order to realize the change specified in the present application in the desired temperature range and desired reflection spectrum peak, it is necessary to control the smectic A phase transition point of the liquid crystal material alone, and the type and amount of the chiral agent, taking into consideration that the more chiral material is introduced, the narrower the pitch of the cholesteric phase shifts to the short wavelength side, and the lower the smectic A phase transition point (the maximum temperature at which the transition changes steeply). In this case, the smectic A transition point is preferably 100° C. or higher in order to satisfy the content of the present specification, taking into consideration that the temperature range may decrease due to the influence of chiral materials, etc. In order to measure in a higher temperature range, the temperature is preferably 150° C. or higher, more preferably 200° C. or higher, and even more preferably 250° C.

[0026] When identifying temperature by color, it is preferable that the reflectance of the selective reflection wavelength range is larger than the baseline of the reflection spectrum (reflectance in a wavelength range with no reflection peak) because it is easier to identify the difference. The difference between the baseline of the reflection spectrum and the reflectance of the selective reflection wavelength range is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. Similarly, it is preferable that the band of the selective reflection wavelength (half-width of the reflection spectrum) is narrower because it is easier to identify the difference. The half-width of the reflection spectrum is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. The reflection spectrum can be measured by a normal total light reflectance measuring device having an integrating sphere. The selective reflection wavelength range is not particularly limited, but ultraviolet, visible, or infrared ranges are preferable because observation equipment is easily available and can be selected. As the selective reflection wavelength range, the top peak of the reflection spectrum is preferably 200 nm or more and 1500 nm or less, preferably 300 nm or more and 1100 nm or less, and more preferably 400 nm or more and 700 nm or less. The reflectance spectrum and the temperature dependence of the reflectance spectrum can be measured using a spectrophotometer equipped with a temperature variable stage.

[0027] The member specified in the present application may contain, in addition to the above liquid crystal material and chiral material, other materials such as a durability improving material, a heat conductive material, a plasticizer, a coloring material, etc. Also, instead of a single layer, it may be configured to have a plurality of liquid crystal layers or a plurality of layers such as other functional layers such as an abrasion-resistant layer, a barrier layer, a coloring layer, and an anti-reflection layer.

[0028] An example of a temperature measuring material using the member of the present invention is conceptually shown in Fig. 1. The temperature measuring material 10 shown in Fig. 1 has a substrate 12 and a temperature indicating member 14. The temperature indicating member is made of a member specified in the present application.

[0029] There is no particular restriction on the substrate 12, and it can be selected arbitrarily depending on the place, device, and temperature range to be measured. Glass, silicon, PET, and other films can be preferably used. A laminated material of multiple materials may also be used. In the case of measurement of semiconductor processes, etc., glass and silicon, which do not generate dust, are preferable. There is no particular restriction on the shape and thickness, but it is preferable to make them the same or similar in shape and thickness to the substrate used in the device to be temperature controlled. When measuring a part with curvature such as a roller, it is preferable to use a film-like flexible substrate. If the thickness is too thick, problems such as poor thermal conductivity and large heat capacity may occur, resulting in poor followability to the temperature of the measurement part, and the thickness is preferably 1000 μm or less, and preferably 500 μm or less. When flexibility is required, it is further preferable to make it 200 μm or less, and preferably 100 μm or less. There is no particular restriction on the lower limit of the thickness, but from the viewpoint of handleability, it is preferably 10 μm or more, and preferably 40 μm or more. The substrate 12 and the temperature indicating member 14 may be in direct contact with each other, or in order to make it easier to visually recognize the change in color, a colored layer (for example, a layer that absorbs light in the observation wavelength range) may be provided between the substrate 12 and the temperature indicating member 14. When the substrate 12 is transparent to the observation wavelength, the colored layer may be provided on the opposite side of the substrate 12 to the temperature indicating member 14. In addition, when a liquid crystal layer is used, a liquid crystal alignment layer may be provided on the temperature indicator 14 side of the substrate 12. There are no particular limitations on the liquid crystal alignment layer, but examples described in Japanese Patent Application No. 2019-513701, Japanese Patent Application No. 2019-068662, etc. can be preferably used.

[0030] As described above, the peak wavelength region, half width, and reflectance of the reflection spectrum of the temperature indicator 14 in FIG. 1 can be appropriately selected depending on the device and circumstances for measuring the temperature.

[0031] There is no particular limit to the thickness of the temperature indicator 14, but the thicker it is, the greater the difference between the baseline of the reflection spectrum and the reflectance in the selective reflection wavelength range will be, so it is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more.

[0032] There is no limitation on the means for observing the reflection spectrum corresponding to the temperature of the temperature measuring member and measuring the temperature, and it is possible to use visual comparison with a color sample, scanning with a spectrum analyzer, etc., and it is also possible to identify the temperature by separating and analyzing the color tone from the image. There is no particular limitation on the imaging device for acquiring the image, but a camera module combining an imaging element such as CMOS / CCD with a lens can be preferably used. In the module, it is preferable that the imaging element has a measurement sensitivity range that matches the color-producing wavelength of the member.

[0033] For the temperature measuring member defined in the present application, a method of observing the reflection spectrum corresponding to the temperature and measuring the temperature may be used in which the reflection spectrum corresponding to the temperature at a certain time is fixed at that time, and the reflection spectrum is measured according to the temperature change after that time. In this case, the measuring means does not need to be installed near the heating part, and the member of the present application may be taken out of the device and then measured in another place. As a method for fixing the reflection spectrum, the liquid crystal material can be polymerized and fixed. In a member using a liquid crystal material having an acryloyl group and containing a photoinitiator, the material can be fixed by irradiating light at a temperature timing to be measured, or in a member using a liquid crystal material having an acryloyl group and containing a thermal initiator, the material can be designed to generate radicals from the thermal initiator at a temperature timing to be measured and fixed. In order to generate radicals at a temperature timing to be measured, an acryloyl group that thermally decomposes in the same region can be used. Other reactions such as epoxy groups can be used for thermal polymerization, or a mechanism such as an acid generator can be used. As a means for initiating the reaction at the desired time for measurement, there are methods such as adding a polymerization inhibitor to prevent the reaction from occurring until a specified time has elapsed, or placing the initiator in a layer separate from the liquid crystal layer and diffusing it by heating so that the reaction does not begin until it reaches the liquid crystal layer.

[0034] As described above, when a method is used for observing a reflection spectrum corresponding to a temperature and measuring the temperature by fixing a reflection spectrum corresponding to a temperature at a certain time and measuring the reflection spectrum with temperature changes after that time, a layer that complements and reinforces the fixing mechanism may be provided. For example, in the case of a radical reaction, a layer that blocks a substance that inhibits the reaction (e.g., oxygen) may be provided on the opposite side (upper layer) of the temperature indicator to the substrate, or when inhibition from the lower layer is taken into consideration, the blocking layer may be provided on the substrate side.

[0035] The temperature indicator, temperature measuring member, and temperature measuring system of the present invention can be preferably used in a closed system or line system where it is difficult to handle wiring etc., when it is desired to measure a high-temperature heating part with high accuracy. For example, it can be preferably used for measuring the temperature distribution of a hot plate for semiconductor applications, or the temperature distribution on the surface of a heating roller in a film manufacturing process.

[0036] The temperature indicator and temperature measuring member of the present invention may be in the shape of a flat plate, or may have a curved surface or a three-dimensional structure in accordance with the configuration of the device and process.

[0037] The method for forming the temperature indicator of the present invention is not particularly limited, but it can be suitably formed by a spin coating method, a die coating method, a dip coating method, an inkjet method, etc. In each case, it can be preferably formed by dissolving in an appropriate solvent, forming a film, and then drying. EXAMPLES

[0038] The present invention will be described in further detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown below can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited to the following embodiments.

[0039] Example 1 A polyimide alignment film SE-130 (manufactured by Nissan Chemical Industries, Ltd.) was applied onto a cleaned glass substrate to form a coating film. The resulting coating film was baked and then subjected to a rubbing treatment to produce a substrate with an alignment film. Furthermore, composition 1 having the following composition was weighed and mixed. The mixture was mixed and stirred with a stirrer for about 1 hour while heating at 60° C., to prepare 2000 μL of composition solution 1. 100 μL of composition solution 1 was spin-coated on the rubbed surface of the alignment film at 500 rpm for 20 seconds to form a coating film, which was then dried at 130° C. for 1 minute to obtain a reflective film 1 with a thickness of about 3 μm.

[0040] (Composition 1) ---------------------------------------------------------------------------------- 0.3678 parts by weight of the following polymerizable liquid crystal compound L-1 0.0276 parts by mass of the following chiral agent K-1 0.0037 parts by weight of the following alignment agent T-1 ·MEK 0.800 parts by mass Cyclopentanone 0.800 parts by mass ----------------------------------------------------------------------------------

[0041] Polymerizable liquid crystal compound L-1

[0042] [ka]

[0043] Chiral agent K-1

[0044] [ka]

[0045] Orientation agent T-1

[0046] [ka]

[0047] (Examples 2 to 4, Comparative Example 1) Reflective films 2 to 4 of Examples 2 to 4 and comparative reflective film 1 of Comparative Example 1 were obtained in the same manner, except that compositions 2 to 4 and comparative composition 1 were used instead of composition 1 of Example 1. Each liquid crystal compound was synthesized by a synthesis method such as that described in Japanese Patent Application No. 2019-068662. The chiral agent was synthesized by a known synthesis method as described in Japanese Patent Application No. 2019-513701.

[0048] (Composition 2) ---------------------------------------------------------------------------------- 0.3721 parts by mass of the polymerizable liquid crystal compound L-1 0.0242 parts by mass of the chiral agent K-1 0.0037 parts by weight of the above alignment agent T-1 ·MEK 0.800 parts by mass Cyclopentanone 0.800 parts by mass ----------------------------------------------------------------------------------

[0049] (Composition 3) ---------------------------------------------------------------------------------- 0.3620 parts by weight of the following polymerizable liquid crystal compound L-2 0.0344 parts by mass of the chiral agent K-1 0.0036 parts by weight of the above alignment agent T-1 ·MEK 0.800 parts by mass Cyclopentanone 0.800 parts by mass ----------------------------------------------------------------------------------

[0050] Polymerizable liquid crystal compound L-2

[0051] [ka]

[0052] (Composition 4) ---------------------------------------------------------------------------------- 0.3620 parts by weight of the following polymerizable liquid crystal compound L-2 0.0344 parts by weight of the following chiral agent K-2 0.0036 parts by weight of the above alignment agent T-1 ·MEK 0.800 parts by mass Cyclopentanone 0.800 parts by mass ----------------------------------------------------------------------------------

[0053] Chiral agent K-2

[0054] [ka]

[0055] Comparative Example (Comparative Composition 1) ---------------------------------------------------------------------------------- 0.3774 parts by weight of the following polymerizable liquid crystal compound L-3 0.0189 parts by weight of the following chiral agent K-3 0.0038 parts by weight of the above alignment agent T-1 ·MEK 0.800 parts by mass Cyclopentanone 0.800 parts by mass ----------------------------------------------------------------------------------

[0056] Polymerizable liquid crystal compound L-3

[0057] [ka]

[0058] Chiral agent K-3

[0059] [ka]

[0060] (Reflection spectrum measurement) The reflectance spectrum was measured at each temperature using a spectrophotometer equipped with a temperature stage. The half-width and peak wavelength (wavelength exhibiting maximum reflectance) were determined from the waveform of the reflectance spectrum. From the temperature range in which the color tone changes, a temperature range in which the top peak of the spectrum changes in one direction (towards longer or shorter wavelengths) with increasing temperature was specified, and the absolute value of the ratio of the change in the corresponding top peak wavelength to the temperature difference between the lower limit temperature and the upper limit temperature was calculated as the temperature change rate.

[0061] (Evaluation of temperature measurement accuracy from color) For Examples 1 to 4 and Comparative Example 1, the samples were placed on a hot plate set to a temperature near the center of the color change temperature range, and the color was captured with a camera. The color data of the image captured this time was compared with the color data of the image captured in advance under the same imaging conditions, while the temperature of the sample was changed while being measured with a thermocouple, and the temperature of the central part was calculated. At that time, the temperature of the central part when the image was captured was measured separately with a thermocouple. The temperature measurement accuracy was evaluated according to the following criteria, based on a comparison of the measurement results with the thermocouple and the color data calculated from the image data. 6: Analysis of the image data gave temperature values ​​that matched very well with the thermocouple values. 5: Analysis of the image data gave temperature values ​​that matched well with the thermocouple values. 4: Analysis of the image data gave temperature values ​​that closely matched the thermocouple values. 3: Analysis of image data yielded values ​​close to the thermocouple values. 2: Analysis of image data yielded values ​​that were slightly different from the thermocouple values. 1: Analysis of image data yielded values ​​that differed from thermocouple values.

[0062] The evaluation results of Examples 1 to 4 and Comparative Example 1 are shown in Table 1. The peak wavelength and half-width changed in a unique direction with respect to the temperature change. From the results of Examples 1 to 4 and Comparative Example 1, it can be seen that the temperature can be quantified with high accuracy in the embodiment of the present invention. Furthermore, in this example, it was confirmed that the temperature difference between the center and the other parts of the sample can be detected as a difference in color, and it was confirmed that the surface temperature distribution can be detected with high accuracy by the present invention.

[0063] [Table 1] [Industrial Applicability]

[0064] This can be suitably used for measuring the surface temperature distribution of various heated locations, such as the surface temperature distribution of heated spots in semiconductor devices, the surface temperature distribution of heated rolls in film manufacturing, and the surface temperature distribution of cooking heating plates in food processing, as well as the surface temperature distribution of heated objects. [Explanation of symbols]

[0065] 10 Materials for temperature measurement 12 Base material 14 Temperature-indicating material

Claims

1. A member having a selective reflection wavelength range at 100°C or higher, wherein the peak wavelength of the reflection wavelength range changes by 1 nm / °C or more.

2. 10. The member of claim 1 comprising a liquid crystal material.

3. 3. The member according to claim 2, wherein the liquid crystal material has a phase transition temperature to an isotropic liquid of 200°C or higher.

4. 3. The member of claim 2, wherein the liquid crystal material has a polymerizable group.

5. 3. The member according to claim 2, wherein the liquid crystal material has cholesteric liquid crystal properties.

6. 6. The device of claim 5, further comprising one or more chiral agents.

7. 7. The member according to claim 6, wherein the rate of change of the helical twisting power (HTP) of the chiral agent with temperature is 0.15% / °C or more.

8. The member according to claim 1 , wherein the peak wavelength of the selective reflection wavelength is in the range of 200 nm to 1500 nm.

9. The member according to claim 1 , wherein the half-width of the reflection spectrum at the selective reflection wavelength is 100 nm or less.

10. 3. The member according to claim 2, wherein the liquid crystal material has a temperature range in which it exhibits a smectic A phase.

11. The component of claim 10 further comprising a chiral agent.

12. 10. The component of claim 1, wherein the component is heat polymerizable.

13. A temperature measuring material comprising the member according to any one of claims 1 to 12 and a substrate.

14. A temperature sensor comprising the member according to any one of claims 1 to 12, for identifying a temperature by measuring a reflection spectrum.

15. The member according to any one of claims 1 to 12, wherein the reflection spectrum changes in response to the temperature at a predetermined time, and the reflection spectrum does not change with temperature changes after the predetermined time.

16. 13. A temperature sensor comprising the member according to claim 1, wherein the reflection spectrum changes in response to the temperature at a predetermined time, and the reflection spectrum does not change with temperature changes after the predetermined time, and wherein the temperature sensor measures the reflection spectrum corresponding to the temperature at the predetermined time at a time after the predetermined time, and identifies the temperature at the predetermined time.

17. A sensing system for identifying a surface temperature by measuring the reflection spectrum of the temperature sensor of claims 14 and 16 as an image.

Images