JP2012088210A - Indicator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an indicator having both a function to check if a predetermined temperature and time are applied to an object by a visual check for discoloration and a function of a temperature sensor.SOLUTION: An indicator 10, which is a time-temperature integrating indicator (TTI), comprises: a base material 11; a first conductive film 21 and a second conductive film 22 formed on the base material 11; and a mixture 13 of a pigment and a conductive polymer. The mixture 13 of the pigment and the conductive polymer is in contact with the first conductive film 21 and the second conductive film 22 so as to connect the films. The pigment in the mixture 13 is composed of a material in which a double bond is broken at a decomposition temperature to be discolored. The conductive polymer in the mixture 13 has a decomposition temperature that is higher than that of the pigment. In the indicator 10, an electric resistance between the first conductive film 21 and the second conductive film 22 varies at a decomposition temperature of a material of the pigment.

Description

  The present invention relates to an indicator, and more particularly to a thermal time integration type indicator designed to change color at a predetermined temperature and time.

  Foods have expiry dates, but these must be based on the expected storage conditions (temperature, humidity, sunlight, etc.) of a particular product. Therefore, the recommended storage state is also specified. However, since the actual storage state cannot be predicted and controlled, a time-temperature integration type indicator is required. In medical sterilization, a chemical indicator (CI) is used for visually confirming whether the temperature and time required for sterilization have been applied to the object to be sterilized. CI is generally formed by applying a pigment designed to change color at a sterilizable temperature and time (for example, when 121 ° C. is added for 20 minutes). So-called thermolabels that change color at a certain temperature cannot add such time.

  In a broad sense, an indicator is a display, indicator, indicator, indicator, indicator, indicator, indicator, and a wide range of objects to be measured. The type of time indicator that can be confirmed by discoloration or the like whether or not the necessary conditions are satisfied will be described.

  There are two types of time indicators. One considers not only time but also cumulative heat exposure applied to the object. This is accomplished by increasing the rate of change of the indicator with temperature as a function. Some of these indicators respond continuously to changes in temperature and others need to reach a threshold temperature so that they do not change color below a certain temperature. For example, in the case of an indicator used for sterilization work, it is necessary to take into account the accumulated time above the sterilizable temperature. These are generally called a “time-temperature indicator” or a “time-temperature indicator (TTI)”. The other is non-heat sensitive and provides a visual indication of elapsed time, commonly referred to as a “timer”.

  TTI indicates that a certain temperature or more has been applied for a certain period of time, such as deadline monitoring of items that are subject to corruption, such as food, food additives, biological materials, drugs, and cosmetics, and sterilization and sterilization in food and medical settings. This is very useful when an operator visually confirms. On the other hand, timers are useful for items that do not rot, such as alerts that need to be replaced, completed or updated. However, the above are application examples and are not limited thereto.

  The TTI and the timer are realized using a chemical reaction mechanism, a diffusion mechanism, and a capillary phenomenon mechanism. Since the time indicator can be visually confirmed by discoloration or the like, it can be evaluated that the user can judge a defect at a glance. However, when the evaluation is performed based on the degree of discoloration, there is a possibility of individual differences in the determination result because it is not a quantitative evaluation. Therefore, although quantification may be performed with a chromaticity meter, the chromaticity meter is expensive, and a large amount of objects is a heavy burden on the operator. Therefore, there is an indicator that accepts when a certain area is reached (Sumitomo 3M Co., Ltd.) based on the length of the area where the liquid is gradually infiltrated into the slender paper, for example, by utilizing capillary action instead of discoloration. With this method, quantitative evaluation is possible.

  In recent years, in order to ensure food and medical safety, traceability indicating that the distribution channel of goods can be traced from the production stage to the final consumption stage or the disposal stage has been regarded as important. There is an increasing need to capture information into a personal computer (hereinafter referred to as a PC). In such a case, it is the present situation that the operator often inputs the evaluation result of the indicator into the PC, and a radio frequency identification (RFID) is used for labor saving and unmanned work. I'm starting.

  RFID is a kind of automatic recognition / data carrier similar to a bar code or the like. In a barcode, a two-dimensional code optically reads, whereas an RFID uses radio waves. Compared with barcodes, RFID can be read without contact even with a shield such as a cardboard box, and can read multiple RFIDs at the same time. In general, it can write and read hundreds of bits of data. . In addition, RFID performs object recognition, personal authentication, etc. by attaching IC chips with antennas processed into tags and labels to people and objects, and reading information stored there with a device called a reader / writer Is. One advantage of using RFID is that contactless authentication can be performed without touching a recognition object, and the other is that such contactless authentication can be performed simultaneously on multiple objects. This is a point of multiple simultaneous authentication. With these features, many business operations currently being performed by humans can be automated or simplified, enabling enormous cost savings, and preventing human error and systems. By improving the real-time nature of information, the quality of information is improved, and it is also expected to support accurate understanding of corporate resources and prompt decision making.

  By the way, there is a device called “Temperature Logger” as a device that records the temperature history of food, etc., and it has been used by food manufacturers for temperature management in the manufacturing process and distribution stage, but it is connected to a PC with a cable. If you don't, you won't be able to download data. In addition, the main body is large, which is an obstacle to collecting data frequently on a daily basis.

  On the other hand, RFID with a temperature sensor has the great convenience of being able to start / stop temperature collection / sucking data without contact, and it is downsized by using one chip (equipped with an RFID circuit / temperature sensor on one silicon chip). At the same time, there are expectations for cost reduction due to the reduction in the number of parts. In addition, the indicator by the combination of a temperature sensor and RFID is disclosed by patent document 1.

  FIG. 6 is a cross-sectional view of each example of the indicator described in Patent Document 1. The indicator shown in FIG. 6A includes a base material 1 having a microstructure surface that defines a plurality of channels 4, a conductive layer 2 disposed close to the microstructure surface of the base material 1, and an insulator layer 3. It consists of Channel 4 is designed so that the fluid travels at the desired constant speed. The conductive layer 2 is disposed in close proximity to the microstructure surface of the substrate 1, and comes into contact with the conductive or dielectric fluid moving through the channel 4 of the substrate 1, thereby causing resistance, current, It can be read as a change in voltage. The conductive layer 2 preferably has the patterning shown in FIG. When a dielectric fluid is used, an insulating layer 5 is provided as shown in FIG. 6B, and an electrode is formed on a part of the channel 4 so that it can be read as a capacitance change.

Special table 2008-516208 gazette

  However, the conventional indicator shown in the sectional view of FIG. 6A has a complicated structure, and the other conventional indicator shown in the sectional view of FIG. 6B has a more complicated structure.

  In addition, RFID with temperature sensor cannot be confirmed by visual inspection of the tag itself, and cannot be confirmed directly by an operator who does not have a reader. Therefore, rapid processing cannot be performed, and mistakes and misrecognition are possible. There is also sex. Desirably, the barometer for discoloration or the like is an RFID that can be confirmed by an operator's visual observation and can be taken out as an electrical signal.

  Here, the combination of TTI for visual observation and RFID with temperature sensor for electric signal extraction is also conceivable. However, the double cost is required, and if the correspondence between the two is not taken, the judgment standard becomes difficult and erroneous judgment is made. This is not preferable.

  The present invention has been made in view of the above points, and an object thereof is to provide an indicator having a function of visually confirming whether a predetermined temperature and time have been applied to an object and a function of a temperature sensor. To do.

  Another object of the present invention is to provide an indicator having a simple configuration at low cost.

  In order to achieve the above object, an indicator of the present invention includes a base material, a first conductive film and a second conductive film formed on the base material, a first conductive film, and the second conductive film. A mixture of a dye made of a material that discolors due to the breakage of a double bond at a decomposition temperature, and a conductive polymer having a decomposition temperature higher than the decomposition temperature of the dye. The resistance value between the first and second conductive films varies depending on the decomposition temperature of the dye.

  According to the present invention, an indicator having a function of visually confirming whether a predetermined temperature and time have been applied to an object and a function of a temperature sensor can be realized with a simple configuration.

It is sectional drawing of one Embodiment of the indicator of this invention, the top view before a heating, and the top view after a heating. It is a figure explaining the mode of experiment of Example 1 of the indicator of this invention. It is a graph which shows the temperature change and resistance value change with respect to time of the prototype of Example 1 of the indicator of the present invention. It is a figure explaining the ITO electrode pattern used for Example 1. FIG. It is the external view which combined the indicator and RFID of this invention, and the block diagram of an example of an RFID chip. It is sectional drawing of an example of the indicator of patent document 1. FIG. It is a figure which shows the electrode part of the indicator of patent document 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1A, 1B, and 1C are a cross-sectional view of an embodiment of an indicator according to the present invention, a top view before heating, and a top view after heating. As shown in FIGS. 3A to 3C, the indicator 10 of the present embodiment includes a base material 11, a first conductive film 21 and a second conductive film provided on the base material 11. 22 is a thermal time integrating indicator (TTI) composed of a mixture 13 of a dye and a conductive polymer. The mixture 13 of the dye and the conductive polymer is provided so as to connect the first conductive film 21 and the second conductive film 22. In addition, the substrate 11, the conductive films 21 and 22, and the mixture 13 of the dye and the conductive polymer are covered with a cover 14.

  As the base material 11, the decomposition temperature of most dyes generally exceeds 150 ° C., so that it can withstand the use temperature and is insulative and does not absorb and penetrate the mixture of the dye and the conductive polymer Any glass substrate may be used as long as it has sufficient strength to support the article, but from the viewpoint of productivity and cost, polyphenylene sulfide (PPS), polyarylate (PAR), polysulfone (PSF), High heat-resistant plastics such as polyethersulfone (PES), polyetherimide (PEI), polyamideimide (PAI), polyetheretherketone (PEEK), and liquid crystal polyester (LCP) are preferred.

  The first conductive film 21 and the second conductive film 22 on the substrate 11 may be a metal thin film, ITO (Indium Tin Oxide), or the like. However, since a vacuum process is required, considering the productivity, the aluminum foil It is desirable that the sheet is a conductive sheet such as a metal foil such as a resin, paper or the like laminated with a metal foil. It is necessary to select a material that can withstand the operating temperature as a material used for bonding the base material 11, the first conductive film 21, and the second conductive film 22.

  The dye used in the mixture 13 may be any material that can break the double bond at the decomposition temperature. For example, a cyanine dye, an azo dye, or a phthalocyanine dye may be used alone or in appropriate combination of two or more. be able to. These decomposition temperatures are usually about 150 ° C to about 250 ° C. Cyanine dyes and the like have many double bonds and are rich in π electrons, but they do not exhibit conductivity when used alone.

  Moreover, it is necessary to select the conductive polymer material used for the mixture 13 that has a decomposition temperature higher than the decomposition temperature of the pigment used in combination. For example, polypyrrole (decomposition temperature 300 ° C.) and polyethylene dioxythiophene (decomposition temperature 350 ° C.) are suitable.

  The cover 14 covers part or all of the base material 11, the conductive films 21 and 22, and the mixture 13 of the dye and the conductive polymer. The cover 14 may be flexible, semi-rigid or rigid and is preferably selected such that it does not interfere with the operation of the indicator. Further, the cover 14 is insulating and can be made of various materials such as high heat-resistant resin and paper, and may be a single structure or a structure formed by joining several pieces. Moreover, you may produce with the opaque material provided with the transparent window which can see the discoloration degree of a pigment | dye. The cover 14 is joined in various ways including, for example, lamination of the pressure sensitive adhesive tape to the substrate 11 such that the tape backing is the cover.

  According to the indicator 10 of the present embodiment, the mixture 13 of the dye and the conductive polymer connecting the first conductive film 21 and the second conductive film 22 is the dye constituting the mixture. Since the dye material discolors because the double bond is broken at the decomposition temperature, for example, it can be used as a heat time integration type indicator that can visually confirm whether or not a sterilizable temperature and time have been applied to an object to be sterilized by discoloration.

  Further, according to the indicator 10 of the present embodiment, as described later, the phenomenon that the double bond is broken and the resistance value rises when the decomposition temperature of the dye is reached can also be used as a temperature sensor.

  Next, Example 1 of the present invention will be described. Details of the configuration of Example 1 of the indicator of the present invention that was experimentally manufactured for confirming the operating principle of the indicator of the present invention and the experimental results are shown below.

  Cyanine dye (decomposition temperature 170 ° C) powder and PEDOT / PSS (poly (2,3-dihydrothieno-1,4-dioxin) -poly (styrenesulfonate)) (hereinafter PEDOT / PSS) are difficult to mix directly. As shown in FIG. 2A, first, 0.03 g of a cyanine dye was dispersed in 2 ml of DMF (N, N-dimethylformamide) (cyanine + DMF) and mixed 1: 1 with PEDOT / PSS to obtain a mixed solution 18 It was created.

  Next, a glass substrate 15 on which an ITO film having a thickness of 50 μm as shown in FIG. 2C is patterned at a pitch of 100 μm is heated to about 140 ° C. on a hot plate, and the pattern shown in FIG. Then, 0.1 ml of the mixed liquid 18 was dropped, and after rotating for 10 seconds at 500 rpm with a spin coater, the mixed film 181 was formed by rotating for 30 seconds at 2000 rpm. Thereafter, it was heated and dried on a hot plate for about 5 minutes. As shown in FIG. 2B, the ITO electrode 16 is connected to a tester 17 (for example, a digital high tester 3801-50 manufactured by Hioki Electric Co., Ltd.) so that the resistance can be observed. The resistance value of this sample at room temperature was 97.1 [kΩ].

  In the oven, it was difficult to observe the entire operation of the prototype of this indicator, so an experiment was conducted using a hot plate capable of controlling the PID temperature. FIG. 3 shows the resistance measurement results when the substrate 15 is placed on a hot plate and the temperature is gradually increased from 140 ° C. to 200 ° C. in 5 minutes.

  As shown in FIG. 3, the substrate temperature reached 170 ° C. after about 2 minutes, and the resistance value that had decreased with the temperature rise until then began to increase rapidly from that moment. When a similar experiment was conducted with a cyanine dye having a decomposition temperature of 210 ° C., the same tendency was observed, and it was confirmed that the temperature at which the resistance began to rise was equal to the decomposition temperature of the dye. In addition, it can be seen that the mixed film 181 colored in a dark blue color is almost black after pyrolysis, and the dye is faded and only the PEDOT / PSS color remains. The resistance value when the substrate 15 was cooled to room temperature was about 200 [kΩ].

  Similarly, the temperature control was increased from 140 ° C. to 170 ° C. over 5 minutes, and then kept constant at 170 ° C. for 5 minutes. Although the resistance value at room temperature before heating was 84.6 [kΩ], it became 108 [kΩ] after heating, and the color of the mixed film 181 remained slightly bluish. When the temperature was constant at 170 ° C. for 10 minutes, the resistance value was 80.6 [kΩ] before heating and 144 [kΩ] after heating. At this time, the color of the mixed film 181 was slightly black as compared with a case where the color was constant at 170 ° C. for 5 minutes.

  Furthermore, when the temperature is kept constant at 170 ° C. for 3 minutes and then once changed to 150 ° C. and again kept constant at 170 ° C. for 5 minutes, the resistance value is 86.8 [kΩ] before heating, but the resistance is 120 [ kΩ], and the color of the mixed film 181 was an intermediate color when the temperature was constant at 170 ° C. for 5 minutes and when it was constant at 170 ° C. for 10 minutes.

  Therefore, by measuring the final resistance value at room temperature, it is possible to know how long a constant temperature equal to the decomposition temperature has been applied, and it can also be determined from discoloration by visual observation.

  In addition, even when a DMF solvent pigment is dropped on the ITO electrode 16, there is no electrical conductivity. When the same experiment is performed using only PEDOT / PSS, the resistance value decreases with increasing temperature, but does not increase. It was confirmed in advance that the amount of change in the resistance value at the time was at most + (full-width) 5 [kΩ], which was clearly smaller than when the mixed solution was used. Therefore, using this phenomenon, it became clear that it functions as a temperature sensor by reading the increase / decrease in resistance between the two ITO electrodes 16. Further, when the ITO electrode 16 is patterned on the substrate 15 as shown in FIG. 4B, the lateral resistance is lower than when the interval in FIG. There is.

  In Example 1, the DMF solvent dye and PEDOT / PSS were mixed at a ratio of 1: 1. However, increasing the ratio of the dye increases the amount of change in resistance at the decomposition temperature. However, since the resistance of the mixed liquid itself increases, it needs to be adjusted appropriately.

  According to the first embodiment, complicated electrode patterning is not necessary, and the structure is simple and can be manufactured at a very low cost.

  Thus, in the indicator of Example 1, the resistance gradually decreases as the mixture 13 of the dye and the conductive polymer is heated, and the double bond is broken at the decomposition temperature of the dye material. It can be used as a temperature sensor by utilizing the phenomenon that the resistance value increases.

  The change in the resistance value of the indicator of the present invention can be taken out as an electric signal indicating whether or not the conductive film is conductive. Therefore, it can be managed smoothly by combining with the RFID. The RFID combined with the indicator of the present invention is preferably a passive tag that can be realized at low cost. A passive tag does not have a power source on the tag side, and uses a radio wave emitted from a reader / writer as power.

  The indicator of Example 2 has a configuration in which the thermal time integration type indicator (TTI) 10 of the present embodiment shown in FIG. 1 and an RFID tag are combined, and FIG. b) shows a block diagram of an example RFID tag. The configuration of this RFID tag refers to “a shelf label system with a temperature management function using a battery-less RFID tag” described in Japanese Patent Application Laid-Open No. 2007-111137.

  In FIG. 5A, the TTI 10 of this embodiment is connected to the RFID chip 31. The RFDI chip 31 includes an RFID tag 33 including an antenna 32 for communication with a reader / writer. Here, the RFID chip 31 is shown in the block diagram of FIG.

  In FIG. 5B, an antenna 32 is connected to a tuning circuit 34 to perform radio communication with a reader / writer using electromagnetic waves, and is tuned to a carrier frequency to constitute a resonance circuit. At the subsequent stage of the tuning circuit 34, the voltage waveform of the induced electromotive force generated when the electromagnetic wave transmitted from the reader / writer antenna passes through the antenna 32 of the RFID tag is detected, and the induced electromotive force is detected as a half wave or a full wave. It is connected to a rectifier circuit 35 for rectifying and extracting a DC voltage.

  Next, after the rectifier circuit 35, a clock generation circuit 36 for generating a system clock by dividing the detected carrier, a demodulation operation for extracting a signal from the carrier at the time of signal reception, and a signal transmission time A modulation / demodulation circuit 37 for modulation operation is connected by a switching element (not shown). Further, following the modulation / demodulation circuit 37, the control of the modulation / demodulation circuit 37, the unique ID information of the RFID chip 31 for the FRAM (Ferroelectric RAM: registered trademark of Ramtron, USA) 39, and the TTI 10 of the present embodiment A logic circuit 38 is connected to perform data writing or reading control of any one of the capacitance, resistance, voltage, and current signals detected in (1). In addition, an A / D converter that converts any one of the capacitance, resistance, voltage, and current signals output from the TTI 10 of the present embodiment into an appropriate digital value, and the TTI 10 are connected. An interface circuit 40 is connected to the logic circuit 38 and the FRAM 39. The FRAM 39 is a ferroelectric nonvolatile memory, and data such as the unique ID information of the RFID chip 31 is not lost even when the circuit power is turned off. The frequency to be used varies depending on the communication distance and application, and a frequency band corresponding to the communication distance may be used.

  Conventional TTI is a visual chemical indicator, and the indicator due to discoloration has low accuracy. The alternative is an electronic device that requires an electronic display for display, is expensive, large and requires a power source.

  On the other hand, the TTI 10 of this embodiment can be manufactured at an extremely low cost as compared with an electronic device. Furthermore, by combining the TTI of the present embodiment with an RFID tag, it is possible not only to visually confirm whether a predetermined temperature has been applied to a target object for a predetermined time by color change, but the information on the color change is directly output from the RFID tag. Therefore, the temperature history can be read by recording the resistance change of the TTI of the present embodiment in the memory.

  The indicator of the present invention is designed to change color at the sterilizable temperature and time in order to visually check whether the sterilizable temperature and time have been applied to the object to be sterilized in the high pressure steam sterilization of the medical device. It can be used as a heat time integration type indicator and can be used not only for visual confirmation but also as a temperature sensor that outputs a detection signal when a predetermined temperature is applied for a certain period of time.

10 Thermal time integration type indicator (TTI)
DESCRIPTION OF SYMBOLS 11 Base material 13 Mixture of pigment | dye and conductive polymer 15 Glass substrate 16 ITO electrode 17 Tester 21 First conductive film 22 Second conductive film 31 RFID chip 32 RFID tag 34 Tuning circuit 35 Rectifier circuit 36 Clock generation circuit 37 Modulation / demodulation circuit 38 Logic circuit 39 FRAM (Ferroelectric RAM)
40 Interface circuit

Claims (1)

A substrate;
A first conductive film and a second conductive film formed on the substrate;
The first conductive film and the second conductive film are connected to each other, and have a dye that is discolored due to a double bond being broken at the decomposition temperature, and a decomposition temperature that is higher than the decomposition temperature of the dye. A mixture with a conductive polymer;
The resistance value between the first and second conductive films changes at the decomposition temperature of the dye.