Calorimetric label as well as preparation method and use method thereof

Abstract

The invention provides a calorimetric label as well as a preparation method and a use method thereof. The calorimetric label comprises two laminated parts of a thermosensitive functional layer and an adsorption indicating layer which are physically independent from each other before use, and the two laminated layers are respectively produced, stored and transported and are combined together during use. The accumulated heating capacity range measured and monitored by the calorimetric label is the accumulated heating capacity within 7-45 days at the temperature of 6 DEG C, the Q25 DEG C / 6 DEG C value reflecting the temperature effect of the calorimetric label is 7.5 + / -1.0, and the calorimetric label can be used for monitoring the cold-chain logistics process within the corresponding accumulated heating capacity range and can also be used for monitoring the whole life cycle of heat-sensitive articles with the shelf life of 7-45 days at the temperature of 6 DEG C, and the application prospect is wide. And the cost is low, and the storage and transportation conditions are friendly.

Description

Technical Field

[0001] This application relates to the field of cold chain logistics process monitoring technology, and in particular to a calorimetric label and its preparation and usage methods. Background Technology

[0002] Some temperature-sensitive items or products require cold chain storage or transportation, such as most vaccines, biological products, bioactive samples, and some pharmaceuticals, as well as fresh foods such as fresh milk, dairy products, fresh meat, and fresh fish. To ensure the quality and effectiveness of these heat-sensitive items, continuous monitoring and management of all aspects of the cold chain storage and transportation process are necessary.

[0003] The currently prevalent management model is based on temperature monitoring, which involves continuously recording and controlling the temperature of different links in the cold chain, such as cold storage facilities, transport vehicles, and refrigeration and freezing equipment. As a process management model, temperature monitoring and recording at each node of the cold chain is an effective and irreplaceable approach for maintaining and managing the cold chain. In particular, the widespread adoption of digital temperature monitoring networks has greatly improved the quality and effectiveness of cold chain logistics management. At the same time, the industry has also developed supplementary temperature monitoring tools to meet diverse user needs, such as Timestrip's over-temperature indicator tags and Temptime's freezing indicators and over-temperature indicator tags.

[0004] Another management model is based on heat monitoring. A representative example is Temptime's VVM (Vaccine Vial Monitor) technology, adopted by the World Health Organization (WHO). This technology uses a solid-phase polymerization chemical reaction process accompanied by color changes to measure the cumulative heat absorbed by the vaccine throughout its lifespan, alerting users to excessively heated vaccines to ensure the effectiveness and safety of vaccination. Recently, patents CN 201210567490.4 and CN 201710222789.9 also disclosed a heat monitoring technology that uses a dye sublimation-diffusion-adsorption process to measure the cumulative heat absorbed by vaccines or other heat-sensitive items throughout their lifespan.

[0005] The characteristic of heat monitoring-based management models is that they simultaneously incorporate both time and temperature factors into the monitoring process, and possess better metrological capabilities, enabling more accurate reflection of the heating history of heat-sensitive items and judgment of consequences. However, the aforementioned widely adopted or publicly available heat monitoring technologies can only be used for monitoring the entire lifecycle of heat-sensitive items with long shelf lives, such as vaccines and pharmaceuticals. The cold chain logistics industry has been eagerly awaiting a heat monitoring technology with a shorter response time that can be used for monitoring the entire cold chain logistics process. While Timestrip's over-temperature indicator label also incorporates both temperature and time factors and has been applied in cold chain logistics process monitoring, its response process only occurs above a set temperature threshold. Therefore, it does not account for the heat absorbed by heat-sensitive items during storage and transportation below the set temperature threshold, and thus it is not a heat monitoring technology in the strict sense. Moreover, the product cost of this technology is relatively high.

[0006] Therefore, the cold chain logistics industry urgently needs a low-cost heat monitoring technology and product that can be used for monitoring the cold chain logistics process. Summary of the Invention

[0007] The purpose of this application is to provide a calorimetric label and its preparation and application methods for monitoring the cumulative heat received during cold chain logistics processes within a range of 7-45 days at 6°C. It can also be used for full life-cycle monitoring of heat-sensitive items with a shelf life of 7-45 days at 6°C, and is cost-effective and suitable for storage and transportation. The specific technical solution is as follows:

[0008] The first aspect of this application provides a calorimetric label for monitoring cold chain logistics processes, comprising two stacked parts that are physically independent before use: a thermosensitive functional layer and an adsorption indicator layer. The thermosensitive functional layer includes: a first sealing film layer; a dye substrate layer formed on the first sealing film layer; and a sublimable dye layer formed on the dye substrate layer, the sublimable dye layer containing a sublimable dye, wherein the sublimable dye is an acetyl-substituted azulene derivative as shown in Formula 1. Formula 1, wherein R is hydrogen or methyl; a first release film layer located below a first sealing film layer, the dimensions of the first release film layer and the first sealing film layer being larger than the dimensions of the sublimable dye layer; and an adsorption indicator layer comprising: a second sealing film layer made of a transparent material; an indicator layer located above the second sealing film layer and having an observation window with a reference color surrounding the observation window; an adsorption layer located below the second sealing film layer, the adsorption layer overlapping or overlapping the observation window in the vertical direction; an isolation layer located below the adsorption layer and made of an opaque material, the size of the isolation layer being larger than the size of the observation window and smaller than the size of the adsorption layer; and a second release film layer located below the isolation layer and covering the isolation layer.

[0009] In some embodiments of this application, the cumulative heat received by the calorimetric tag is measured within the range of 7-45 days at 6°C, reflecting the temperature effect of the calorimetric tag's thermal response. 25℃ / 6℃ The value is 7.5 ± 1.0, where Q 25℃ / 6℃ =t 6℃ / t 25℃ , t 6℃ t is the time required for the calorimeter label to reach the optical density (OD) value of the set endpoint color at 6℃. 25℃ The time required for the calorimeter label to reach the optical density (OD) value of the set endpoint color at 25℃, OD = log0 10 (I 入 / I 反 ), I 入 I represents the incident light intensity of the calorimeter tag. 反 This represents the intensity of the reflected light from the calorimeter label.

[0010] In some embodiments of this application, the upper surface of the first sealing film layer contains positioning information of the dye substrate layer.

[0011] In some embodiments of this application, the dye substrate layer includes coated paper, and the coated surface of the coated paper is bonded to the first sealing film layer by an adhesive, which includes water-based adhesive or solvent-based adhesive.

[0012] In some embodiments of this application, the first release film layer and the first sealing film layer are bonded together by an adhesive, which includes water-based adhesive or solvent-based adhesive.

[0013] In some embodiments of this application, an indicator layer is formed on the second sealing film layer and located on the upper surface of the second sealing film layer.

[0014] In some embodiments of this application, the indicator layer is a separate reference layer made of a white polymer film. The material of the indicator layer includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid, or nylon. The indicator layer is bonded to the second sealing film layer by an adhesive.

[0015] In some embodiments of this application, the depth of the reference color of the indicator layer around the observation window is the same as the depth of the color presented in the observation window by the adsorption layer due to the adsorption of sublimated dye from the sublimated dye layer after the sublimated dye layer has undergone a set heat exposure process.

[0016] In some embodiments of this application, the adsorption layer itself is formed of transparent self-adhesive, including water-based self-adhesive or solvent-based self-adhesive.

[0017] In some embodiments of this application, the isolation layer is made of an opaque porous material, including at least one of offset paper or coated paper.

[0018] In some embodiments of this application, the materials of the first sealing film layer and the second sealing film layer each independently include at least one of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid, or nylon.

[0019] In some embodiments of this application, the materials of the first release film layer and the second release film layer each independently include at least one of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid, or nylon.

[0020] In some embodiments of this application, the size of the isolation layer is greater than or equal to the size of the sublimation dye layer.

[0021] The second aspect of this application provides a method for preparing the calorimetric label provided in the first aspect of this application, comprising the following steps: providing a first sealing film layer; forming a dye substrate layer on the first sealing film layer; forming a sublimable dye layer on the dye substrate layer, the sublimable dye layer containing a sublimable dye, the sublimable dye being an acetyl-substituted azurite derivative as shown in Formula 1: Formula 1, wherein R is hydrogen or methyl; a first release film layer is provided under the first sealing film layer, the dimensions of the first release film layer and the first sealing film layer being larger than the dimensions of the sublimable dye layer, forming a thermosensitive functional layer; and a second sealing film layer formed of a transparent material is provided; an indicator layer is formed on the second sealing film layer, the indicator layer having an observation window and a reference color around the observation window; an adsorption layer is formed under the second sealing film layer, the adsorption layer overlapping or overlapping the observation window in the vertical direction; an isolation layer is formed under the adsorption layer by an opaque material, the size of the isolation layer being larger than the size of the observation window and smaller than the size of the adsorption layer; and a second release film layer is covered under the isolation layer to form an adsorption indicator layer.

[0022] In some embodiments of this application, the sublimable dye is formed by coating or impregnating the upper surface of the dye substrate layer to form a sublimable dye layer.

[0023] In some embodiments of this application, a color masking layer is first printed with white ink on the upper surface of the second sealing film layer, and then a reference color is printed on the color masking layer, with an observation window reserved in the middle area of ​​the reference color to form an indicator layer.

[0024] In some embodiments of this application, a separate reference layer formed of a white polymer film is provided, a reference color is printed on the upper surface of the separate reference layer, and an observation window is formed by die-cutting in the middle area of ​​the reference color. An adhesive is coated on the lower surface of the separate reference layer and bonded to a second sealing film layer to form an indicator layer.

[0025] The third aspect of this application provides a method for using the calorimetric label provided in the first aspect of this application, comprising the following steps: providing a thermally sensitive functional layer and an adsorption indicator layer of the calorimetric label; removing the second release film layer from the adsorption indicator layer; aligning the isolation layer of the adsorption indicator layer (with the second release film layer removed) with the sublimation dye layer of the thermally sensitive functional layer, and attaching it to the thermally sensitive functional layer to complete the assembly of the calorimetric label; removing the first release film layer of the thermally sensitive functional layer, attaching the assembled calorimetric label to the object to be monitored, and activating the monitoring function of the calorimetric label.

[0026] In some embodiments of this application, the cumulative heat exposure status of the monitored object is determined by observing the color change of the adsorption layer through the observation window of the calorimetric label and comparing it with a reference color. Any of the following three situations will occur: if the color observed through the observation window is lighter than the reference color, it indicates that the cumulative heat exposure of the monitored object is still within the limit set by the calorimetric label; if the color observed through the observation window is the same as the reference color, it indicates that the cumulative heat exposure of the monitored object has reached the limit set by the calorimetric label; if the color observed through the observation window is darker than the reference color, it indicates that the cumulative heat exposure of the monitored object has exceeded the limit set by the calorimetric label.

[0027] The fourth aspect of this application provides a heat-sensitive article using the calorimetric label provided in the first aspect of this application.

[0028] In some embodiments of this application, heat-sensitive items include cooked food, beverages, fruits, dairy products, fresh meat products, aquatic products, and plasma or blood products for clinical transfusion that require low-temperature storage and transportation.

[0029] The production cost of the calorimetric labels provided in this application is much lower than that of similar products used in related fields on the market, and the storage and transportation conditions are more favorable, which is conducive to their promotion and application in related application fields, so that more industries or individuals can benefit from the products provided in this application.

[0030] This application provides a calorimetric label, its preparation method, and its usage method. The calorimetric label comprises two physically independent layers before use: a heat-sensitive functional layer and an adsorption indicator layer. These two layers are manufactured, stored, and transported separately, and are combined together during use. The calorimetric label of this application measures the cumulative heat received over a range of 7-45 days at 6°C, reflecting the temperature effect of the calorimetric label's thermal response.25℃ / 6℃ With a value of 7.5±1.0, it can be used for monitoring the cold chain logistics process within the corresponding cumulative heat range, as well as for monitoring the entire life cycle of heat-sensitive items with a shelf life of 7-45 days at 6℃. It is also low in cost and friendly to storage and transportation conditions.

[0031] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0033] Figure 1 This is a schematic diagram of the structure of a calorimetric label along its own thickness direction according to one embodiment of this application;

[0034] Figure 2 The sublimable dye 1-acetylazine used in one embodiment of this application 1 H NMR spectrum;

[0035] Figure 3 The sublimable dye 3-methyl-1-acetylazine used in another embodiment of this application 1 H NMR spectrum;

[0036] Figure 4 This is a graph showing the change of OD value of the observation window of the calorimetric label of Embodiment 1 of this application during incubation at 6°C as a function of incubation time;

[0037] Figure 5 This is a graph showing the change of OD value of the observation window of the calorimetric label of Embodiment 1 of this application with incubation time at 25°C.

[0038] Figure 6 This is a graph showing the change of OD value of the observation window of the calorimetric label of Embodiment 2 of this application during incubation at 6°C as a function of incubation time;

[0039] Figure 7 This is a graph showing the change of OD value of the observation window of the calorimetric label of Embodiment 2 of this application during incubation at 25°C as a function of incubation time;

[0040] Figure 8 This is a graph showing the change of OD value of the observation window of the calorimetric label of Comparative Example 1 of this application with incubation time at 25°C.

[0041] Figure 9This is a graph showing the change of OD value of the observation window of the calorimetric label of Comparative Example 2 of this application with incubation time at 25°C.

[0042] Figure 10 This is a diagram showing the color change effect of the calorimeter label in the usage process of Embodiment 1 of this application.

[0043] Reference numerals: 1. Thermosensitive functional layer; 10. Dye substrate layer; 11. Sublimable dye layer; 12. Adhesive; 13. First sealing film layer; 14. First release film layer.

[0044] Adsorption indicator layer 2, second sealing film layer 20, adsorption layer 21, adsorption indicator area 22, isolation layer 23, indicator layer 24, reference color 25, observation window 26. Detailed Implementation

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0046] The first aspect of this application provides a calorimetric label for monitoring cold chain logistics processes, comprising two stacked parts that are physically independent before use: a thermosensitive functional layer and an adsorption indicator layer. The thermosensitive functional layer includes: a first sealing film layer; a dye substrate layer formed on the first sealing film layer; and a sublimable dye layer formed on the dye substrate layer, the sublimable dye layer containing a sublimable dye, wherein the sublimable dye is an acetyl-substituted azulene derivative as shown in Formula 1. Formula 1, wherein R is hydrogen or methyl; a first release film layer located below a first sealing film layer, the dimensions of the first release film layer and the first sealing film layer being larger than the dimensions of the sublimable dye layer; and an adsorption indicator layer comprising: a second sealing film layer made of a transparent material; an indicator layer located above the second sealing film layer and having an observation window with a reference color surrounding the observation window; an adsorption layer located below the second sealing film layer, the adsorption layer overlapping or overlapping the observation window in the vertical direction; an isolation layer located below the adsorption layer and made of an opaque material, the size of the isolation layer being larger than the size of the observation window and smaller than the size of the adsorption layer; and a second release film layer located below the isolation layer and covering the isolation layer.

[0047] First refer to Figure 1 This application describes the structure of the thermal label before and after use. For example... Figure 1As shown, before use, the calorimetric label consists of two independent parts, (a) and (b). Part (a) is the thermosensitive functional layer 1, and part (b) is the adsorption indicator layer 2. The two parts are produced, stored and transported separately. When used, they are combined into one and pasted onto the container or packaging surface of the object to be monitored.

[0048] Viewed from top to bottom along the thickness direction of the calorimeter label, in the thermal functional layer 1, a layer of self-adhesive 12 is coated on the lower surface of the dye substrate layer 10 and then attached to the first sealing film layer 13; a layer of self-adhesive 12 is coated on the lower surface of the first sealing film layer 13 and attached to the first release film layer 14; a layer of sublimable dye is coated on the upper surface of the dye substrate layer 10 to form a sublimable dye layer 11. The first sealing film layer 13 can prevent the sublimable dye from diffusing downwards and contaminating the heat-sensitive item. After the thermal functional layer 1 is manufactured, it is sealed and stored to ensure that the thermal functional layer 1 can be stored and transported at room temperature.

[0049] In the adsorption indicator layer 2, the second sealing film layer 20 uses a transparent material, with a reference color 25 and appropriate product information (such as label model) printed on its upper surface and a circular or square observation window 26 provided as an indicator layer 24, or an independent reference layer with the printed reference color 25 and appropriate product information (such as label model) is attached and formed by die-cutting to form a circular or square observation window 26 as an indicator layer 24; on the lower surface of the second sealing film layer 20, a self-adhesive that can irreversibly adsorb sublimation dye is coated to form an adsorption layer 21, which includes an adsorption indicator area 22; at the location corresponding to the observation window 26, a suitable-sized isolation layer 23 is die-cut and attached to the adsorption layer 21; the second release film layer is located below the isolation layer and covers the isolation layer.

[0050] When using the calorimeter tag, align the isolation layer 23 of the adsorption indicator layer 2 with the sublimation dye layer 11 of the thermosensitive functional layer 1 and attach them together, and the calorimeter tag will start working.

[0051] The working process of the calorimetric label assembly is a continuous process of sublimation-diffusion-adsorption of sublimable dye. Specifically, within a sealed space consisting of a first sealing film layer and a second sealing film layer bonded together by an adsorption layer, the sublimable dye in the sublimable dye layer sublimates upon heating, diffuses through the isolation layer, and is irreversibly adsorbed by the adsorption layer. After the adsorption layer adsorbs the sublimable dye, its color gradually darkens. The color change process of the adsorption layer is observed through an observation window and compared with the endpoint reference color printed around it to determine whether the color change endpoint set by the calorimetric label has been reached, that is, whether the cumulative heat exposure process monitored by the calorimetric label has reached the cumulative heat limit set by the calorimetric label.

[0052] The calorimetric label of this application is essentially a heat-sensitive label. It utilizes the sublimation property of sublimable dyes. With changes in temperature and time (at a certain temperature with the extension of time, or at a certain time with the increase of temperature, or both temperature and time), the sublimable dyes sublimate, causing the color of the adsorption layer to gradually darken. This results in the calorimetric label exhibiting the desired color change effect, thereby determining the cumulative heat exposure status of the monitored object.

[0053] The cumulative heat received by the calorimetric tag in this application is measured and monitored over a period of 7-45 days at 6°C, reflecting the temperature effect of the calorimetric tag's thermal response. 25℃ / 6℃ The value is 7.5 ± 1.0, where Q 25℃ / 6℃ =t 6℃ / t 25℃ , t 6℃ t is the time required for the calorimeter label to reach the optical density (OD) value of the set endpoint color at 6℃. 25℃ The time required for the calorimeter label to reach the optical density (OD) value of the set endpoint color at 25℃, OD = log0 10 (I 入 / I 反 ), I 入 I represents the incident light intensity of the calorimeter tag. 反 This represents the intensity of the reflected light from the calorimeter tag. For example, the number of days the calorimeter tag measures and monitors the cumulative heat received at 6°C can be 7, 10, 15, 17, 20, 24, 28, 30, 35, 40, 45, or a range of any two of these values, where Q is the intensity of the reflected light from the calorimeter tag. 25℃ / 6℃ The values ​​can be 6.5, 6.7, 7.0, 7.2, 7.5, 7.8, 8.0, 8.2, 8.5, or a range of any two values. Therefore, the calorimetric label of this application can be used for monitoring the cumulative heat received over a period of 7-45 days at 6°C in cold chain logistics processes, and can also be used for monitoring the entire lifecycle of heat-sensitive items with a shelf life of 7-45 days at 6°C. Furthermore, it is cost-effective and suitable for storage and transportation conditions.

[0054] Sublimable dyes are key materials determining the cumulative heat range to be measured and monitored by the calorimetric labels in this application. The sublimable dyes used to manufacture the calorimetric labels need to possess suitable color, good chemical and light stability, and appropriate sublimation rate and enthalpy of sublimation to ensure that the thermal response rate, temperature effect, color change amplitude, and thermal response accuracy of the calorimetric labels match the requirements of the monitored object. Specifically, the thermal response rate range of the calorimetric label is mainly determined by the sublimation rate of the sublimable dye, and the temperature effect of the thermal response rate is mainly determined by the enthalpy of sublimation of the sublimable dye.

[0055] Through in-depth research, the inventors discovered that the acetyl-substituted azulene derivatives shown in Formula 1, namely 1-acetyl azulene (R is hydrogen) and 3-methyl-1-acetyl azulene (R is methyl), can be used as sublimation dyes for the calorimetric labels of this application. Using the acetyl-substituted azulene derivatives shown in Formula 1, and matching suitable adsorption and isolation layers to fabricate calorimetric labels, combined with the adjustment of the reference color of the indicator layer, the cumulative heat received by the fabricated calorimetric labels can cover the cumulative heat received at 6°C for 7-45 days as needed, reflecting the temperature effect Q during its thermal response process. 25℃ / 6℃ The value is 7.5 ± 1.0. The calorimetric label provided in this application can be used for monitoring the cumulative heat received during cold chain logistics processes within the range of 7-45 days at 6°C, and also for monitoring the entire life cycle of heat-sensitive items with a shelf life of 7-45 days at 6°C. Therefore, the embodiments of this application all use the acetyl-substituted azulene derivative shown in Formula 1 as a sublimable dye, and its molecular structure can be confirmed by proton nuclear magnetic resonance spectroscopy.

[0056] In some embodiments of this application, the material of the first sealing film layer includes at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid, or nylon. The first sealing film layer can be a transparent film or an opaque film, preferably a white opaque film. The upper surface of the first sealing film layer contains positioning information for the dye substrate layer to facilitate adhesion of the dye substrate layer. In some embodiments, the upper surface of the first sealing film layer also contains label model information. The first sealing film layer can prevent sublimated dyes from diffusing downwards and contaminating heat-sensitive items. This application does not particularly limit the thickness of the first sealing film layer, as long as it achieves the purpose of this application. For example, the thickness of the first sealing film layer can be from 25 μm to 100 μm. In one embodiment, the first sealing film layer uses a 60 μm thick white opaque polypropylene (PP) film.

[0057] In some embodiments of this application, the dye substrate layer includes coated paper, the coated surface of which is bonded to the upper surface of the first sealing film layer by a self-adhesive, including water-based or solvent-based self-adhesive. The coated paper includes at least one of PE coated paper, PET coated paper, or PE / PET coated paper, wherein PE / PET coated paper refers to coated paper simultaneously coated with PE and PET. The PE is in contact with the base paper of the coated paper, which helps to achieve a strong adhesion between the coated surface and the base paper. Coating PET on top of the PE can prevent the penetration of sublimation dyes. This application does not have any particular limitations on the base paper of the coated paper, as long as it achieves the purpose of this application. For example, the base paper of the coated paper can be offset paper or coated paper. The coating thickness and uniformity of the coated paper need to ensure that the attached sublimation dyes cannot penetrate the coating layer. In one embodiment, the dye substrate layer uses 70 g / m³. 2The double-sided adhesive paper has a PE / PET film coated on one side with a film thickness of 12μm. Commercial water-based self-adhesive is used for the self-adhesive, and this application does not have any special restrictions on it, as long as it can achieve the purpose of this application.

[0058] In some embodiments of this application, the first release film layer and the first sealing film layer are bonded together with an adhesive, including water-based or solvent-based adhesives. The material of the first release film layer includes at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid, or nylon. This application does not impose any particular limitation on the thickness of the first release film layer, as long as it achieves the purpose of this application. For example, the thickness of the first release film layer can be from 25 μm to 100 μm. In one embodiment, a 50 μm thick PET release film is used as the first release film layer, and Avery Dennison's S692N water-based adhesive is used.

[0059] In some embodiments of this application, the second sealing film layer is made of a transparent material, including at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid, or nylon. This application does not impose any particular limitation on the thickness of the second sealing film layer, as long as it achieves the purpose of this application. For example, the thickness of the second sealing film layer can be from 25 μm to 100 μm. In one embodiment, the second sealing film layer uses a 50 μm thick biaxially oriented polypropylene (BOPP) transparent film.

[0060] In some embodiments of this application, the indicator layer is formed on the upper surface of the second sealing film layer. Specifically, the upper surface of the second sealing film layer is first printed with a color masking layer using white ink, followed by a reference color for endpoint determination, and an observation window is left in the middle area to form the indicator layer. Forming the indicator layer directly on the second sealing film layer by printing the color masking layer and the reference color helps reduce the materials (e.g., self-adhesive film) and processes used in the preparation of calorimetric labels, thus reducing the preparation cost and the complexity of quality control. In one embodiment, the second sealing film layer uses a 50 μm thick biaxially oriented polypropylene (BOPP) transparent film, and the reference color is printed using Epson's UV-curable digital inkjet printing technology.

[0061] In some embodiments of this application, the indicator layer is an independent reference layer made of a white polymer film. The material of the indicator layer includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid, or nylon. A reference color is printed on the upper surface of the independent reference layer, and an observation window is formed in the middle area of ​​the reference color by die-cutting to form the indicator layer. The lower surface of the indicator layer is bonded to the upper surface of the second sealing film layer with adhesive. Using a white polymer film for the independent reference layer generally provides better masking than a printed white ink masking layer, which helps to reduce the influence of color changes after the adsorption layer absorbs sublimated dyes on the reference color of the indicator layer. This application does not impose any particular limitation on the thickness of the independent reference layer, as long as it achieves the purpose of this application. For example, the thickness of the independent reference layer can be from 25 μm to 100 μm. In one embodiment, the independent reference layer uses a 60 μm thick white opaque polypropylene (PP) film, the adhesive is Avery Dennison AF101 water-based adhesive, and the reference color is printed using EPSON's UV-curing digital inkjet printing technology.

[0062] In some embodiments of this application, the depth of the reference color of the indicator layer around the observation window is the same as the depth of the color presented in the observation window by the adsorption layer due to the adsorption of sublimated dye from the sublimated dye layer after the sublimated dye layer has undergone a set heat exposure process.

[0063] In this application, the process of determining the reference color is as follows: First, the thermosensitive functional layer of the calorimetric label is made using the acetyl-substituted azulene derivative shown in Formula 1, and then it is assembled into a calorimetric label by combining the adsorption indicator layer made with the matching adsorption layer and the isolation layer. After undergoing a set heat exposure process, the adsorption functional layer will show a color change in the observation window of the indicator layer due to the adsorption of sublimated dyes sublimated from the thermosensitive functional layer. The color parameters of the observation window are measured and determined as the color parameters of the indicator endpoint, i.e., the color parameters of the reference color.

[0064] The color parameters in this application are characterized using optical density (OD) values. The optical density value is the ratio of the incident light intensity I... 入 The intensity of reflected light I from the target measurement location on the surface of the calorimeter tag 反 The logarithm of the ratio, i.e.: OD = log 10 (I 入 / I 反 ), where I 入 and I 反Decimal notation is used. In this application, a spectrophotometer is used to measure the optical density value (OD value). Specifically, the spectrophotometer is used to measure the CMYK color gamut OD value of the observation window of the calorimeter label sample. From the measured CMYK color gamut OD values, the color gamut containing the largest OD value is selected as the measurement color gamut, and the OD value of the CMYK color gamut corresponding to the largest OD value in the measurement color gamut is selected as the color parameter of the reference color. This application does not have any particular limitation on the model of the spectrophotometer mentioned above, as long as it can achieve the purpose of this application. For example, the model of the spectrophotometer can be X-Rite 500 and later models, or it can be a Konica-Minolta FD-7 spectrophotometer. Since the area of ​​the optical density measurement region of the calorimeter label is small, it is necessary to ensure that the aperture size of the spectrophotometer measurement hole meets the measurement requirements. The aperture is adjusted and fixed at 2-3 mm by the manufacturer according to the measurement requirements.

[0065] In some implementations, the reference color is determined as follows: A calorimetric label sample is assembled using a produced adsorption indicator layer sample and a finished thermosensitive functional layer. The assembled calorimetric label sample is incubated in a constant temperature water bath at 6±0.2℃. When the calorimetric label sample has been incubated in the constant temperature water bath for a set number of days, the sample is removed, and the CMYK color gamut OD value of the observation window is measured using a spectrophotometer. The color gamut containing the largest OD value from the measured CMYK color gamut OD values ​​is selected as the measurement color gamut. The OD value of the CMYK color gamut corresponding to the largest OD value in the measurement color gamut is selected as the endpoint reference color parameter for the calorimetric label corresponding to the cumulative heat received for the set number of days at 6℃.

[0066] In some embodiments of this application, the adsorption layer itself is formed of transparent self-adhesive, including water-based or solvent-based self-adhesive. The adsorption layer can irreversibly and efficiently adsorb sublimated dyes from the sublimated dye layer and exhibit suitable color change ranges and precision, thereby monitoring the cumulative heat exposure status of heat-sensitive items. In one embodiment, the adsorption layer uses Avery Dennison's S692N water-based self-adhesive.

[0067] In some embodiments of this application, the isolation layer is made of an opaque porous material, including at least one of offset paper or coated paper. The isolation layer material can be a white opaque material or a colored opaque material. The isolation layer has two functions: first, it covers the color of the thermosensitive functional layer, ensuring that the color of the thermosensitive functional layer of the calorimeter label does not affect the color reading of the observation window; second, it provides a diffusion channel for the sublimated dye to diffuse from the thermosensitive functional layer to the adsorption layer after sublimation. Therefore, the isolation layer is preferably a porous material. By using isolation layer materials of different specifications, the thermal response speed of the calorimeter label can be controlled by slightly adjusting the diffusion rate of the sublimated dye. In some embodiments, 60-120 g / m³ is used. 2 White offset paper is used as the release layer material; in other embodiments, 60-120 g / m² is used. 2 White coated paper is used as the isolation layer material.

[0068] In some embodiments of this application, the material of the second release film layer includes at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid, or nylon. The release surface of the second release film layer is adhered to the second sealing film layer via an absorbent layer located on the lower surface of the second sealing film layer and exposed to the outside of the release layer. This application does not impose any particular limitation on the thickness of the second release film layer, as long as it achieves the purpose of this application. For example, the thickness of the second release film layer can be from 25 μm to 100 μm. In one embodiment, a 50 μm thick PET release film is used as the second release film layer.

[0069] In some embodiments of this application, the size of the isolation layer is greater than or equal to the size of the sublimated dye layer. Because the size of the isolation layer is greater than or equal to the size of the sublimated dye layer, the sublimated dye can diffuse completely through the isolation layer to the adsorption layer, and the influence of the sublimated dye layer on the color of the observation window is shielded.

[0070] In some implementations, the size of the observation window is less than the size of the isolation layer, which is less than the size of the adsorption layer. The adsorption layer is larger than the isolation layer, allowing the sublimable dye in the isolation layer to be completely absorbed by the adsorption layer, causing a color change and thus monitoring the cumulative heat exposure status of the heat-sensitive item. The isolation layer is also larger than the observation window, allowing observation of the color change process of the adsorption layer and comparison with the surrounding printed endpoint reference color to determine whether the color change endpoint set on the calorimeter label has been reached, thereby monitoring the cumulative heat exposure status of the heat-sensitive item.

[0071] This application does not impose any particular restrictions on the types of self-adhesive used in the thermal functional layer and adsorption indicator layer of the calorimetric label, as long as they can achieve the purpose of this application after testing. For example, the self-adhesive may include water-based self-adhesive or solvent-based self-adhesive. Water-based self-adhesive may include, but is not limited to, at least one of Avery Dennison's AF101, AR710, S692N, S692NP, S333, or S7200. Solvent-based self-adhesive may include, but is not limited to, at least one of Avery Dennison's DS015, DS128, S8205, or SR36.

[0072] The second aspect of this application provides a method for preparing the calorimetric label provided in the first aspect of this application, comprising the following steps: providing a first sealing film layer; forming a dye substrate layer on the first sealing film layer; forming a sublimable dye layer on the dye substrate layer, the sublimable dye layer containing a sublimable dye, the sublimable dye being an acetyl-substituted azurite derivative as shown in Formula 1: Formula 1, wherein R is hydrogen or methyl; a first release film layer is provided under the first sealing film layer, the dimensions of the first release film layer and the first sealing film layer being larger than the dimensions of the sublimable dye layer, forming a thermosensitive functional layer; and a second sealing film layer formed of a transparent material is provided; an indicator layer is formed on the second sealing film layer, the indicator layer having an observation window and a reference color around the observation window; an adsorption layer is formed under the second sealing film layer, the adsorption layer overlapping or overlapping the observation window in the vertical direction; an isolation layer is formed under the adsorption layer by an opaque material, the size of the isolation layer being larger than the size of the observation window and smaller than the size of the adsorption layer; and a second release film layer is covered under the isolation layer to form an adsorption indicator layer.

[0073] In some embodiments of this application, sublimable dyes are coated or impregnated onto the upper surface of a dye substrate to form a sublimable dye layer. Specifically, the sublimable dye is first dissolved in a solvent to obtain a sublimable dye solution, and the sublimable dye solution is coated or impregnated onto the upper surface of the dye substrate to form a sublimable dye layer. The choice of solvent depends on the solubility of the sublimable dye therein and the environmental requirements of the operation. Commonly used solvents include, but are not limited to, petroleum ether, ethyl acetate, tetrahydrofuran, acetone, etc. This application does not impose specific limitations, as long as the purpose of this application can be achieved. The concentration of the sublimable dye solution is usually between 120-240 g / L. In one embodiment, the acetyl-substituted azulene derivative shown in Formula 1 is quantitatively dissolved in ethyl acetate solvent to form a 180 g / L sublimable dye solution; the sublimable dye solution is placed in an immersion bath, and the dye substrate material is immersed in the sublimable dye solution in the immersion bath. After the solvent evaporates naturally, the sublimable dye adheres to the surface and pores of the dye substrate material to form a sublimable dye layer.

[0074] In some embodiments of this application, a color masking layer is first printed with white ink on the upper surface of the second sealing film layer, and then a reference color for endpoint determination is printed on the color masking layer. An observation window is retained in the middle area of ​​the reference color to form an indicator layer. Printing the color masking layer helps reduce the influence of color changes after the adsorption layer absorbs sublimated dyes on the reference color of the indicator layer. Directly preparing the indicator layer by printing the color masking layer with white ink on the second sealing film layer followed by the reference color reduces the materials (e.g., self-adhesive film) and processes used in the preparation of the calorimetric label, lowering the preparation cost and quality control complexity. In one embodiment, the second sealing film layer uses a 50 μm thick biaxially oriented polypropylene (BOPP) transparent film, and the reference color and color masking layer are printed using EPSON's UV-curable digital inkjet printing technology.

[0075] In some embodiments of this application, a separate reference layer formed of a white polymer film is provided. A reference color is printed on the upper surface of the separate reference layer, and an observation window is formed in the middle area of ​​the reference color by die-cutting. An adhesive is coated on the lower surface of the separate reference layer and adhered to the upper surface of a second sealing film layer to form an indicator layer. The separate reference layer helps to better reduce the influence of color changes after the adsorption layer absorbs sublimated dyes on the reference color of the indicator layer. In one embodiment, the separate reference layer uses a 60 μm thick white opaque polypropylene (PP) film, the adhesive is Avery Dennison's AF101 water-based adhesive, and the reference color is printed using EPSON's UV-curable digital inkjet printing technology.

[0076] The calorimetric label of this application can be mass-produced. According to the method of this application, the production of the calorimetric label is divided into two independent parts: a thermosensitive functional layer and an adsorption indicator layer. It includes the independent processes of preparing the two stacked parts of the thermosensitive functional layer and the adsorption indicator layer, respectively.

[0077] In some implementations, the thermal functional layer is produced by roll-to-roll production, including the following steps: (1) printing thermal functional layer information, including product model and dye substrate layer positioning information, on the upper surface of the first sealing film layer with the release film attached; (2) coating a PE / PET film onto one side of the dye substrate layer material, then coating the coated surface with self-adhesive and attaching it to the PET release film to form the dye substrate layer; (3) quantitatively dissolving the acetyl-substituted azurite derivative shown in Formula 1 in ethyl acetate solvent to form a sublimable dye solution, preferably with a sublimable dye solution concentration range of 120-240 g / L; placing the sublimable dye solution in an immersion bath, immersing the dye substrate layer in the sublimable dye solution in the immersion bath, and after the solvent evaporates naturally, the sublimable dye adheres to the surface and pores of the dye substrate layer material to form a sublimable dye solution. For the dye layer, the preferred dye substrate running speed during dyeing is 3-8m / min; (4) According to the layout of the thermal functional layer printing plate, the dye substrate die-cutting die and the thermal functional layer die-cutting die are customized. The dye substrate is die-cut into the set size on a multi-station rotary die-cutting machine. The preferred dye substrate size is a round piece with a diameter of 5-10mm or a square piece with a side length of 5-10mm. The die-cut dye substrate is positioned and transferred to the upper surface of the first sealing film layer printed with the product model and dye substrate positioning information. Then, the release film attached to the lower surface of the first sealing film layer material is replaced with the first release film layer PET release film; (5) Finally, the thermal functional layer is die-cut into the set size to obtain the finished thermal functional layer. The preferred finished thermal functional layer is a round piece with a diameter of 10-30mm or a square piece with a side length of 10-30mm.

[0078] In some implementations, the thermal functional layer is produced by roll-to-roll manufacturing, including the following steps: (1) printing thermal functional layer information, including product model and dye substrate positioning information, on the first sealing film layer, Avery's BW9319 white self-adhesive film; (2) printing thermal functional layer information, including product model and dye substrate positioning information, on the dye substrate material 70g / m 2One side of the double-sided adhesive paper is coated with a PE / PET film with a thickness of 12μm, and then the coated surface is coated with self-adhesive and then bonded to the PET release film to form a dye substrate layer; (3) The acetyl-substituted azurite derivative shown in Formula 1 is quantitatively dissolved in ethyl acetate solvent to prepare a sublimable dye solution with a concentration of 180g / L; the sublimable dye solution is placed in the dyeing tank, and the dye substrate layer is immersed in the sublimable dye solution in the dyeing tank at a speed of 5m / min. After the solvent evaporates naturally, the sublimable dye adheres to the surface and pores of the dye substrate layer material to form a sublimable dye. Dye layer; (4) According to the layout of the thermal functional layer printing plate, the dye substrate layer die-cutting die and the thermal functional layer die-cutting die are customized. The dye substrate layer is die-cut into a circular piece with a diameter of 5mm on a ten-station circular die-cutting machine, and the position is transferred to the first sealing film layer Avery BW9319 white self-adhesive film printed with the product model and dye substrate positioning information. Then the backing paper of the first sealing film layer BW9319 white self-adhesive film is replaced with the first release film layer PET release film; (5) Finally, the thermal functional layer is die-cut into a circular piece with a diameter of 11mm to obtain the finished thermal functional layer.

[0079] In some implementations, the adsorption indicator layer is produced by roll-to-roll production, including the following steps: (1) applying self-adhesive to the lower surface of the second sealing film layer and attaching release liner to form an adsorption layer; (2) printing indicator layer information, including reference color and product model, on the upper surface of the second sealing film layer, and leaving an observation window in the middle area of ​​the reference color, preferably a round opening with a diameter of 3-8 mm or a square opening with a side length of 3-8 mm; or, providing an independent reference layer, printing indicator layer information, including reference color and product model, on the upper surface of the independent reference layer, and forming an observation window in the middle area of ​​the reference color by die-cutting, preferably a round opening with a diameter of 3-8 mm or a square opening with a side length of 3-8 mm, applying self-adhesive to the lower surface of the independent reference layer and attaching it to the upper surface of the second sealing film to form an indicator layer. (3) According to the layout of the printing plate of the adsorption indicator layer, the isolation layer window die-cutting die, the isolation layer die-cutting die and the adsorption indicator layer die-cutting die are made. On the multi-station rotary die-cutting machine, the isolation layer window is first die-cut on the back paper attached to the second sealing film layer. The preferred size of the isolation layer window is a round opening with a diameter of 6-12mm or a square opening with a side length of 6-12mm. Then the isolation layer material is attached to the isolation layer window and die-cut to form the isolation layer. The preferred size of the isolation layer is a round piece with a diameter of 5-10mm or a square piece with a side length of 5-10mm. (4) The back paper attached to the second sealing film material is replaced with the second release film layer PET release film. (5) Finally, the adsorption indicator layer is die-cut to the set size to obtain the finished adsorption indicator layer. The preferred finished adsorption indicator layer is a round piece with a diameter of 10-30mm or a square piece with a side length of 10-30mm.

[0080] In some implementations, the adsorption indicator layer is produced by roll-to-roll production, including the following steps: (1) printing indicator layer information, including reference color and product model, on the Avery BW9319 white self-adhesive film, which serves as an independent reference layer, and leaving observation window die-cutting positioning information with a diameter of 2.5 mm in the middle area of ​​the reference color; (2) customizing observation window die-cutting die, isolation layer window die-cutting die, isolation layer die-cutting die, and adsorption indicator layer die-cutting die according to the layout of the indicator layer printing plate, and die-cutting the indicator layer on a ten-station rotary die-cutting machine according to the observation window die-cutting positioning information printed on the independent reference layer Avery BW9319 white self-adhesive film to form a straight... (3) Peel off the release paper of the Avery BW9319 white self-adhesive film, which serves as an independent reference layer, and bond it with the face material of the Avery BW0199 transparent self-adhesive film, which serves as the second sealing film layer and the adsorption layer. The face material of the Avery BW0199 transparent self-adhesive film serves as the second sealing film layer, and the self-adhesive layer of the Avery BW0199 transparent self-adhesive film serves as the adsorption layer. (4) Then, position and die-cut the Avery BW0199 transparent self-adhesive film, which serves as the second sealing film layer and the adsorption layer, to form an isolation layer window with a diameter of 6 mm. Then, place the 80 g / m² of the isolation layer into the release paper of the Avery BW0199 transparent self-adhesive film, which serves as the second sealing film layer and the adsorption layer. 2 Double adhesive paper is attached to the window of the isolation layer, and the isolation layer with a diameter of 5mm is positioned and die-cut; (5) the backing paper of the second sealing film layer and the adsorption layer Avery BW0199 transparent self-adhesive film is replaced with the second release film layer PET release film; (6) finally the adsorption indicator layer is die-cut into a round piece with a diameter of 11mm to obtain the finished adsorption indicator layer.

[0081] In this application, the materials of the first sealing film layer, dye substrate layer, and first release film layer in the thermosensitive functional layer, as well as the materials of the second sealing film layer, independent reference layer, adsorption layer, isolation layer, and second release film layer in the adsorption indicator layer, are all commercially available conventional materials. This application does not have any particular restrictions on their sources, as long as they can achieve the purpose of this application.

[0082] This application does not impose any particular restrictions on the preparation method of sublimable dyes, as long as the purpose of this application can be achieved.

[0083] For example, the preparation of the sublimable dye 1-acetylazine may include, but is not limited to, the following steps: cycloheptatrienolone and 4-toluenesulfonyl chloride react in dichloromethane under triethylamine catalysis to obtain intermediate 1; intermediate 1 reacts with dimethyl malonate in methanol under sodium methoxide catalysis to obtain intermediate 2; intermediate 2 reacts with butyraldehyde in ethanol under morpholine and molecular sieve catalysis to obtain methyl 3-ethyl-1-azinecarboxylate; methyl 3-ethyl-1-azinecarboxylate undergoes a 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) dehydrogenation reaction in acetone and water to obtain methyl 3-acetyl-1-azinecarboxylate; methyl 3-acetyl-1-azinecarboxylate is decarboxylated in 100% phosphoric acid to obtain the sublimable dye 1-acetylazine used in this application.

[0084] For example, the preparation of the sublimable dye 3-methyl-1-acetylazine may include, but is not limited to, the following steps: cycloheptatrienolone and 4-toluenesulfonyl chloride react in dichloromethane under triethylamine catalysis to obtain intermediate 1; intermediate 1 reacts with dimethyl malonate in methanol under sodium methoxide catalysis to obtain intermediate 2; intermediate 2 reacts with propionaldehyde in ethanol under morpholine and molecular sieve catalysis to obtain methyl 3-methyl-1-azine carboxylate; methyl 3-methyl-1-azine carboxylate is decarboxylated in 100% phosphoric acid to obtain 1-methylazine; 1-methylazine is reacted in N,N-dimethylacetamide under phosphorus oxychloride catalysis to obtain the sublimable dye 3-methyl-1-acetylazine used in this application.

[0085] The third aspect of this application provides a method for using the calorimetric label provided in the first aspect of this application, comprising the following steps: providing a thermally sensitive functional layer and an adsorption indicator layer of the calorimetric label; removing the second release film layer from the adsorption indicator layer; aligning the isolation layer of the adsorption indicator layer (with the second release film layer removed) with the sublimation dye layer of the thermally sensitive functional layer, and attaching it to the thermally sensitive functional layer to complete the assembly of the calorimetric label; removing the first release film layer of the thermally sensitive functional layer, attaching the assembled calorimetric label to the object to be monitored, and activating the monitoring function of the calorimetric label.

[0086] In some embodiments of this application, the cumulative heat exposure status of the monitored object is determined by observing the color change of the adsorption layer through the observation window of the calorimetric label and comparing it with the reference color. Any of the following three situations will occur: (1) If the color observed through the observation window is lighter than the reference color, it indicates that the cumulative heat exposure of the monitored object is still within the limit set by the calorimetric label; (2) If the color observed through the observation window is the same as the reference color, it indicates that the cumulative heat exposure of the monitored object has reached the limit set by the calorimetric label; (3) If the color observed through the observation window is darker than the reference color, it indicates that the cumulative heat exposure of the monitored object has exceeded the limit set by the calorimetric label.

[0087] In some implementations, the calorimetric label is tested and verified using the following method: A finished product of the thermosensitive functional layer and the adsorption indicator layer of the calorimetric label is provided; the second release film layer in the adsorption indicator layer is removed; the release layer of the adsorption indicator layer (with the second release film removed) is aligned with the sublimable dye layer of the thermosensitive functional layer and attached to the thermosensitive functional layer, completing the assembly of the calorimetric label, which then begins operation; the assembled calorimetric label is placed under set incubation conditions for incubation. After the set incubation time is reached, the calorimetric label is removed, and the reference color and the optical density value of the observation window are measured and compared to determine whether the color change progress of the observation window meets the set requirements. If the difference between the reference color and the optical density value of the observation window is greater than zero at the lower limit of the set incubation time (the minimum number of days for the calorimetric label to reach the set endpoint), and less than zero at the upper limit of the set incubation time (the maximum number of days for the calorimetric label to reach the set endpoint), then the calorimetric label meets the set requirements. Otherwise, the calorimetric label does not meet the set requirements.

[0088] In one embodiment, the assembled calorimetric label is incubated in a 6°C constant-temperature water bath, with the temperature controlled within the range of 6 ± 0.2°C. When the incubation time reaches 7 days (lower limit), the calorimetric label is removed, and the OD values ​​of the reference color and the observation window are measured and recorded, and compared to determine whether the color change progress of the observation window meets the set requirements. After the measurement, it is immediately placed back into the 6°C constant-temperature water bath for continued incubation. When the incubation time reaches 9.33 days (upper limit), the calorimetric label is removed, and the OD values ​​of the reference color and the observation window are measured and recorded, and compared to determine whether the color change progress of the observation window meets the set requirements.

[0089] In one embodiment, the assembled calorimetric label is incubated in a 6°C constant-temperature water bath, with the temperature controlled within the range of 6 ± 0.2°C. When the incubation time reaches 15 days (lower limit), the calorimetric label is removed, and the OD values ​​of the reference color and the observation window are measured and recorded, and compared to determine whether the color change progress of the observation window meets the set requirements. After the measurement, it is immediately placed back into the 6°C constant-temperature water bath for continued incubation. When the incubation time reaches 20 days (upper limit), the calorimetric label is removed, and the OD values ​​of the reference color and the observation window are measured and recorded, and compared to determine whether the color change progress of the observation window meets the set requirements.

[0090] In one embodiment, the assembled calorimetric tag is incubated in a 25°C constant-temperature water bath, with the temperature controlled within the range of 25 ± 0.2°C. When the incubation time reaches 1 day (lower limit), the calorimetric tag is removed, and the OD values ​​of the reference color and the observation window are measured and recorded, and compared to determine whether the color change progress of the observation window meets the set requirements. After the measurement, it is immediately placed back into the 25°C constant-temperature water bath for continued incubation. When the incubation time reaches 1.67 days (upper limit), the calorimetric tag is removed, and the OD values ​​of the reference color and the observation window are measured and recorded, and compared to determine whether the color change progress of the observation window meets the set requirements. In this application, the purpose of incubating the calorimetric tag at 25°C is to combine the results of the incubation experiment at 6°C to obtain the thermal response temperature effect Q of the calorimetric tag of this application. 25℃ / 6℃ value.

[0091] In one embodiment, the assembled calorimetric label is incubated in a 25°C constant-temperature water bath, with the temperature controlled within the range of 25 ± 0.2°C. When the incubation time reaches 2 days (lower limit), the calorimetric label is removed, and the OD values ​​of the reference color and the observation window are measured and recorded, and compared to determine whether the color change progress of the observation window meets the set requirements. After the measurement, it is immediately placed back into the 25°C constant-temperature water bath for continued incubation. When the incubation time reaches 3.33 days (upper limit), the calorimetric label is removed, and the OD values ​​of the reference color and the observation window are measured and recorded, and compared to determine whether the color change progress of the observation window meets the set requirements.

[0092] In some implementations, the thermal response temperature effect of the calorimeter tag is determined by the following method: the calorimeter tag is incubated under two different temperature conditions, and the optical density of the observation window of the calorimeter tag is measured and recorded after incubation for different times; a graph is plotted with incubation time as the x-axis and optical density as the y-axis; the time required for the calorimeter tag to reach the optical density value of the set endpoint color at the two incubation temperatures is found in the graph, and the ratio of the time at the two temperatures reflects the thermal response temperature effect of the calorimeter tag.

[0093] In some implementations, the thermal response temperature effect of the calorimeter tag is determined by the following method: The calorimeter tag is incubated in constant temperature water baths at 6°C and 25°C, respectively, and the OD values ​​of the observation window of the calorimeter tag are measured and recorded after incubation for different times; a graph is plotted with incubation time as the x-axis and optical density as the y-axis; the time t required for the calorimeter tag to reach the set endpoint color at 6°C and 25°C is found in the graph. 6℃ and t 25℃ Calculate the ratio Q of time at the two temperatures. 25℃ / 6℃ =t 6℃ / t 25℃ This ratio reflects the temperature effect of the thermal response of the calorimeter tag.

[0094] The fourth aspect of this application provides a heat-sensitive article using the calorimetric label provided in the first aspect of this application.

[0095] In some embodiments of this application, heat-sensitive items include, but are not limited to, cooked food, beverages, fruits, dairy products (e.g., pasteurized milk and yogurt), fresh meat products, aquatic products, and plasma or blood products for clinical transfusion that require low-temperature storage and transportation.

[0096] Example

[0097] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0098] Example 1: Calorimetric Label Using 1-Acetylazine as a Sublimable Dye

[0099] <Preparation of Sublimation Dyes>

[0100] Step 1: Add 1.24 kg of cycloheptatrienolone and 1.92 kg of 4-toluenesulfonyl chloride to a 10 L reactor, add 5 L of dichloromethane, and add 1.4 L of triethylamine dropwise. React for 2 hours. After the reaction is complete, add an appropriate amount of ice, extract with dichloromethane 4 times, combine the extracts, and dry with anhydrous magnesium sulfate. Filter and rotary evaporate to obtain intermediate 1.

[0101] Step 2: Add 1.1 kg of intermediate 1 to a 25 L reactor, along with 1.15 L of dimethyl malonate and 5 L of methanol. Cool the reaction flask to 0 °C. In another container, add 1.15 L of 30 wt% sodium methoxide and 2 L of methanol. Slowly add the sodium methoxide solution dropwise to the reactor and react at 0 °C for 6 hours. Slowly raise the temperature to room temperature and react overnight. After the reaction is complete, add 5 L of ice water, filter, and wash the precipitate. Vacuum dry overnight to obtain intermediate 2.

[0102] Step 3: Add 1.0 kg of intermediate 2 to a 25 L reactor, add 5 L of anhydrous ethanol and 2 kg of molecular sieve (3A: potassium-A type), mix 1.35 L of butyraldehyde and 1.75 L of morpholine first and then add to the reaction flask, heat to boiling and reflux at 90 °C for 4 hours; after the reaction is completed, treat with silica gel and phosphoric acid to obtain methyl 3-ethyl-1-azinylcarboxylate.

[0103] Step 4: Add 1.07 kg of methyl 3-ethyl-1-azulene carboxylate to a 25 L reactor, along with 10 L of acetone and 1.2 L of water. While stirring, add 2.5 kg of DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) to the reactor in portions, controlling the temperature rise during the reaction to not exceed 20 °C. Stir the reaction at room temperature for 16 hours. After the reaction is complete, filter and wash the precipitate. Dry under vacuum overnight to obtain methyl 3-acetyl-1-azulene carboxylate.

[0104] Step 5: Weigh 3.5 kg of phosphorus pentoxide and add 5.2 L of 85 wt% phosphoric acid to prepare 100% phosphoric acid. Add 5.7 L of the prepared 100% phosphoric acid to a 10 L reactor. Gradually add 1.1 kg of methyl 3-acetyl-1-azinylcarboxylate to the reactor, controlling the temperature to not exceed 100 °C. Stir the reaction at 100 °C for 4 hours until no more bubbles appear, then stop the reaction. Treat with silica gel, extract with ethyl acetate, wash with alkali, and rotary evaporate to obtain the sublimation dye 1-acetylazinyl used in this application.

[0105] The prepared sublimable dye was confirmed to be 1-acetylazine by 1H NMR spectroscopy, such as Figure 2 As shown.

[0106] <Preparation of the thermosensitive functional layer>

[0107] Information about the thermal functional layer, including the product model and the positioning information of the dye substrate layer, is printed on the first sealing film layer, Avery Dennison BW9319 white self-adhesive PP film with a thickness of 60μm.

[0108] 70g / m of dye substrate material 2 A PE / PET film with a thickness of 12μm is formed by coating one side of the double-sided adhesive paper, and then water-based self-adhesive is coated on the coated side and bonded to the PET release film to form a dye substrate layer.

[0109] The prepared sublimable dye was quantitatively dissolved in ethyl acetate solvent to form a sublimable dye solution of 180 g / L. The sublimable dye solution was placed in an immersion tank, and the dye substrate material was immersed in the sublimable dye solution in the immersion tank at a speed of 5 m / min. After the solvent evaporated naturally, the sublimable dye adhered to the surface and pores of the dye substrate material to form a sublimable dye layer.

[0110] Based on the layout of the thermal functional layer printing plate, a custom-made die-cutting mold for the dye substrate layer and a die-cutting mold for the thermal functional layer are made. The dye substrate layer is die-cut into a circular piece with a diameter of 5mm on a ten-station rotary die-cutting machine. The piece is then positioned and transferred onto the first sealing film layer, Avery BW9319 white self-adhesive PP film, which is printed with the product model and dye substrate positioning information. The backing paper of the first sealing film layer, Avery BW9319 white self-adhesive PP film, is then replaced with a first release film layer, PET release film, with a thickness of 50μm.

[0111] The thermal functional layer is die-cut into a circular piece with a diameter of 11mm to obtain the finished thermal functional layer.

[0112] <Preparation of Adsorption Indicator Layer>

[0113] Indicator information, including reference color and product model, is printed on a 60μm thick Avery BW9319 white self-adhesive PP film used as an independent reference layer. A 2.5mm diameter observation window is left in the middle area of ​​the reference color for die-cutting positioning information.

[0114] Based on the layout of the indicator layer printing plate, custom-made die-cutting dies for the observation window, the isolation layer window, the isolation layer, and the adsorption indicator layer are used. On a ten-station rotary die-cutting machine, the observation window with a diameter of 3mm is die-cut according to the die-cutting positioning information printed on the independent reference layer BW9319 white self-adhesive PP film, thus forming the indicator layer.

[0115] The release liner of the Avery BW9319 white self-adhesive PP film, which serves as an independent reference layer, is peeled off and bonded to the face material of the Avery BW0199 transparent self-adhesive BOPP film material, which has a thickness of 50μm. The face material of the Avery BW0199 transparent self-adhesive film material serves as the second sealing film layer, and the self-adhesive layer of the Avery BW0199 transparent self-adhesive film material serves as the adsorption layer.

[0116] A 6mm diameter isolation layer window is formed by die-cutting on the backing paper of the second sealing film layer and the absorbent layer Avery BW0199 transparent self-adhesive BOPP film material. Then, an 80g / m³ isolation layer is applied. 2 Double-sided adhesive paper is attached to the window of the isolation layer, and then die-cut to form an isolation layer with a diameter of 5mm.

[0117] Replace the backing paper of the second sealing film layer and the absorbent layer Avery BW0199 transparent self-adhesive BOPP film with a second release film layer of PET release film with a thickness of 50μm.

[0118] The adsorption indicator layer is die-cut into a circular piece with a diameter of 11 mm to obtain the finished adsorption indicator layer.

[0119] Example 2: Calorimetric Label Using 3-Methyl-1-acetylazine as a Sublimable Dye

[0120] Except for the preparation method used in <Preparation of Sublimation Dyes>, the rest is the same as in Example 1.

[0121] <Preparation of Sublimation Dyes>

[0122] Step 1: Add 1.0 kg of intermediate 2 synthesized in Example 1 to a 25 L reactor, add 5 L of anhydrous ethanol and 2.0 kg of molecular sieve (3A: potassium-A type), and add 1.15 L of propionaldehyde and 1.75 L of morpholine to the reactor. Heat to boiling and reflux at 90 °C for 4 hours.

[0123] The product was treated with silica gel, filtered, and eluted with petroleum ether. The filtrate and eluent were collected and concentrated by rotary evaporation. The product was treated with 1 mol / L phosphoric acid solution and washed with water. The organic phase was removed by rotary evaporation, and the product was crystallized with water and filtered to obtain the blue-purple crystalline product methyl 3-methyl-1-azoocarboxylate.

[0124] Step 2: Weigh 3.5 kg of phosphorus pentoxide and add 5.2 L of 85 wt% phosphoric acid to prepare 100% phosphoric acid. Add 5.7 L of the prepared 100% phosphoric acid to a 10 L reactor. Gradually add 1.0 kg of methyl 3-methyl-1-azinylcarboxylate to the reactor, controlling the reaction temperature to not exceed 100 °C. Stir the reaction at 100 °C for 3 hours until no more bubbles appear, then stop the reaction. Treat with silica gel, extract with ethyl acetate, wash with alkali, and rotary evaporate to obtain 1-methylazinylcarboxylate.

[0125] Step 3: Add 0.71 kg of 1-methylazine to a 10 L reactor, add 1.25 L of N,N-dimethylacetamide and 0.57 L of phosphorus oxychloride, and heat under reflux for 24 hours; treat with silica gel, filter, and elute with petroleum ether; collect the filtrate and eluent, concentrate by rotary evaporation; treat with 1 mol / L phosphoric acid solution, wash with water; remove petroleum ether from the organic phase by rotary evaporation, crystallize with water, and filter to obtain the sublimable dye 3-methyl-1-acetylazine used in this application.

[0126] The prepared sublimable dye was confirmed by 1H NMR spectroscopy to be 3-methyl-1-acetylazine, such as... Figure 3 As shown.

[0127] Comparative Example 1: Calorimetric label using methyl 1-azurate as a sublimable dye

[0128] Except for the preparation method used in <Preparation of Sublimation Dyes>, the rest is the same as in Example 1.

[0129] <Preparation of Sublimation Dyes>

[0130] 1.0 kg of intermediate 2 synthesized in Example 1 was added to a 25 L reactor, 1.8 L of acetaldehyde was added to a container containing 10 L of diethylamine, and the mixture was added to the reactor containing intermediate 2. The mixture was refluxed for 4 hours.

[0131] The reaction mixture was removed by rotary evaporation to remove acetaldehyde and diethylamine; the mixture was dissolved in petroleum ether; the mixture was filtered through silica gel and eluted with petroleum ether; the filtrate and eluent were collected and concentrated by rotary evaporation; the mixture was treated with 1 mol / L phosphoric acid solution and washed with water; the organic phase was removed by rotary evaporation to remove petroleum ether, yielding a purplish-red crystalline product, methyl 1-azinecarboxylate, i.e., the azulene derivative shown in Formula 2 (R=H).

[0132] Formula 2

[0133] Comparative Example 2: Calorimetric label using methyl 3-methyl-1-azolecarboxylate as a sublimable dye

[0134] Except for the preparation method used in <Preparation of Sublimation Dyes>, the rest is the same as in Example 1.

[0135] <Preparation of Sublimation Dyes>

[0136] The blue-purple crystalline product methyl 3-methyl-1-azinol carboxylate, i.e., the azurite derivative shown in Formula 2 (R=CH3), was prepared according to step 1 of Example 2.

[0137] Formula 2

[0138] Test methods and equipment :

[0139] Q of thermal response temperature effect 25℃ / 6℃ Value testing

[0140] Remove the second release film layer from the adsorption indicator layer of the calorimetric labels in each embodiment and comparative example; align the isolation layer of the adsorption indicator layer with the second release film layer removed with the sublimation dye layer of the thermosensitive functional layer, and attach it to the thermosensitive functional layer to complete the assembly of the calorimetric label, and the calorimetric label will then start working.

[0141] The assembled calorimetric label samples were divided into two groups of 20 each. The two groups were incubated in constant-temperature water baths at 6±0.2℃ and 25±0.2℃, respectively. The calorimetric label samples were removed at different incubation time points, and the CMYK color gamut OD value of the observation window of the calorimetric label sample was measured using a spectrophotometer. After the measurement, the calorimetric label samples were returned to the constant-temperature water bath for further incubation. The maximum OD value was selected from the measured CMYK color gamut OD values, and its corresponding color gamut was used as the measurement color gamut. A graph was plotted with incubation time on the x-axis and the maximum OD value on the y-axis. The time required for the calorimetric label to reach the set endpoint color at 6℃ and 25℃ was found in the graph, and the average value of the 20 calorimetric labels was calculated as t. 6℃ and t 25℃ Further calculations yielded the ratio Q of time at the two temperatures. 25℃ / 6℃ =t 6℃ / t 25℃ This ratio reflects the temperature effect of the thermal response of the calorimeter tag.

[0142] Figure 4 This is a graph showing the change of the OD value of the observation window with incubation time when the calorimetric label of Embodiment 1 of this application is incubated at 6°C. Figure 5 This is a graph showing the change in the OD value of the observation window as a function of incubation time when the calorimetric label of Embodiment 1 of this application is incubated at 25°C. Figure 4 and Figure 5 As can be seen, the sublimation dye selected is 1-acetylazine, and when the OD value is 0.5, t 6℃ =7 days, t 25℃ =0.9 days, Q 25℃ / 6℃ =t 6℃ / t 25℃ =7.8; when the OD value is 0.75, t 6℃ =15 days, t 25℃ =1.9 days, Q 25℃ / 6℃ =t 6℃ / t 25℃ =7.9; when the OD value is 0.85, t 6℃ =21 days, t 25℃ =2.5 days, Q 25℃ / 6℃ =t 6℃ / t 25℃ =8.4.

[0143] Figure 6 This is a graph showing the change of OD value of the observation window with incubation time when the calorimetric label of Embodiment 2 of this application is incubated at 6°C. Figure 7 This is a graph showing the change in the OD value of the observation window as a function of incubation time when the calorimetric label of Embodiment 2 of this application is incubated at 25°C. Figure 6 and Figure 7As can be seen, the sublimation dye selected is 3-methyl-1-acetylazine, and when the OD value is 0.57, t 6℃ =15 days, t 25℃ =2.0 days, Q 25℃ / 6℃ =t 6℃ / t 25℃ =7.5; when the OD value is 0.65, t 6℃ =21 days, t 25℃ =2.8 days, Q 25℃ / 6℃ =t 6℃ / t 25℃ =7.5; when the OD value is 0.77, t 6℃ =28 days, t 25℃ =3.8 days, Q 25℃ / 6℃ =t 6℃ / t 25℃ =7.4; when the OD value is 0.85, t 6℃ =35 days, t 25℃ =4.5 days, Q 25℃ / 6℃ =t 6℃ / t 25℃ =7.8; when the OD value is 1.0, t 6℃ =45 days, t 25℃ =6.5 days, Q 25℃ / 6℃ =t 6℃ / t 25℃ =6.9.

[0144] Figure 8 This is a graph showing the change in the OD value of the observation window as a function of incubation time when the calorimetric label of Comparative Example 1 of this application is incubated at 25°C. From... Figure 8 As can be seen, methyl 1-azonocarboxylate was selected as the sublimation dye. When the OD value is 0.72, t 25℃ =5 days; when the OD value is 0.76, t 25℃ =6 days; when the OD value is 0.88, t 25℃ =8 days; when the OD value is 1.0, t 25℃ =10 days; when the OD value is 1.08, t 25℃ =12 days.

[0145] Figure 9 This is a graph showing the change in the OD value of the observation window as a function of incubation time when the calorimetric label of Comparative Example 2 of this application is incubated at 25°C. From... Figure 9 As can be seen, the sublimation dye selected is methyl 3-methyl-1-azonocarboxylate. When the OD value is 0.7, t 25℃ =21 days; when the OD value is 0.75, t 25℃ =25 days; when the OD value is 0.8, t 25℃ =30 days; when the OD value is 0.85, t25℃ =35 days; when the OD value is 0.9, t 25℃ =40 days; when the OD value is 0.94, t 25℃ =45 days.

[0146] The calorimetric labels provided in this application all require a response time to reach the endpoint at at least two temperatures, or a response time to reach the endpoint at one temperature and a Q value reflecting the temperature effect of its thermal response. These are two key product parameters characterizing the calorimetric label (in some embodiments, the response time to reach the endpoint at two temperatures; in other embodiments, the response time to reach the endpoint at one temperature and a Q value reflecting the temperature effect of its thermal response). If either of these two key product parameters differs, it represents a different calorimetric label product, which will be applied to different monitoring objects. These two key product parameters are mainly controlled by the sublimation performance (sublimation rate and sublimation enthalpy) of the sublimable dye used. The applicant of this application currently mainly develops calorimetric label products based on azurite derivatives as sublimable dyes. The key technology is to utilize the substituents of azurite derivatives to control their sublimation performance in order to obtain calorimetric label products with the target product parameters.

[0147] The sublimation dyes used in Examples 1 and 2 of this application are acetyl-substituted azulene derivatives as shown in Formula 1, namely 1-acetyl azulene (R is hydrogen) and 3-methyl-1-acetyl azulene (R is methyl). The calorimetric label used to fabricate the label can monitor the cumulative heat received over a period of 7-45 days at 6°C, reflecting the temperature effect of the thermal response process, Q. 25℃ / 6℃ The value is 7.5±1.0. Therefore, the calorimetric label provided in this application can be used for monitoring the cold chain logistics process within the cumulative heat received in the range of 7-45 days at 6℃, and can also be used for monitoring the entire life cycle of heat-sensitive items with a shelf life of 7-45 days at 6℃, and the cost is low.

[0148] Patent CN 201710222789.9 discloses a calorimetric labels that use azulene derivatives as shown in Formula 2 as sublimation dyes, namely methyl 1-azonocarboxylate and methyl 3-methyl-1-azonocarboxylate. Comparative Examples 1 and 2 show the thermal response results of calorimetric labels made using these two azulene derivatives incubated at 25°C: the calorimetric label using methyl 1-azonocarboxylate reached the endpoint in 5-12 days. Figure 8 The time to reach the endpoint using the calorimetric label of methyl 3-methyl-1-azole was between 21 and 45 days. Figure 9 Q, which reflects the temperature effect during its thermal response process. 37℃ / 25℃ The value is 4.5-5.0, from which its Q can be calculated. 25℃ / 6℃The values ​​were 10.8-12.8, corresponding to response times of 54-154 days and 227-576 days at 6°C, respectively. Therefore, the calorimetric label disclosed in patent CN201710222789.9 requires less time to reach the endpoint after incubation at 6°C than the one using 1-acetylazine in this application (7-21 days). Figure 4 ) and 3-methyl-1-acetylazine (15-45 days, Figure 6 The product's lifespan is significantly extended, making it unable to cover the cumulative heat exposure over 7-45 days at 6°C. Therefore, it cannot be used for monitoring cold chain logistics processes within the cumulative heat exposure range of 7-45 days at 6°C, or for monitoring the entire life cycle of heat-sensitive items with a shelf life of 7-45 days at 6°C.

[0149] Figure 10 This is a diagram illustrating the color change of the calorimetric label in use according to Embodiment 1 of this application. The reference color of the calorimetric label is set with a lower limit of 7 days and an upper limit of 9.33 days for reaching the endpoint at 6°C. At 6°C, when the incubation period is 2.3 days (marked as 33% in the figure) and 4.7 days (marked as 67% in the figure), the color of the observation window is significantly lighter than the reference color, reflecting that the cumulative heat exposure of the monitored object is still within the limits set by the calorimetric label. When the incubation period is 7 days (marked as 100% in the figure, corresponding to the lower limit of the response time), the color of the observation window is slightly lighter than the reference color but very close, reflecting that the cumulative heat exposure of the monitored object is very close to the limits set by the calorimetric label. When the incubation period is 9.33 days (marked as 133% in the figure, corresponding to the upper limit of response time), 11.7 days (marked as 167% in the figure), and 14 days (marked as 200% in the figure), the color of the observation window is darker than the reference color, reflecting that the cumulative heat exposure of the monitored object of the calorimetric label has exceeded the limit set by the calorimetric label.

[0150] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0151] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0152] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A calorimetric label for monitoring cold chain logistics processes, comprising two stacked layers that are physically independent of each other before use: a thermally sensitive functional layer and an adsorption indicator layer, wherein... The thermal functional layer includes: First sealing membrane layer; A dye substrate layer is formed on top of the first sealing film layer; A sublimable dye layer is formed on the dye substrate layer, the sublimable dye layer containing a sublimable dye, the sublimable dye being an acetyl-substituted azulene derivative as shown in Formula 1: Formula 1, where R is hydrogen or methyl; A first release film layer is located below the first sealing film layer, and the dimensions of the first release film layer and the first sealing film layer are larger than the dimensions of the sublimable dye layer; as well as The adsorption indicator layer includes: The second sealing membrane layer is made of a transparent material; An indicator layer, which is located above the second sealing film layer and has an observation window, with a reference color around the observation window; An adsorption layer is located below the second sealing film layer, and the adsorption layer overlaps or overlaps with the observation window in the vertical direction; An isolation layer, located beneath the adsorption layer and made of an opaque material, is larger than the size of the observation window but smaller than the size of the adsorption layer. A second release film layer is located below the isolation layer and covers the isolation layer.

2. The calorimetric label according to claim 1, wherein, The cumulative heat received by the calorimetric tag is measured and monitored over a period of 7-45 days at 6°C, reflecting the temperature effect of the calorimetric tag's thermal response. 25℃ / 6℃ The value is 7.5 ± 1.0, where Q 25℃ / 6℃ =t 6℃ / t 25℃ , t 6℃ t is the time required for the calorimetric label to reach the optical density (OD) value of the set endpoint color at 6°C. 25℃ The time required for the calorimetric label to reach the optical density (OD) value of the set endpoint color at 25°C is given by OD = log0. 10 (I 入 / I 反 ), I 入 I is the incident light intensity of the calorimetric label. 反 The intensity of the reflected light from the calorimetric label.

3. The calorimetric label according to claim 1, wherein, The upper surface of the first sealing film layer contains the positioning information of the dye substrate layer.

4. The calorimetric label according to claim 1, wherein, The dye substrate layer includes a coated paper, and the coated surface of the coated paper is bonded to the first sealing film layer by an adhesive, wherein the adhesive includes water-based adhesive or solvent-based adhesive.

5. The calorimetric label according to claim 1, wherein, The first release film layer and the first sealing film layer are bonded together with self-adhesive, which includes water-based self-adhesive or solvent-based self-adhesive.

6. The calorimetric label according to claim 1, wherein, The indicator layer is formed on the second sealing film layer and is located on the upper surface of the second sealing film layer.

7. The calorimetric label according to claim 1, wherein, The indicator layer is an independent reference layer made of a white polymer film. The material of the indicator layer includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid, or nylon. The indicator layer is bonded to the second sealing film layer with an adhesive.

8. The calorimetric label according to claim 1, wherein, The depth of the reference color of the indicator layer around the observation window is the same as the depth of the color of the adsorption layer in the observation window after the sublimated dye layer has undergone a set heat exposure process, due to the adsorption of sublimated dye from the sublimated dye layer.

9. The calorimetric label according to claim 1, wherein, The adsorption layer itself is formed of transparent self-adhesive, including water-based self-adhesive or solvent-based self-adhesive.

10. The calorimetric label according to claim 1, wherein, The insulating layer is made of an opaque porous material, including at least one of offset paper or coated paper.

11. The calorimetric label according to claim 1, wherein, The materials of the first sealing film layer and the second sealing film layer each independently include at least one of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid or nylon.

12. The calorimetric label according to claim 1, wherein, The materials of the first release film layer and the second release film layer each independently include at least one of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polylactic acid or nylon.

13. The calorimetric label according to claim 1, wherein, The size of the isolation layer is greater than or equal to the size of the sublimation dye layer.

14. A method for preparing a calorimetric label as described in any one of claims 1 to 13, comprising the following steps: Provide a first sealing membrane layer; A dye substrate layer is formed on the first sealing film layer; A sublimable dye layer is formed on the dye substrate layer, the sublimable dye layer containing a sublimable dye, the sublimable dye being an acetyl-substituted azurite derivative as shown in Formula 1: Formula 1, where R is hydrogen or methyl; A first release film layer is provided under the first sealing film layer, and the dimensions of the first release film layer and the first sealing film layer are larger than the dimensions of the sublimable dye layer, forming a thermosensitive functional layer; as well as Provide a second sealing film layer formed of a transparent material; An indicator layer is formed on the second sealing film layer, the indicator layer having an observation window and a reference color around the observation window; An adsorption layer is formed under the second sealing film layer, and the adsorption layer overlaps or overlaps with the observation window in the vertical direction; An isolation layer is formed beneath the adsorption layer by an opaque material. The size of the isolation layer is larger than the size of the observation window but smaller than the size of the adsorption layer. A second release film layer is covered under the isolation layer to form an adsorption indicator layer.

15. The preparation method according to claim 14, wherein, The sublimable dye is applied to the upper surface of the dye substrate layer by coating or impregnation to form the sublimable dye layer.

16. The preparation method according to claim 14, wherein, On the upper surface of the second sealing film layer, a color masking layer is first printed with white ink, and then a reference color is printed on the color masking layer. An observation window is reserved in the middle area of ​​the reference color to form the indicator layer.

17. The preparation method according to claim 14, wherein, A separate reference layer formed of a white polymer film is provided, a reference color is printed on the upper surface of the separate reference layer, and an observation window is formed by die-cutting in the middle area of ​​the reference color. An adhesive is coated on the lower surface of the separate reference layer and bonded to the second sealing film layer to form the indicator layer.

18. A method of using a calorimetric label as described in any one of claims 1 to 13, comprising the following steps: The calorimetric label is provided with a thermosensitive functional layer and an adsorption indicator layer; Remove the second release film layer from the adsorption indicator layer; Align the isolation layer of the adsorption indicator layer (with the second release film removed) with the sublimation dye layer of the thermosensitive functional layer, and attach it to the thermosensitive functional layer to complete the assembly of the calorimetric label. Remove the first release film layer of the thermal functional layer, attach the assembled calorimetric tag to the object to be monitored, and activate the monitoring function of the calorimetric tag.

19. The method of use according to claim 18, wherein, By observing the color change of the adsorption layer through the observation window of the calorimetric tag and comparing it with a reference color, the cumulative heat exposure status of the object monitored by the calorimetric tag is determined, and any of the following three situations will occur: If the color observed through the observation window is lighter than the reference color, it indicates that the cumulative heat exposure of the monitored object by the calorimetric label is still within the limit set by the calorimetric label. If the color observed through the observation window is the same as the reference color, it indicates that the cumulative heat exposure of the monitored object of the calorimetric label has reached the limit set by the calorimetric label. If the color observed through the observation window is darker than the reference color, it indicates that the cumulative heat exposure of the monitored object by the calorimetric label has exceeded the limit set by the calorimetric label.

20. A heat-sensitive article using the calorimetric label according to any one of claims 1 to 13.

21. The heat-sensitive article according to claim 20, wherein, The heat-sensitive items include cooked food, beverages, fruits, dairy products, fresh meat products, aquatic products, and plasma or blood products used for clinical transfusion that require low-temperature storage and transportation.

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