Irreversible temperature change indicator and preparation method thereof

Abstract

The present invention relates to an irreversible temperature indicator. When applied to equipment such as precision instruments and power cables, if localized overheating or short-circuit overheating occurs, the irreversible temperature indicator will display a corresponding color. This reduces the complexity of the overall search process and reduces safety concerns for personnel involved in troubleshooting high-voltage equipment. Furthermore, the irreversible temperature indicator provided by this application is simple to operate and has a broad market application.

Description

Technical Field

[0001] The present invention relates to the technical field of indicator devices, and in particular to an irreversible temperature change indicator and a preparation method thereof. Background Art

[0002] High-temperature monitoring provides real-time insights into the operational status of equipment and components, and records the high-temperature environments they have been exposed to. This provides users with information on the temperature conditions experienced by the equipment and components, allowing them to assess their suitability and durability, thereby ensuring they remain in normal operation. High-temperature monitoring has been widely adopted in fields such as precision instruments and power systems. The following describes common methods for high-temperature cable monitoring.

[0003] There is a kind of SPYBALL capsule powder on the market. After the powder is applied to the cable, the color of the coated part will disappear when the cable outlet is locally overheated. However, the color of the SPYBALL capsule powder will gradually recover after the cable outlet temperature drops below 0°C. It is a reversible temperature change indicator material. When the reversible temperature indicator material exceeds the operating temperature range, it cannot accurately reflect whether the cable outlet has been in an overheated temperature condition, which limits its application. Summary of the Invention

[0004] This application mainly solves the problem that the current reversible temperature change indicator material cannot accurately reflect whether the monitored object has been in an overheated temperature condition.

[0005] To achieve the above objectives, this application is implemented through the following technical solutions.

[0006] The present application provides an irreversible temperature change indicator, comprising a base layer and a functional layer that are stacked together. The functional layer becomes irreversibly transparent when the temperature reaches a predetermined temperature, and is used to display the color of the base layer.

[0007] As a further improvement of the present application, the functional layer includes a stacked phase change layer and an absorption layer, and the absorption layer is arranged on at least one surface of the phase change layer; the phase change layer undergoes a phase change after the temperature reaches a predetermined temperature to present a transparent state and releases a first substance; the absorption layer is used to absorb the first substance released after the phase change layer undergoes a phase change and presents a transparent state.

[0008] As a further improvement of the present application, the phase change layer is formed by solidifying a temperature-changing slurry, the temperature-changing slurry includes temperature-changing microcapsules and additives, the temperature-changing microcapsules include a first substance and a wall material that seals the first substance, the wall material is made of a temperature-changing material, and the temperature-changing material causes the phase change layer to undergo a phase change after the temperature reaches a predetermined temperature, so that the wall material of the temperature-changing microcapsule ruptures and releases the first substance.

[0009] As a further improvement of the present application, the temperature-variable material is one or more of polymethyl methacrylate, polyisocyanate, polyurea, and polyamide.

[0010] As a further improvement of the present application, the first substance is silicone oil; and the absorption layer is paper.

[0011] As a further improvement of the present application, a protective layer is further provided on the side of the functional layer away from the base layer.

[0012] As a further improvement of the present application, the base layer includes a release layer, an adhesive layer and a base color layer stacked in sequence, the base color layer is arranged below the functional layer so that the functional layer becomes transparent and displays color after the temperature reaches a predetermined temperature; the adhesive layer is arranged below the base color layer so that the irreversible temperature change indicator is attached to the object to be tested; the release layer is detachably arranged below the adhesive layer.

[0013] As a further improvement of the present application, the base color layer is prepared from a colored slurry, and the colored slurry includes an inorganic pigment, and the inorganic pigment is any one or more of chrome yellow, iron blue, cadmium red, cadmium yellow, lithopone, carbon black, iron oxide red, and iron oxide yellow.

[0014] As a further improvement of the present application, the adhesive layer is a double-sided tape, and the double-sided tape is prepared from a single component or multiple components. The single component is any one of white oil glue, yellow hot melt glue, water glue, and embroidery glue, and the multiple components are at least two of white oil glue, yellow hot melt glue, water glue, and embroidery glue.

[0015] As a further improvement of the present application, the auxiliary agent includes a water-based resin, and the auxiliary agent also includes at least one of a dispersant, a leveling agent, a defoaming agent, and a thickener.

[0016] To achieve the above-mentioned purpose, the present application also provides a method for preparing an irreversible temperature change indicator. The irreversible temperature change indicator includes a base layer and a functional layer. The irreversible temperature change indicator is prepared by the following method: the functional layer is stacked on the base layer, and the functional layer becomes transparent after the temperature reaches a predetermined temperature, so as to display the color of the base layer.

[0017] As a further improvement of the present application, the base layer includes a release layer, an adhesive layer and a base color layer, and the base layer is prepared by the following method: uniformly spraying an adhesive material on any surface of the release layer to achieve stacking an adhesive layer on the release layer; uniformly spraying a colored slurry on the surface of the adhesive layer away from the release layer to achieve stacking an base color layer on the adhesive layer.

[0018] As a further improvement of the present application, the functional layer is stacked on the base color layer, and the functional layer includes a phase change layer. The phase change layer is prepared by the following method: S1, preparing a temperature-changing slurry; S2, uniformly coating the temperature-changing slurry into a film and then curing it to form a phase change layer.

[0019] As a further improvement of the present application, the functional layer also includes an absorption layer, and the absorption layer is prepared by the following method: when the absorption layer only includes a first absorption layer located between the base color layer and the phase change layer: first prepare the first absorption layer on the base color layer, and then uniformly apply the temperature-changing slurry on the first absorption layer and solidify it to form a phase change layer; or; when the absorption layer only includes a second absorption layer located on the surface of the phase change layer away from the base color layer: directly prepare the second absorption layer on the surface of the phase change layer away from the base color layer; or; when the absorption layer includes a first adsorption layer located between the base color layer and the phase change layer and a second adsorption layer located on the surface of the phase change layer away from the base color layer: first prepare the first absorption layer on the base color layer, and then uniformly apply the temperature-changing slurry on the first absorption layer and solidify it to form a phase change layer, and prepare the second absorption layer on the surface of the phase change layer away from the base color layer.

[0020] The beneficial effect of this application is that it provides an irreversible temperature indicator. When applied to equipment such as precision instruments and power cables, if localized high temperature or short-circuit overheating occurs, the irreversible temperature indicator will display a corresponding local color. This not only reduces the complexity of the overall search process but also reduces the safety concerns for personnel involved in high-voltage equipment during the troubleshooting process. Furthermore, the irreversible temperature indicator provided by this application is simple to operate and has a broad market application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of state 1 of the irreversible temperature change indicator of the present application;

[0022] In the figure: 1. Base layer; 2. Functional layer; 3. Protective layer;

[0023] 11. Release layer; 12. Adhesive layer; 13. Base color layer; 21. Phase change layer; 22. Absorption layer. DETAILED DESCRIPTION

[0024] To make the purpose, technical solutions and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments and drawings of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them, and are not intended to limit the scope of the invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0025] The present application provides an irreversible temperature change indicator, comprising a stacked base layer 1 and a functional layer 2. The functional layer 2 becomes irreversibly transparent upon reaching a predetermined temperature, thereby displaying the color of the base layer 1. When the irreversible temperature change indicator is applied to a cable, the irreversible temperature change indicator will display the color of the base layer 1 when the ambient temperature of the cable is not lower than the predetermined temperature of the irreversible temperature change indicator. The color of the irreversible temperature change indicator will remain permanently, making it easier for cable users to observe.

[0026] The inventors discovered that 3M has developed a thermochromic tape. When applied to key nodes in a power system, this tape will irreversibly change color when overheated. For example, the power connector disclosed in Chinese patent CN207197695U has a thermochromic functional layer 2 disposed on the surface of the power connector body. This thermochromic layer can be a single layer made of a pigment that changes color at different temperatures, or it can be a multilayer structure, such as a layer formed of a normal pigment and a wax layer that melts at a predetermined temperature on top of the normal pigment layer. When the wax melts at the predetermined temperature, the color of the underlying pigment layer is revealed. The inventors conducted experiments on color-changing tapes made with this thermochromic layer and found that the color development of this tape has a certain disadvantage: the color development has a time lag. When a cable outlet is locally overheated, it takes at least an hour or more for the color-changing tape to change from colorless to noticeable color, making it impossible to make an immediate judgment. Furthermore, the present application provides a functional layer 2 comprising a stacked phase change layer 21 and an absorption layer 22, with the absorption layer 22 disposed on at least one surface of the phase change layer 21. Upon reaching a predetermined temperature, the phase change layer 21 undergoes a phase change to become transparent and releases a first substance. The absorption layer 22 is configured to absorb the first substance released by the phase change layer 21 and thereby become transparent. When the irreversible temperature change indicator of the present application is applied to a cable, the functional layer 2 becomes transparent primarily through the phase change of the phase change layer 21 upon reaching a predetermined temperature, and the absorption layer 22 absorbs the first substance released by the phase change layer. This, in turn, reveals the color of the base layer 1, ultimately indicating the high temperature state of the cable through the irreversible temperature change indicator. Compared to the color change reaction time of color-changing pigments and the time it takes for wax to absorb heat and become transparent, the phase change is much faster. When exposed to high temperatures, the irreversible temperature change indicator of the present application changes color in a maximum of 10 seconds, with no color retention. The irreversible temperature-changing indicator prepared by the functional layer 2 has a fast phase transition speed, so that the entire irreversible temperature-changing indicator has a fast color development speed and excellent color development performance.

[0027] As a preferred embodiment, the phase change layer 21 is formed by solidifying a temperature-changing slurry, wherein the temperature-changing slurry includes temperature-changing microcapsules and an additive, wherein the temperature-changing microcapsules include a first substance and a wall material that seals the first substance, wherein the wall material is made of a temperature-changing material, and the temperature-changing material causes the phase change layer 21 to undergo a phase change after the temperature reaches a predetermined temperature, so that the wall material of the temperature-changing microcapsule ruptures and releases the first substance. In the present application, when the above-mentioned phase change layer 21 is applied to a temperature-changing indicator, when the external temperature of the temperature-changing indicator reaches a predetermined temperature, the temperature-changing material in the phase change layer 21 undergoes a phase change, the wall material ruptures, and the phase change layer 21 becomes transparent. This transparent state can be permanently presented after it occurs, and the wall material rupture reaction of the temperature-changing microcapsule is very rapid after reaching the predetermined temperature, thereby shortening the time it takes for the functional layer 2 to become transparent after reaching the predetermined temperature. Compared with the existing technology, the TG value (temperature resistance value) of the temperature-variable microcapsule wall material can be precisely controlled. By preparing temperature-variable microcapsules with different TG values, irreversible temperature-variable indicators with precise different predetermined temperatures can be prepared. Ultimately, the irreversible temperature-variable indicator can accurately monitor the external environment in which the equipment is located. The above-mentioned irreversible temperature-variable indicator is very suitable for temperature monitoring under high-voltage conditions such as precision instruments with strict temperature requirements and power cables.

[0028] As a further preferred embodiment, the temperature-variable material is one or more of polymethyl methacrylate, polyisocyanate, polyurea, and polyamide. The present application adjusts the TG value of the temperature-variable microcapsule wall material by preparing wall materials of different materials, thereby adjusting the indicated temperature of the irreversible temperature-variable indicator. The indicated temperature of the irreversible temperature-variable indicator can be 30°C to 200°C, such as: 37°C, 45°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, etc.

[0029] In a preferred embodiment, the first substance is silicone oil. Preferably, the ratio of silicone oil to temperature-change material is 5:1, calculated by mass percentage. The absorbent layer 22 is paper. When the functional layer 2 comprises temperature-change microcapsules whose core material is silicone oil, the walls of the temperature-change microcapsules rupture upon reaching a predetermined temperature, allowing the silicone oil to leak out and soak into the paper. The paper and phase change layer 21 become transparent, revealing the underlying base color layer 13, thus achieving an irreversible color development effect. The absorption of silicone oil by the paper allows it to quickly become transparent, shortening the time it takes for the functional layer 2 to become transparent after reaching the predetermined temperature.

[0030] As a preferred embodiment, a protective layer 3 is further provided on the side of the functional layer 2 away from the base layer 1. The protective layer 3 is used to protect the adsorption layer or the phase change layer 21 from being damaged.

[0031] In the present application, the base layer 1 includes a release layer 11, an adhesive layer 12, and a base layer 13 stacked in sequence. The base layer 13 is disposed below the functional layer 2 so that the functional layer 2 becomes transparent and displays color after reaching a predetermined temperature. The adhesive layer 12 is disposed below the base layer 13 so that the irreversible temperature change indicator can be attached to the object to be measured. The release layer 11 is detachably disposed below the adhesive layer 12. When the irreversible temperature change indicator using the base layer 1 is applied to the object to be monitored, the release layer 11 is first removed, and then the adhesive layer 12 is applied to attach the irreversible temperature change indicator to the object to be monitored. The structural design of the base layer 1 is conducive to the storage of the irreversible temperature change indicator and is easy to operate, which is conducive to market promotion.

[0032] As a preferred embodiment, the base layer 13 is prepared from a colored slurry, which facilitates coating or printing, thereby producing a uniform base layer 13. Furthermore, the colored slurry includes an inorganic pigment, which is heat-resistant. When the irreversible temperature indicator is at a higher temperature, the base layer 13 is not damaged by excessive temperature. Preferably, the inorganic pigment is any one or more of chrome yellow, iron blue, cadmium red, cadmium yellow, lithopone, carbon black, red iron oxide, and yellow iron oxide.

[0033] As a preferred embodiment, the adhesive layer 12 is double-sided tape. The structure of the double-sided tape facilitates adhesion between the release layer 11 and the base layer 13, or facilitates the preparation of the base layer 13. The double-sided tape is prepared from a single component, which is simple to operate; only the corresponding adhesive needs to be coated into a film. The single component can be, but is not limited to, any one of white oil glue, yellow hot melt glue, water glue, and embroidery glue. The double-sided tape can also be prepared from multiple components, mixing glues of different viscosities to produce adhesives of different viscosities, thereby increasing the selectivity of the double-sided tape. The multiple components can be, but are not limited to, at least two of the following: white oil glue, yellow hot melt glue, water glue, and embroidery glue.

[0034] In a preferred embodiment, the additive comprises a water-based resin and also includes at least one of a dispersant, a leveling agent, a defoamer, and a thickener. A dispersant is a surfactant with opposing lipophilic and hydrophilic properties within its molecule. Its primary function is to uniformly disperse solid and liquid particles of inorganic and organic pigments that are difficult to dissolve in liquids. It also prevents particle sedimentation and aggregation, creating an amphiphilic agent necessary for a stable suspension. A leveling agent primarily improves the leveling properties of the ink during printing, forming a smooth, even film during the drying process. It effectively reduces the surface tension of the ink, improving its leveling and uniformity. A defoamer primarily reduces the surface tension of water, solutions, suspensions, etc., preventing foam formation or reducing or eliminating existing foam, ultimately acting as a defoamer during printing. A thickener acts as a surfactant, adsorbing onto the surface of the dispersed phase, imparting a certain degree of hydrophilicity and facilitating dispersion in aqueous systems. The molecular weight distribution, concentration, solution temperature, pH, and shear rate of the thickener all affect the viscosity of the solution. The present application is to prepare temperature-variable slurries with different properties by regulating the thickener.

[0035] The present application also provides a method for preparing an irreversible temperature change indicator. The irreversible temperature change indicator includes a base layer 1 and a functional layer 2. The irreversible temperature change indicator is prepared by the following method: the functional layer 2 is stacked on the base layer 1, and the functional layer 2 becomes transparent after the temperature reaches a predetermined temperature, so as to display the color of the base layer 1.

[0036] As a preferred embodiment, the base layer 1 includes a release layer 11, an adhesive layer 12 and a base color layer 13. The base layer 1 is prepared by the following method: uniformly spraying adhesive material on any surface of the release layer 11 to achieve stacking the adhesive layer 12 on the release layer 11; uniformly spraying colored slurry on the surface of the adhesive layer 12 away from the release layer 11 to achieve stacking the base color layer 13 on the adhesive layer 12.

[0037] As a preferred embodiment, the functional layer 2 is stacked on the base color layer 13, and the functional layer 2 includes a phase change layer 21. The phase change layer 21 is prepared by the following method: S1, preparing a temperature-changing slurry; S2, uniformly coating the temperature-changing slurry into a film and then curing it to form the phase change layer 21.

[0038] As a preferred embodiment, the functional layer 2 further includes an absorption layer 22, and the absorption layer 22 is prepared by the following method: when the absorption layer 22 only includes a first absorption layer 22 located between the base color layer 13 and the phase change layer 21: first prepare the first absorption layer 22 on the base color layer 13, and then uniformly apply the temperature-changing slurry on the first absorption layer 22 and solidify it to form the phase change layer 21; or; when the absorption layer 22 only includes a second absorption layer 22 located on the surface of the phase change layer 21 away from the base color layer 13: directly The second absorption layer 22 is prepared on the surface of the phase change layer 21 away from the base color layer 13; or; when the absorption layer 22 includes a first adsorption layer located between the base color layer 13 and the phase change layer 21 and a second adsorption layer located on the surface of the phase change layer 21 away from the base color layer 13: the first absorption layer 22 is first prepared on the base color layer 13, and then the temperature-changing slurry is uniformly coated on the first absorption layer 22 and then cured to form the phase change layer 21, and the second absorption layer 22 is prepared on the surface of the phase change layer 21 away from the base color layer 13.

[0039] Regarding the preparation method of this application, this application also provides the following examples to demonstrate that the method of this application can successfully prepare an irreversible temperature change indicator, and the preparation method is simple. The performance of the prepared irreversible temperature change indicator was also tested.

[0040] Example 1

[0041] In this embodiment, an irreversible temperature change indicator with a predetermined temperature of 80° C. is prepared. When the irreversible temperature change indicator reaches the predetermined temperature of 80° C., the irreversible temperature change indicator turns yellow. The steps for preparing the irreversible temperature change indicator are as follows:

[0042] Polymethyl methacrylate (PMMA) with a TG value of 80°C is selected as the wall material of the temperature-changing microcapsule, and silicone oil is selected as the core material of the temperature-changing microcapsule. The ratio of silicone oil to PMMA is 5:1 in terms of mass percentage to prepare the temperature-changing microcapsule. The temperature-changing microcapsule is fully stirred with an aqueous resin, a dispersant and a leveling agent to prepare a temperature-changing slurry for standby use. A release film is taken as a release layer, and white oil glue is evenly sprayed on the release layer. After drying, a white oil glue layer (adhesive layer) is formed on the release layer. Then, a chrome yellow-containing slurry is evenly printed on the surface of the white oil glue layer away from the release layer. After drying, a chrome yellow-containing base color layer (base color layer) is formed on the white oil glue layer. The previously prepared temperature-changing slurry is printed on the chrome yellow-containing base color layer and dried at 50°C to form a phase change layer. A paper (absorbing layer) is adhered to the surface of the phase change layer away from the chrome yellow-containing base layer and covers the phase change layer. Finally, a protective film (protective layer) is attached to the surface of the paper away from the phase change layer. After attachment, the preparation of the irreversible temperature change indicator is completed.

[0043] Performance testing: The release film on the back of the irreversible temperature change indicator prepared above, with a predetermined temperature of 80°C, was removed and placed on a heating platform. The temperature was then raised to 90°C. While the temperature remained below 80°C, the indicator remained white. However, after reaching 80°C, it instantly turned yellow, with a response time of 5 seconds. This demonstrates that the irreversible temperature change indicator prepared in this example is of acceptable quality and can rapidly indicate temperature changes through a color change when the ambient temperature reaches the predetermined temperature.

[0044] Example 2

[0045] This embodiment prepares an irreversible temperature change indicator with a predetermined temperature of 37°C. When the irreversible temperature change indicator reaches the predetermined temperature of 37°C, the irreversible temperature change indicator turns red. The steps for preparing the irreversible temperature change indicator are as follows:

[0046] Polymethyl methacrylate (PMMA) with a TG value of 37°C is selected as the wall material of the temperature-changing microcapsule, and silicone oil is selected as the core material of the temperature-changing microcapsule. The ratio of silicone oil to PMMA is 5:1 in terms of mass percentage to prepare the temperature-changing microcapsule. The temperature-changing microcapsule is fully stirred with the water-based resin, dispersant and leveling agent to prepare a temperature-changing slurry for standby use. A release film is taken as the release layer, and a water glue is evenly sprayed on the release layer. After drying, a water glue layer (adhesive layer) is formed on the release layer. Then, a slurry containing red iron oxide is evenly printed on the surface of the water glue layer away from the release layer. After it dries, a base color layer (base color layer) containing red iron oxide is formed on the water glue layer. The previously prepared temperature-changing slurry is printed on the base color layer containing red iron oxide and dried at 50°C to form a phase change layer. A paper (absorbing layer) is adhered to the surface of the phase change layer away from the base color layer containing red iron oxide and covers the phase change layer. Finally, a protective film (protective layer) is attached to the surface of the paper away from the phase change layer. After attachment, the preparation of the irreversible temperature change indicator is completed.

[0047] Performance testing: The release film on the back of the irreversible temperature change indicator prepared above, with a predetermined temperature of 37°C, was removed and the device was placed on a heating platform. The temperature was then raised to 40°C. While the temperature remained below 37°C, the indicator remained white. However, upon reaching 37°C, it instantly turned red, with a response time of 3 seconds. This demonstrates that the irreversible temperature change indicator prepared in this example is of acceptable quality and can rapidly indicate temperature changes through a color change when the ambient temperature reaches the predetermined temperature.

[0048] Example 3

[0049] In this embodiment, an irreversible temperature change indicator with a predetermined temperature of 120° C. is prepared. When the irreversible temperature change indicator reaches the predetermined temperature of 120° C., the irreversible temperature change indicator turns blue. The steps for preparing the irreversible temperature change indicator are as follows:

[0050] Polymethyl methacrylate (PMMA) with a TG value of 120°C is selected as the wall material of the temperature-changing microcapsule, and silicone oil is selected as the core material of the temperature-changing microcapsule. The ratio of silicone oil to PMMA is 5:1 in terms of mass percentage to prepare the temperature-changing microcapsule. The temperature-changing microcapsule is fully stirred with the water-based resin, dispersant and leveling agent to prepare a temperature-changing slurry for standby use. A release film is taken as the release layer, and white oil glue is evenly sprayed on the release layer. After drying, a white oil glue layer (adhesive layer) is formed on the release layer. Then, a slurry containing iron blue is evenly printed on the surface of the white oil glue layer away from the release layer. After it is dried, a base color layer containing iron blue (base color layer) is formed on the white oil glue layer. The previously prepared temperature-changing slurry is printed on the base color layer containing iron blue and dried at 50°C to form a phase change layer. A paper (absorbing layer) is adhered to the surface of the phase change layer away from the base color layer containing red iron oxide and covers the phase change layer. Finally, a protective film (protective layer) is attached to the surface of the paper away from the phase change layer. After attachment, the preparation of the irreversible temperature change indicator is completed.

[0051] Performance test: The release film on the back of the irreversible temperature change indicator with a predetermined temperature of 120°C prepared above was torn off, and the indicator was attached to a heating table. The temperature was raised to 125°C. When the temperature was below 120°C, the irreversible temperature change indicator continued to be white. When the temperature was raised to 120°C, the irreversible temperature change indicator instantly turned blue. The reaction time was 4 seconds. This shows that the irreversible temperature change indicator prepared in this embodiment is of qualified product quality. After the external temperature reaches the predetermined temperature, it can quickly indicate the external temperature change through color change. The irreversible temperature change indicator of this embodiment can be used for high-temperature monitoring of wires and cables.

[0052] In summary, the present application provides an irreversible temperature change indicator, and its color display principle is: when the irreversible temperature change indicator is applied to the equipment to be monitored, before the temperature reaches the predetermined temperature, the color of the base layer cannot be seen due to the translucency of the functional layer. When the temperature reaches the predetermined temperature, the functional layer becomes transparent, thereby allowing the color of the base layer to appear. The sticker can be widely used in monitoring local high temperature or short-circuit overheating of various precision instruments and high-voltage equipment such as power cables. When the irreversible temperature indicator is applied to precision instruments, power cables and other equipment, if local high temperature or short-circuit overheating occurs, the irreversible temperature indicator will display color locally accordingly, which not only reduces the complexity of the entire search process, but also reduces the personnel safety issues for high-voltage equipment during the investigation process. In addition, the irreversible temperature change indicator provided by the present application is simple to operate and has a broad application market.

[0053] Although this specification is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0054] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. An irreversible temperature change indicator, characterized in that: It comprises a base layer and a functional layer stacked together, wherein the functional layer becomes irreversibly transparent when the temperature reaches a predetermined temperature, and is used to display the color of the base layer; The functional layer includes a phase change layer and an absorption layer that are stacked, and the absorption layer is arranged on at least one surface of the phase change layer; The phase change layer undergoes a phase change to present a transparent state after the temperature reaches a predetermined temperature, and releases the first substance; The absorption layer is used to absorb the first substance released after the phase change layer changes, and presents a transparent state; The phase change layer is formed by solidifying a temperature-changing slurry, which includes temperature-changing microcapsules and additives. The temperature-changing microcapsules include a first substance and a wall material that seals the first substance. The wall material is made of a temperature-changing material. The temperature-changing material causes the phase change layer to undergo a phase change after the temperature reaches a predetermined temperature, so that the wall material of the temperature-changing microcapsule ruptures and releases the first substance.

2. The irreversible temperature change indicator according to claim 1, characterized in that: The temperature-variable material is one or more of polymethyl methacrylate, polyisocyanate, polyurea, and polyamide.

3. The irreversible temperature change indicator according to claim 1, characterized in that: The first substance is silicone oil; and the absorption layer is paper.

4. The irreversible temperature change indicator according to claim 1, characterized in that: A protective layer is further provided on the side of the functional layer away from the base layer.

5. The irreversible temperature change indicator according to claim 1, characterized in that: The base layer includes a release layer, an adhesive layer and a base color layer stacked in sequence. The base color layer is arranged below the functional layer so that the functional layer becomes transparent and displays color after the temperature reaches a predetermined temperature; The adhesive layer is provided below the base color layer so that the irreversible temperature change indicator is attached to the object to be tested; The release layer is detachably disposed below the adhesive layer.

6. The irreversible temperature change indicator according to claim 5, characterized in that: The base color layer is prepared from a colored slurry, and the colored slurry includes an inorganic pigment. The inorganic pigment is any one or more of chrome yellow, iron blue, cadmium red, cadmium yellow, lithopone, carbon black, iron oxide red, and iron oxide yellow.

7. The irreversible temperature change indicator according to claim 5, characterized in that: The adhesive layer is a double-sided tape, which is prepared from a single component or multiple components. The single component is any one of white oil glue, yellow hot melt glue, water glue, and embroidery glue, and the multiple components are at least two of the white oil glue, yellow hot melt glue, water glue, and embroidery glue.

8. The irreversible temperature change indicator according to claim 1, characterized in that: The auxiliary agent includes a water-based resin, and the auxiliary agent also includes at least one of a dispersant, a leveling agent, a defoaming agent, and a thickener.

9. A method for preparing an irreversible temperature change indicator, characterized in that: The irreversible temperature change indicator comprises a base layer and a functional layer, and the irreversible temperature change indicator is prepared by the following method: The functional layer is stacked on the base layer, wherein the base layer includes a release layer, an adhesive layer, and a base color layer, and the functional layer becomes transparent when the temperature reaches a predetermined temperature so as to display the color of the base layer; the functional layer is stacked on the base color layer, wherein the functional layer includes a phase change layer and an absorption layer stacked, and the absorption layer is disposed on at least one surface of the phase change layer; The phase change layer undergoes a phase change to present a transparent state after the temperature reaches a predetermined temperature, and releases the first substance; The absorption layer is used to absorb the first substance released after the phase change layer changes phase and presents a transparent state. The phase change layer is prepared by the following method: S1. Preparing a temperature-changing slurry, wherein the temperature-changing slurry includes temperature-changing microcapsules and an additive. The temperature-changing microcapsules include a first substance and a wall material that seals the first substance. The wall material is made of a temperature-changing material. The temperature-changing material causes the phase change layer to undergo a phase change when the temperature reaches a predetermined temperature, thereby rupturing the wall material of the temperature-changing microcapsules and releasing the first substance. S2. The temperature-change slurry is evenly coated to form a film and then solidified to form a phase change layer.

10. The method for preparing an irreversible temperature change indicator according to claim 9, characterized in that: The base layer is prepared by the following method: Evenly spraying adhesive material on any surface of the release layer to stack an adhesive layer on the release layer; The colored slurry is evenly sprayed on the surface of the adhesive layer away from the release layer, so that a base color layer is stacked on the adhesive layer.

11. The method for preparing an irreversible temperature change indicator according to claim 9, characterized in that: The absorption layer is prepared by the following method: When the absorption layer only includes a first absorption layer located between the base color layer and the phase change layer: firstly prepare the first absorption layer on the base color layer, then uniformly coat the temperature change slurry on the first absorption layer and then solidify it to form the phase change layer; or; When the absorption layer only includes a second absorption layer located on the surface of the phase change layer away from the base color layer: directly preparing the second absorption layer on the surface of the phase change layer away from the base color layer; or; When the absorption layer includes a first absorption layer located between the base color layer and the phase change layer and a second absorption layer located on the surface of the phase change layer away from the base color layer: first prepare the first absorption layer on the base color layer, then uniformly coat the temperature-changing slurry on the first absorption layer and solidify it to form a phase change layer, and prepare the second absorption layer on the surface of the phase change layer away from the base color layer.

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