Multi-temperature irreversible thermal indicator

Abstract

The invention relates to the field of thermal indicating devices in the form of multi-temperature irreversible thermal indicators having a thermal indication scale that includes small thermal sensitive elements and an additional large thermal sensitive element. The present irreversible thermal indicator comprises a base having disposed thereon thermal sensitive elements that are capable of irreversibly changing their external appearance when respective corresponding threshold temperatures are reached, said thermal sensitive elements including at least two small thermal sensitive elements (STE1 and STE2) having different activation temperatures and at least one large thermal sensitive element (LTE). The area of the LTE is at least twice as large as the area both of STE1 and of STE2. The invention provides for the increased operational safety of equipment provided with thermal indicators according to the invention by allowing easy interpretation of the thermal indicator monitoring results without decreasing the informational value thereof.

Description

[0001] Multi-temperature irreversible temperature indicator with a temperature indicator scale and an additional large temperature-sensitive element

[0002] Field of technology to which the invention relates

[0003] The invention relates to the field of temperature-indicating devices, which are multi-temperature irreversible temperature indicators, designed to detect the fact of heating of a controlled element above several specified threshold temperatures, containing: several small temperature-sensitive elements (STE) forming a temperature-indicating scale,

[0004] - at least one large temperature indicator element (LTE) that stands out among the MTEs due to its size.

[0005] State of the art

[0006] An increase in temperature is one of the first and most common signs of developing defects in various equipment, such as increased contact resistance in power generation, interturn short circuits in electric motor windings, charger or battery failure in household appliances, and bearing malfunctions in mechanical equipment. Early detection of such overheating allows for troubleshooting and the prevention of equipment failure, shutdowns, or fires. Technical and regulatory documents establish maximum permissible temperatures, heating above which should be considered a defect requiring the equipment to be taken out for repair (for example, RD 34.45-51.300-97, RD 153-34.0-20.363-99, GOST 8865-93, 8024-90, 10693-81, 2213-79, 10434-82, 16708-84, 2585-81, 32397-2020, 26346-84, 839-2019, GOST R 51321.1-2007, etc.).

[0007] Among the known methods of temperature monitoring, temperature-indicating monitoring has become widely used. This method relies on temperature indicators that visually detect the occurrence and / or past occurrence of heating above a threshold temperature. The threshold temperature is set during manufacturing of the temperature indicator and is determined by the nature (structure) of the material from which the temperature-sensitive element (TE) is made. Temperature indicators can be varnishes and paints, or devices containing temperature-sensitive components (e.g., stickers, clips, tips, etc.).

[0008] The advantages of using temperature-indicating devices over thermal paints and varnishes include the absence of direct contact between the surface of the test object and the temperature-sensitive component, the ability to use multiple components with different threshold temperatures in a single device, and the ability to display additional information on the device (e.g., response temperature, expiration date, markings, etc.). Furthermore, the accuracy of heat detection on temperature-indicating devices is higher than that of varnishes and paints, since the temperature-sensitive component is applied in the factory.

[0009] Thermal indicators can be reversible, that is, changing their appearance only when heated and returning to their original color upon cooling, or irreversible, changing their appearance after exceeding a given temperature and maintaining their changed appearance after cooling.

[0010] A special feature of reversible temperature indicators is that they only provide information about current overheating, that is, about exceeding the temperature threshold at the time of inspection.

[0011] Irreversible temperature indicators allow one to detect the fact that the threshold temperature has been exceeded during the entire period of operation, regardless of the heating temperature value at the time of inspection.

[0012] Irreversible temperature indicators are available in single-temperature and multi-temperature versions. Single-temperature indicators detect the exceeding of a single threshold temperature. This temperature could, for example, be the maximum permissible temperature of the monitored element. Single-temperature indicators are extremely easy to operate and interpret thermal monitoring results, but they only alert personnel to the occurrence of overheating above the set temperature. When using single-temperature indicators, after detecting a trip, additional thermal imaging or other investigation is necessary to determine the cause of the trip, the extent of the defect, etc.

[0013] Depending on the type of surface being monitored and the purpose of temperature monitoring, single-temperature temperature indicators can be selected to record: equipment commissioning; defect occurrence; defect development; emergency heating; fire-hazardous heating, etc. However, in each of these cases, a single-temperature temperature indicator can only solve one of the tasks. It is impossible to track the heating (defect) dynamics before and after the single-temperature temperature indicator is triggered and assess the condition of the object.

[0014] For example, in the case of monitoring the initial commissioning, a single-temperature thermal indicator will only provide an answer to the question about the fact of commissioning, but will not record the occurrence of a defect.

[0015] In the case of monitoring the maximum permissible temperature with a single-temperature thermal indicator, the activation of the thermal indicator indicates an emergency defect, but does not allow the detection of the early stages of the defect, or the determination of the extent to which the defect that has arisen is dangerous for continued operation.

[0016] Therefore, for a more in-depth analysis of the monitored component's condition, it is necessary to use irreversible multi-temperature temperature indicators. Irreversible multi-temperature temperature indicators feature a temperature indicator scale consisting of several thermoelements whose appearance irreversibly changes at different temperatures. The temperature indicator scale allows for the maximum temperature reached by the monitored component during operation to be determined with a given accuracy. This allows for the tracking of defect development dynamics over time, the ability to compare the maximum heating temperatures of identical equipment components (assemblies), and the determination of excess temperature, defect rate, and defect development stage. Examples of such temperature indicators include multi-temperature temperature indicator stickers (TIS), in which the thermoelements are applied to form a temperature indicator scale similar to a thermometer. These include irreversible temperature indicators such as "Testoterm," "Thermindex," "Brady," and "L-Mark."Also known are multi-temperature melting temperature indicators, in which TEs with different temperatures alternate (RU 2801907 C1, published 08 / 18 / 2023).

[0017] However, the use of the described multi-temperature temperature indicators complicates the defect detection process due to the need to analyze the results of their activation. Ultimately, this leads to increased processing time, errors in interpreting the activated temperature indicators, and the need for specialized training for specialists inspecting such temperature indicators.

[0018] To simplify the analysis of the results of the operation of multi-temperature thermal indicators, the following logic is often used: the absence of the operation of the TE indicates the absence of a defect; partial operation of the TE indicates the development of a defect; the operation of all TE indicates an emergency defect (Lvov M.Yu., Lesiv A.V. Thermal indicator monitoring of contacts and contact connections of electrical equipment and power transmission lines. Moscow: NTF "Energoprogress", "Energetik", 2023. p. 62; Lvov M.Yu., Nikitina S.D., Lvov Yu.N., Lesiv A.V. On the standardization of requirements for thermal indicator monitoring of the state of contacts and contact connections during the operation of electrical installations / / Energy of the unified network. 2023. No. 1 (68). pp. 67-74).However, this approach has a number of disadvantages: when using it, it is impossible to determine how much the equipment heated up after reaching the highest permissible (emergency) temperature, whether the equipment poses a danger to personnel at the time of inspection, what was the cause of the defect, the extent of repairs required, etc. (Fig. 2).

[0019] Another approach to simplifying the interpretation of the results of the operation of multi-temperature thermal indicators is the use of thermal indicators with different color transitions.

[0020] An example of the implementation of such an approach is the reversible temperature indicator “Traffic Light”, which has one TE, which, depending on the temperature, changes color from green to yellow and, with a further increase in temperature, to red, and upon cooling, the reverse color transition occurs.

[0021] (https: / / markerpro.ru / product / termoindikator-dlya-goryachih-poverhnostej-svetofor-hallcrest-traffic-light / ). A feature of this solution, which limits its use, particularly in the electric power industry, is its reversible operation, which prevents detection of overheating throughout the entire period of operation, but only provides information about heating at the moment of heating.

[0022] There are known temperature indicator stickers containing three TEs, which, when triggered, reveal the color of the base under the corresponding material, with the base under each material being painted in its own color (green, yellow, red or red, blue, burgundy) (https: / / www.nichigi.co.jp / en / en_products / temperature_top / durable_en_samo / new3E.html).

[0023] However, using a different color for each TE does not allow us to focus on a specific response temperature.

[0024] It would be interesting to combine the ease of interpreting the response of a single-temperature indicator with the informational value of a multi-temperature indicator in a single temperature indicator. To address this issue, we propose using a temperature indicator containing a temperature indicator scale and an additional, distinct TE scale. The temperature indicator scale allows for analyzing the equipment's condition, the reasons for the indicator's activation, and drawing conclusions about the defect's development dynamics, causes, maximum heating temperature, etc. The additional, distinct TE scale allows for unambiguous notification of a specific equipment condition requiring increased attention and / or special measures (shutdown, indicator scale analysis, additional diagnostics, etc.).

[0025] The present invention proposes a solution to this problem by using TEs of varying sizes. The large temperature-sensitive element (LTE) is most visible during initial inspections and is triggered at a certain temperature threshold, requiring a response from operating personnel. Small temperature-sensitive elements (STEs) form a temperature-indicating scale and allow for more precise heating temperature determination during a more detailed analysis.

[0026] An example of this approach is the thermochemical indicator described in US11821798B2, October 21, 2023, in which, upon activation, a metal substrate is etched, resulting in a color change. Initially, the etchant is separated from the metal substrate by a barrier material of varying thickness and composition and is selected to ensure contact between the passive and active components when a threshold temperature is exceeded for a specified period of time. The indicator has several temperature-sensitive areas, the size of which is proportional to the time of exposure to elevated temperature. The commercial "WarmMark" thermal indicator (http: / / www.warmmark.ru / warmmark / ), designed for rapid temperature monitoring during temporary storage and transportation of heat-sensitive products and selected as a prototype, is similarly constructed.The front panel of this temperature indicator has three windows—small, medium, and large—that sequentially turn red when the trigger temperature exceeds the activation temperature by 2 degrees. If the temperature returns to normal, the coloring is suspended. The temperature indicator operates based on the thermochemical reaction of an internal dye when the temperature rises above the manufacturer's set values. This allows one to determine the approximate time of exposure to high temperatures. The activation of the small window indicates a short-term temperature violation (from 0.5 to 2 hours), while the activation of the large window indicates a prolonged temperature excess (from 8 to 48 hours). The threshold temperatures for all three windows are the same, and the long response time does not allow this temperature indicator to be used in equipment, as the heating may be short-lived.

[0027] 3M's MonitorMark temperature indicators (https: / / fleetservice.ru / wp-content / uploads / 2020 / 07 / 3m_Cold.pdf) are also well-known for monitoring cold chain temperature conditions. When exposed to a temperature exceeding a predetermined value, the chemical in the tank melts and begins to flow along the belt. The blue coloration first appears at the left edge of the first viewing window and gradually moves from left to right, toward the end of the belt. The speed of the blue coloration depends on the temperature. Any appearance of blue coloration in the first indicator window indicates that the predetermined temperature threshold has been exceeded. The path traveled by the coloration ("recording time") along the indicator windows allows one to estimate the maximum time of exposure to a temperature above the threshold. Moreover, a brief exposure to a relatively high temperature produces a coloration comparable to a longer exposure to a lower temperature.

[0028] However, despite the fact that the solutions described contain heating elements of varying area, such temperature indicators are designed to monitor the duration of exposure to elevated temperatures. The aforementioned temperature indicators are designed to monitor the cold chain temperature regime (the storage temperature regime of frozen products). All heating elements of these indicators have the same response temperature (similar to a single-temperature indicator).

[0029] Thus, there are no known solutions from the state of the art that combine single- and multi-temperature temperature indicators with simple interpretation of results and preservation of the information content of multi-temperature control.

[0030] Thus, there is a need to create an irreversible multi-temperature thermal indicator for detecting the fact of heating of a controlled element above several specified threshold temperatures, containing two or more small TEs that form a thermal indicator scale, and one large TE that stands out among the small TEs due to its size.

[0031] Terms, definitions and abbreviations used in describing the present invention

[0032] The following terms, definitions and abbreviations used in describing the present invention are intended for a better and more precise understanding of the present invention, but do not limit the present invention to the stated wording.

[0033] The term "thermal indicator" refers to a device that changes its appearance (specifically, color) when heated above one or more threshold temperatures. Typically, a thermal indicator consists of a base, designed to secure the thermal indicator to the monitored surface, and one or more temperature-sensitive elements (TEs) located on the front side of the base, which change their appearance when heated.

[0034] Single-temperature temperature indicators include temperature indicators that have one or several temperature elements that are triggered when one threshold temperature is reached.

[0035] Multi-temperature temperature indicators include temperature indicators that have several heating elements that differ in their response temperature (threshold temperature).

[0036] The term "irreversible" defines thermal indicators that, after heating to the operating temperature, visually change their appearance, in particular their color, in such a way that after cooling below the operating temperature, their appearance does not return to a form that is visually indistinguishable from the original.

[0037] The term "temperature-sensitive element (TSE)" refers to a temperature indicator element that changes its appearance when a threshold temperature is reached. The TSE may contain one or more substances. Upon reaching the threshold temperature, the TSE may change color or transparency. In the latter case, the visual effect of the temperature indicator's activation is determined by the color of the base located beneath the TSE. The change in color or transparency of the TSE upon reaching the threshold temperature may occur due to a chemical reaction, the melting of one or more substances, other phase transitions, or more complex processes. The TSE may also additionally include solid or gaseous inclusions located within the volume of the temperature-sensitive component; support elements; and an absorbent material onto which the temperature-sensitive component is applied.

[0038] The present invention prefers to use FCs whose operation is based on a change in appearance upon melting, in particular a change in transparency. However, the invention is not limited to the use of only such components, and FCs may be constructed using components operating on a different principle. The terms "small temperature-sensitive element (STE)" and "large temperature-sensitive element (LTE)" are relative and are defined by the area of ​​the FC. For the purposes of the present invention, the area of ​​the LTE is at least twice the area of ​​the STE. STEs preferably have comparable areas and differ by no more than 20%. Each STE may utilize temperature-sensitive components operating on a predominantly identical principle. STEs and LTEs may utilize FCs based on different operating principles if required to ensure the required technical characteristics.The initial color and color transition of MFCs and BFCs are generally the same, but may differ depending on the purpose of the temperature indicator. MFCs are typically arranged on the temperature indicator so as to form a temperature indicator scale.

[0039] “Thermal indicator scale” includes a set of two or more TE (TE i, TE2 .... TE П ), having different threshold temperatures (operation temperatures) - Ti, T2 .... T п respectively), located on the temperature indicator sequentially in order of increasing response temperature.

[0040] Threshold temperature is the minimum value of the heating temperature of a thermal indicator during the time required to achieve an equilibrium (unchanging over time) state, at which the appearance of the TE of a given thermal indicator changes.

[0041] The "color transition of a temperature-sensitive element" refers to the change in color of the temperature indicator upon activation of the TE. When describing the color transition, the color before activation is first indicated, followed by the color after activation. For example, a TE that is initially white (opaque) and after activation becomes transparent, revealing the color of the black base underneath, is said to have a white-to-black color transition. In some cases, either the TE or the base underneath may bear inscriptions indicating, for example, the numerical value of the TE's threshold temperature, or signal symbols. In this case, the color of the TE before or after activation refers to the color of the background on which such inscriptions or symbols are applied, or the color transition of the main surface of the TE.

[0042] A change in the appearance of a temperature indicator or TE that occurs solely as a result of heating to any of the possible temperature thresholds is called "activation." In the context of the present invention, activation of a temperature indicator is preferably associated with an increase in transparency achieved by melting a substance or group of substances comprising the TE.

[0043] A change in the appearance of a temperature indicator, in particular the color and / or transparency of the TE, that occurs as a result of an external influence other than heating the temperature indicator above the corresponding temperature threshold values, is called a “false triggering of the temperature indicator.”

[0044] A "Thermal Indicator Sticker (TIS)" is a device that acts as a temperature indicator and can be adhered to a test object using an adhesive layer applied to the back of the base during the manufacturing process. The TIS comprises a flexible elastic base, the back of which is coated with an adhesive layer protected by a release agent prior to installation on the test object, and the front of which contains areas with a thermal element, which, in turn, can be coated with a protective layer.

[0045] The term "visible light" defines a narrow region in the electromagnetic spectrum in the frequency range of 3.8 - 10 14 - 7.9 - 10 14 Hz, which corresponds to wavelengths in a vacuum from ~400 to ~760 nm, which can be distinguished by the human eye.

[0046] The term "opaque to at least part of the visible light spectrum" means a material that does not transmit all or part of the visible light spectrum.

[0047] The term "transparent to at least part of the visible light" means a material that allows all or part of the visible light spectrum to pass through.

[0048] "Response speed" is the maximum time required for a temperature indicator or TE to transition from its initial state to its activated state after the TE has heated to the response temperature, taking into account the specified accuracy of registering when the threshold temperature is exceeded. For the purposes of the present invention, the response speed of a temperature indicator is no more than 5 seconds, preferably no more than 2 seconds.

[0049] For the purposes of the claimed invention, the term “threshold temperature” means the temperature value at which a change in the external appearance of the TE occurs (its operation), determined with a given accuracy.

[0050] The term “accuracy of recording the excess of the threshold temperature” refers to the boundaries of the range of temperature values ​​that meet the following conditions (1) - (3):

[0051] (1) until the threshold temperature is reached minus the specified accuracy value, the corresponding TE does not change its appearance (in particular, it remains opaque to at least part of the visible light), and the temperature indicator in this area does not change its appearance;

[0052] (2) when the threshold temperature is exceeded, taking into account the specified accuracy, the corresponding TE is triggered, in particular, with an increase in transparency achieved by melting one substance or a group of substances included in the TE, and the thermal indicators in this area acquire an appearance different from the original;

[0053] (3) in the case of using a FC in which the change in appearance upon reaching a threshold temperature is associated with an increase in transparency achieved by melting one substance or a group of substances included in the FC, the exact value of the melting phase transition temperature of the substance is within a specified range and is not further determined. The accuracy of recording the excess of the threshold temperature determined by the present invention is preferably no more than 5 °C, most preferably no more than 2 °C.

[0054] The term "gas-filled hot-melt material" (GFTM) defines a material comprising a solid phase or phases, as well as a gas phase contained within the cavities of the solid phase. At least one of the GFTM solid phases, referred to as the "hot-melt phase," is capable of melting when heated to a threshold temperature. The gas phase is predominantly distributed uniformly throughout the GFTM, with most of the pores interconnected, allowing for the unimpeded distribution and release of gas during heating and / or melting of the material. The gas pressure within the pores may be less than atmospheric pressure, equal to atmospheric pressure, or greater than atmospheric pressure.

[0055] The solid phase of the thermal-sintering material may additionally include particles of a solid substance with a melting point above the threshold, the strength of which predominantly exceeds that of the thermal-sintering phase, polymers that completely or partially coat the thermal-sintering phase, and other inclusions. Such substances or inclusions are used to increase the mechanical strength of the thermal-sintering material.

[0056] The hot-melt phase contains the "active (main) substance of the HTPM"—a substance, specifically an organic compound, that determines the melting point of the HTPM (the threshold temperature for the FC to operate). The mass content of the active substance in the HTPM structure generally exceeds the content of other HTPM components. The term also refers to a mixture of such substances.

[0057] The term "organic substances" restricts the class of chemical substances that contain carbon atoms bonded to atoms of other chemical elements, excluding metal carbides, metal and ammonium carbonates, and carbon oxides.

[0058] The term "gas phase" by default refers to the gas-filled pores within the gas-filled thermocouple. The gas phase can be air, nitrogen, inert gases, or other substances in the gaseous state under the operating conditions of the thermocouple.

[0059] The term "gas phase fraction in a gas-filled slurry mixture" refers to the ratio of the pore volume within the gas-filled slurry mixture to the total volume of the gas-filled slurry mixture, or the ratio of the area of ​​gas-filled regions to the total area of ​​a section of the gas-filled slurry mixture in one of its cross-sections. For purposes of the present invention, the gas phase fraction can be determined using one of the following methods.

[0060] The first method involves scanning electron microscopy of the surface of a section of the gas-filled slurry using software that calculates the total external surface area of ​​the sample's solid particles and their agglomerates in the section. The area of ​​gas-filled regions is calculated by subtracting the total surface area of ​​the solid particles and their agglomerates from the area of ​​the analyzed region. To determine the proportion of the gas phase, the resulting value for the area of ​​gas-filled regions is divided by the area of ​​the analyzed region. Measurements are performed on 5-7 sections of the gas-filled slurry, and the average value is calculated.

[0061] The second method is based on X-ray microtomography. Sample preparation is similar to the first method. A section of the gas-phase material of known volume is analyzed using a laboratory digital X-ray tomograph with software capable of calculating the percentage of gas in a given sample volume. Measurements are taken from 5-7 sections of the material, obtaining an average value for the gas phase content, expressed as a percentage.

[0062] Any method for determining the gas phase fraction can be applied to finished products containing gas-phase materials, such as temperature indicators. During sample preparation, a uniform section of the product is cut out and the protective layer is removed to ensure the integrity of the gas-phase material.

[0063] In the context of describing a thermal melting system, a "phase" refers to the homogeneous portion of the thermal melting system, separated from the other portions by a visible interface where some phase characteristics, such as density, composition, or optical properties, abruptly change. The collection of individual homogeneous parts of the system, each possessing identical properties, is considered a single phase. The thermal melting system may also contain solid particles with a melting point above the threshold, whose strength predominantly exceeds that of the thermal melting phase, as well as other inclusions.

[0064] The term "GTPM structure" defines the spatial arrangement of solid particles and gas-filled pores in a GTPM sample. The GTPM structure determines its physical, optical, and mechanical properties. Upon reaching a threshold temperature, melting of at least one of the solid phases of the GTPM occurs. During the melting process, the GTPM structure changes, that is, the spatial arrangement of particles and / or volumes of individual phases of the material, their size, and shape. Destruction of the structure may include the following stages: melting of the GTPM particle surface, their compaction, reduction of the pore size within the GTPM and the gas-solid interface area, and particle fusion up to their complete fusion and the formation of a monolithic layer (melt) or a single phase. The process of GTPM structure destruction is accompanied by an irreversible decrease in the volume fraction of the gas phase within the GTPM. The proportion of the gas phase in the material obtained after the activation of the temperature indicator is less than in the initial state of the GTPM.

[0065] When describing a thermoplastic composite with a thermal-melting phase, the term "binder" refers to a material or substance, preferably a high-molecular-weight organic compound, that enables the adhesion of solid particles relative to one another. A solid thermal-melting phase binder, in particular, increases the strength of the thermal-melting phase and reduces its abrasion, and can also ensure the adhesion of the thermal-melting phase to the base or absorbent material.

[0066] By "hermetic protective layer" is meant a protective layer that is impermeable to air and water at atmospheric pressure and in the absence of mechanical impact, made without gaps or holes, and tightly connected to the base by welding or gluing in such a way that the joint is also impermeable to air and water at atmospheric pressure and in the absence of mechanical impact.

[0067] The term "absorbent material" refers to a material capable of receiving and retaining, by any means, a molten, hot-melt material, such as a molten active substance or a hot-melt phase. Retention may occur through wetting, adsorption, absorption, or penetration of the melt into pores or other internal cavities of the absorbent material. A special case of an absorbent material is a "sorbent material." A "porous material," which is a solid material containing free space in the form of cavities, channels, or pores and characterized by a developed surface area, can be used as an absorbent material within the framework of the present invention. The main parameters of porous materials are porosity, pore size, pore size distribution, and specific surface area. For the purposes of the claimed invention, the use of "microporous materials" containing pores with a diameter of less than 2 μm is preferred.

[0068] The term "sorption" should be understood in its most general sense as the absorption of various substances by a solid body. The substance being absorbed is called the "sorbate," and the absorbing solid or liquid is called the "sorbent." For the purposes of the present invention, when describing a fuel cell with a thermal-steel-based material (TSM), the sorbate is the molten TSM, i.e., the liquid, and the sorbent is various solid absorbent materials. "Absorption" is preferred as a special case of sorption, resulting in the absorption of the sorbate by the entire volume of the sorbent, increasing the mass of the sorbent with a slight increase in its volume and changes in its physical properties, particularly its strength.

[0069] The term “support element” or “support element (SE)”, when describing a TE with a GTPM, defines an arbitrary element located in the region of the GTPM, which has a melting temperature greater than the operating temperature of the given GTPM, and which can take on most of the mechanical stress acting on the GTPM in the transverse direction, thereby preventing significant destruction of the GTPM structure.

[0070] The term “defect” indicates the non-compliance of the control object with the requirements established by the documentation, at least for one indicator.

[0071] The "defectivity factor" is the ratio of the measured temperature rise of the contact connection to the temperature rise measured on the entire section of the busbar or wire, located at a distance of at least 1 m from the contact connection.

[0072] The “brightness coefficient” is defined according to GOST 8784-75 as the ratio of the brightness of the coating to the brightness of the standard, measured under the same lighting conditions with a light incidence angle of 45°.

[0073] "Excess temperature" is the excess of the measured temperature of the controlled object over the temperature of similar units of other phases located in the same conditions.

[0074] The term "fire-hazardous heating" refers to the heating of an electrical component to a temperature that poses a risk of ignition of one or more of the components' materials. The term "flexible" refers to materials that have the ability to change shape under external influences so that their functional properties remain unchanged upon returning to their original shape.

[0075] The term "elasticity" refers to the ability of a material or product, when bent around a cylindrical surface, to conform to its shape without losing its functional properties.

[0076] The terms "elastic base" and "elastic protective layer" characterize the base or protective layer material, which is capable of changing its shape without breaking under external influence.

[0077] The essence of the invention

[0078] The objective of the claimed invention is to create an irreversible multi-temperature thermal indicator for diagnosing the thermal state and detecting the fact of heating of the controlled element above several specified threshold temperatures, containing at least two small temperature-sensitive elements that form a temperature-indicating scale, and at least one large temperature-indicating element that stands out among the small temperature-sensitive elements due to its size.

[0079] The technical result of the claimed invention consists in increasing the safety of operation of equipment equipped with temperature indicators according to the invention, by ensuring the simplicity of interpretation of the results of temperature indicator control, without loss of its information content.

[0080] According to the invention, the technical result is achieved by an irreversible temperature indicator, which includes a base on which temperature-sensitive elements (TE) are located, designed with the possibility of an irreversible change in appearance upon reaching their corresponding threshold temperatures, among which at least two small temperature-sensitive elements (STE1 and STE2) can be distinguished, having different threshold temperatures; at least one large temperature-sensitive element (LTE); characterized in that the area of ​​the LTE is at least twice the area of ​​both STE1 and STE2 (Fig. 1).

[0081] The need to use an irreversible temperature indicator is due to the need to detect the heating of the monitored element above the threshold temperature throughout its entire operating period, regardless of the load and temperature of the equipment at the time of inspection. The need to use both a MFC and a BFC in a single temperature indicator is due to the fact that the monitored element can be small (for example, the size of contact connections in electrical panels). In this case, it is physically impossible to install two temperature indicators on the monitored element: one single-temperature and one multi-temperature.

[0082] The temperature indicator scale used in the proposed temperature indicator contains two or more, and preferably three or more, MFCs that operate at different temperatures. Using a temperature indicator scale allows for:

[0083] - determine the fact that the set temperature has been exceeded;

[0084] - compare the values ​​of maximum heating temperatures of identical units;

[0085] - determine the excess temperature or defect coefficient with a given accuracy;

[0086] - determine the dynamics of defect development over time;

[0087] - solve other practical problems depending on the type of equipment used.

[0088] The BTE, which, in certain cases, can be part of a temperature indicator scale, but differs significantly from the MTE in size, is necessary to solve the following problems:

[0089] - simplification of the analysis of the results of the operation of the temperature indicator due to prioritization (focusing the attention of personnel) on a specific temperature;

[0090] - increasing the visibility of a triggered temperature indicator for a critical temperature from a greater distance, including at night or in low-light conditions;

[0091] - localization of a specific defect location on the surface.

[0092] In other words, the activation of the BTE means that it is necessary to pay attention to the MTE scale and take certain measures based on the results of its analysis. Moreover, due to the magnitude of the BTE (at least twice as large as the MTE), its activation is noticeable and clearly visible, minimizing the possibility of error.

[0093] Thus, the combination of operating principles and analysis of the results of single- and multi-temperature temperature indicators ensures increased safety in the operation of equipment equipped with such temperature indicators, due to the information content and ease of interpretation of the results of temperature indicator control.

[0094] The response speed of at least one FC, primarily a BFC, preferably a BFC and a MFC, according to the present invention is no more than 5 seconds and is ensured by the FC's operating principle. This speed is necessary for recording short-term heating events caused by peak (emergency) loads or, for example, short-circuit currents. In particular, this response speed requirement is essential for the use of temperature indicators in monitoring the condition of electrical equipment. A response speed of 2-5 seconds, and preferably no more than 2 seconds, can be achieved, for example, by FC operating principles based on the melting of the FC's active substance, as well as by the use of a gas-temperature thermal module (GTM).

[0095] The thermoelectric elements used in the temperature indicator of the present invention may differ in the operating principle of the temperature-sensitive component included within them. When selecting the type of temperature-sensitive component, the characteristics of each must be taken into account. Thermoelectric elements are known in the prior art to rely on a chemical reaction of their constituent substances, which begins upon reaching a certain temperature or upon melting. Prolonged exposure of thermoelectric elements based on a chemical reaction at a temperature slightly below the threshold can lead to premature activation, since the extent of the chemical reaction is determined not only by temperature but also by time.

[0096] There are thermoelectric cells based on the mechanical destruction of one of the temperature-sensitive components when a threshold temperature is reached. Typically, such thermoelectric cells have a rigid structure, which precludes the creation of flexible temperature indicators.

[0097] The most common thermoelectric cells are those based on phase transition, primarily the melting of a heat-sensitive component, due to their high precision, response speed, and ability to maintain their original appearance indefinitely at temperatures slightly below the threshold. Prior art thermoelectric cells based on the phase transition of a heat-sensitive component can be classified by the operating principle that changes the device's appearance: a change in the transparency of the heat-sensitive component upon melting, dissolution of dyes in the melted heat-sensitive material, or absorption of the melted heat-sensitive component into a porous substrate.

[0098] FCs in which the change in appearance occurs due to the dissolution of a solid dye in a melt of a fusible substance usually have a short service life due to solid-phase diffusion of the dye.

[0099] The penetration of the molten component into the porous substrate, on the one hand, ensures a high contrast of the color transition, since the color of the substrate may differ from the original color of the solid hot-melt component, but on the other hand, the crystallization of the substance in the pores of the substrate upon cooling can lead to reversibility (returnability) of the color indication.

[0100] The use of a thermo-sensitive element (TE) in a temperature indicator, the operating principle of which is based on an irreversible increase in the transparency of the heat-sensitive component due to its melting, has a number of advantages over the operating principles described above: high response accuracy due to the use of purified stable substances with a narrow range of melting points; ensuring the irreversibility of response (even with a long-term exposure of the triggered temperature indicator at a temperature below the threshold); high opacity of the heat-sensitive layer, allowing the production of flexible temperature indicators of small thickness; visibility of the triggered temperature indicator, ensured by the contrast of the color transition (e.g., white - black) due to the possibility of using a substrate of any color, in particular, black; the possibility of simplifying the assessment of the equipment condition during inspections due to the appearance of a special hazard sign or symbol (e.g., a flame sign, an exclamation mark, etc.) upon triggering of the TE.), located on the base under a layer of hot-melt material (Fig. 3-5); ensuring the possibility of registering local overheating due to the fact that only the area of ​​the TE that is heated above the threshold temperature is subject to melting, and the appearance of the remaining areas of the TE is preserved; high response speed due to the use of a thin layer of heat-sensitive component; long service life.

[0101] Based on this, the present invention prefers the use of TEs whose temperature-sensitive components operate by changing their appearance upon melting, in particular by changing their transparency. However, the invention is not limited to the use of such components, and TEs can be constructed using components operating on different principles.

[0102] When heat-sensitive materials based on melting are used for BFCs, when a threshold temperature is exceeded, the BFC changes appearance only in the area heated above the corresponding threshold temperature, while maintaining the original appearance of other areas of the BFC whose temperature did not exceed the corresponding threshold temperature. This BFC design allows for the detection of localized overheating. The boundary of the heated area is determined with high accuracy, typically within 1-2 mm. This allows for highly reliable and accurate determination of the location of a localized overheating on the monitored surface. To enhance this characteristic, it is preferable to use gas-filled hot-melt materials, which will be discussed below.

[0103] In this case, the location of the BTE relative to the temperature indicator scale becomes very important.

[0104] In preferred embodiments, the BFC is located along at least MFC i and MFC 2. The importance of the relative positions of the MFCs relative to each other and relative to the BFC can be illustrated by the following examples. When monitoring the thermal state of batteries, transformers, and cable joints, it is necessary to identify hot spots, as the temperature can vary significantly even at a short distance from the heating epicenter. This approach allows for the detection of an emergency situation even in the case of short-term localized heating that is unable to uniformly heat the monitored surface under the entire temperature indicator scale (all MFCs). For example, consider a specific case where the MFCs are arranged in order of increasing response temperatures along the vertical axis, and the BFC occupies a single area adjacent to them (Fig. 7b) and has a response temperature higher than each of the MFCs.Then, in the event of a short-term emergency heating above the BFC tripping temperature, occurring below the temperature indicator (caused, for example, by a short-circuit current), only the left, lowest-temperature MFC and partially the BFC may trip. The remaining MFCs will not have time to trip due to the localized and short-lived nature of the heating. However, the readings of such an indicator with partial BFC tripping will be more informative and reliable than the tripping of a temperature indicator with a simple MFC scale. In this case, tripping is interpreted as an emergency defect (corresponding to reality), whereas in the absence of the BFC (Fig. 7a), it would be interpreted as the initial stage of defect development (incorrect). From this perspective, the larger the area occupied by the BFC and the more uniformly it is distributed around the temperature indicator, the more informative and reliable the information obtained from its tripping.

[0105] Preferably, the minimum distance from the boundary of the BFC to each of the MFCs should be the same or comparable (in particular, the minimum distance from the boundary of the BFC to the boundary of each MFC differs by no more than 50%, preferably no more than 20%). Therefore, the use of a heat-sensitive material based on melting for the BFC, as well as the arrangement of the BFC along the temperature indicator scale, ensures: increased reliability of thermal monitoring during localized and short-term heating; allows for the determination of the location and direction of heating.

[0106] In the most preferred embodiments, the change in the appearance of at least two small temperature-sensitive elements (MTE1 and MTE2) is also associated with an increase in transparency achieved by melting one substance or a group of substances included in MTE1 and MTE2 upon reaching the corresponding threshold temperature.

[0107] The number of MFCs is not upper-limited and depends on the practical task being accomplished using the claimed temperature indicator (equipment type, required step size for determining superheat temperature, surface area of ​​the monitored object, etc.). Increasing the number of MFCs, on the one hand, allows for a more precise analysis of the temperature pattern of the monitored object, while on the other hand, it requires either an increase in the overall area of ​​the temperature indicator or a reduction in the area of ​​the MFCs themselves. Preferred embodiments of the temperature indicator contain three or four MFCs (Figs. 3 and 4), which is sufficient for solving most practical problems.

[0108] The thermal indicator may comprise two thermal elements (TE) with different response temperatures (Figs. 5 and 6). For the invention to be implemented, it is necessary and sufficient that at least one of these TTEs meets the conditions described above. The presence of a second TTE, with a response temperature different from the threshold temperature of the first TTE, will enable complex thermal monitoring tasks to be solved without replacing the thermal indicators when multiple TTEs are triggered. For example, TTE1 may have a threshold temperature equal to or lower than the minimum TTE response temperature, while TTEg may have a threshold temperature equal to or higher than the maximum TTE response temperature. In this case, the triggering of TTE1 may indicate the commissioning of the monitored object, TTEg will monitor the excess of the emergency heating limit, and the thermal indicator scale formed by the TTE will reflect temperature events during operation.

[0109] Using two BFCs with different threshold temperatures, each located at the same distance from the nearest MFCs (Fig. 6), further enhances the reliability of thermal monitoring by increasing the probability of detecting the heating location during localized heating of the monitored element. Preferably, in the initial state, the main surface of the MFC and BFC are the same, predominantly white, color. This coloration ensures maximum visibility of a partially activated device by providing a contrasting color transition upon activation of the FC.

[0110] Using a temperature indicator with a different sized TE has a number of advantages over temperature indicators with different colored TEs:

[0111] - the ability to use a color transition of only one type (the most contrasting, noticeable in operating conditions and intuitive) (for example, white - black or white - red);

[0112] - elimination of errors when inspecting equipment in poor lighting conditions, as well as by personnel with visual impairments, including the inability to distinguish the primary colors of the spectrum (color blindness);

[0113] - visibility of the color transition of the BTE from a greater distance due to its larger size;

[0114] - elimination of false interpretation of operation in the event that one of the colors of the thermal indicator is used for traditional marking (for example, blue, yellow, green, red and brown colors are widely used in the power industry for marking phases).

[0115] When a thermal indicator with a fusible element is triggered, the color of the base located underneath the element preferably appears. In some designs, each element triggers with the same color transition, preferably to black. In this particular case, if all the elements were initially white, then after each element is triggered, a white-to-black color transition occurs.

[0116] In other embodiments, the change in the appearance of the BFC upon reaching the threshold temperature differs from the corresponding change in the appearance of at least one MFC.

[0117] In another embodiment of the invention, the BTE may be made in a form different from the form of all MTEs, which will also make it easier to interpret the results of thermal monitoring using the claimed thermal indicator.

[0118] In order to increase the information content of thermal monitoring using the thermal indicator according to the present invention, in the preferred embodiments of the MFC, a thermal indicator scale is formed, which predominantly includes threshold temperatures selected from the list of 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C. The values ​​of the threshold temperatures for the operation of the MFC and the BFC may be different depending on the operational tasks. The response temperature of the BFC may be equal to the response temperature of one of the MFC, or may differ from the response temperatures of the MFC. The use of a BTE with a threshold temperature different from the threshold temperatures of an MTE increases the reliability of thermal control when using the declared temperature indicator.

[0119] If the operating temperature of the BTE is equal to the operating temperature of the lowest-temperature MTE or lower, then the operation of the BTE may indicate, for example, the commissioning of equipment, reaching or exceeding the nominal load, the beginning of the development of a defect, etc.

[0120] If the operating temperature of the BTE is equal to the operating temperature of the highest-temperature MTE or exceeds it, then the operation of the BTE may indicate, for example, an emergency, dangerous, fire-hazardous or other special condition of the monitored equipment that requires special attention from the operator.

[0121] The BFC response temperature may be between the response temperatures of the lowest and highest temperature MFCs. In this case, using the BFC allows for timely detection of the moment when additional attention to the temperature indicator scale and diagnostics are required.

[0122] To make the BTE more visible and to facilitate the detection of local overheating, in some embodiments of the invention, the area of ​​the BTE is at least 25 mm 2 , preferably not less than 100 mm 2 For the same purpose, it is preferable that the BTE occupy at least 10%, preferably at least 20%, of the total area of ​​the front surface of the temperature indicator.

[0123] It is preferable that the areas of all MFCs be comparable (specifically, differing by no more than 20%, preferably no more than 10%). This will allow for easy identification of the BFC among all the FCs and avoid focusing on individual MFCs. To facilitate interpretation of thermal monitoring data, the area of ​​the BFC should preferably be greater than the sum of the areas of all MFCs.

[0124] In particular cases, the TE may have one or more properties aimed at enhancing the technical result, in particular:

[0125] - at least one TE, preferably a BTE, may include a gas-filled hot-melt material (GFTM), preferably, the proportion of the gas phase in which is at least 10 vol.%; - at least one TE may additionally contain an absorbent material (AM);

[0126] - at least one TE may additionally contain support elements (SE);

[0127] - at least one TE may contain at least one solid organic substance with a molecular weight of less than 2 kDa;

[0128] - at least one TE changes its appearance only in the region that was heated above the corresponding threshold temperature, while maintaining the original appearance of other regions of the TE, the temperature of which did not exceed the corresponding threshold temperature;

[0129] - at least one TE may contain at least one solid organic substance containing a structural fragment C nH(2n+i), where n > 5, and is preferably selected from the group consisting of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 12; salts of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 5; alkanes containing at least 20 carbon atoms; dialkylphosphinic acids containing structural fragments C n H(2n+i) with n > 5; amides of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 5; anhydrides of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 10; fatty aliphatic alcohols containing structural fragments C n H(2n+i) with n > 14; fatty aliphatic amines containing structural fragments C n H(2n+i) with n > 17; nitriles of fatty aliphatic acids containing structural fragments C nH(2n+i) with n > 19. Preferred non-limiting examples of solid organic matter are palmitic acid, stearic acid, behenic acid, tetracosane, erucamide, stearic alcohol, cetyl alcohol, salts of saturated fatty carboxylic acids of rare earth metals, in particular lanthanum, yttrium, ytterbium, scandium.

[0130] The use of a thermal indicator (TI) ensures high accuracy and a long service life, and enables the use of minimal-thickness thermocouples while maintaining high opacity and a high luminance factor, irreversibly triggering at high speed and precision. These characteristics are achieved thanks to the TI's unique structure, which includes, in addition to a solid phase or phases, at least one of which contains a hot-melt substance or a mixture thereof, voids filled with a gas phase. Until the threshold temperature is exceeded, the gas phase within the TI is distributed predominantly uniformly. This creates multiple gas-solid interfaces at which light is refracted and reflected. This TI structure makes it opaque to at least some visible light at a thinner layer thickness than a similar substance without a gas phase.

[0131] The structure of the GTPM also provides the ability to register the boundary of the thermal heating fields of the surface of the test object by changing the appearance of only that part of the GTPM that was heated above the corresponding threshold temperatures, and maintaining the original appearance of the rest of the GTPM.

[0132] The hot-melt materials used in the present invention may contain a single active ingredient or a mixture of active ingredients. The active ingredient or mixture of active ingredients is preferably a solid organic substance or a mixture of such substances. The specific substance is selected such that upon reaching an appropriate threshold temperature of no more than 5°C, preferably no more than 2°C, it melts, resulting in a visually observable change in the appearance of the thermal indicator.

[0133] In preferred embodiments of the invention, at least one active (primary) substance of the hot-melt material has a molecular weight of less than 2 kDa (2000 amu). FCs with a low-molecular-weight active substance of the hot-melt material have a narrow melting point range, which leads to increased accuracy in detecting threshold temperature exceedances. The use of low-molecular-weight substances as active substances is only possible in a gas-fired thermoelectric module (GTM), since in the absence of a gas phase within the hot-melt material, multiple crystallization centers may form during cooling of the FC with a low-molecular-weight hot-melt substance, leading to the formation of an opaque solid and the return of the FC to its original form, i.e., to the reversibility of its operation.

[0134] The use of active substances containing one or more aliphatic hydrocarbon chains is preferable due to the fact that such organic substances have a crystalline packing in which the elongated structural fragments of linear hydrocarbons are oriented parallel to each other, which ensures the formation of predominantly flat particles such as scales, plates or fibers (Kitaigorodskii A.I. Molecular Crystals: Monograph. Moscow: Nauka. 1971. 424 p. pp. 228-232). Such crystalline packing causes the anisotropy of the solid organic substance, as a result of which the properties of the material in the direction parallel to the surface of the base and the protective coating differ from the properties of the material in the direction perpendicular to the surface of the base and the protective coating.The anisotropy of the properties of a hot-melt material affects the strength of the material under bending and mechanical stress: applying stress in directions close to perpendicular to the base surface will not lead to damage to the material (Kitaigorodskii A.I. Organic crystal chemistry: monograph. Moscow: Publishing House of the Academy of Sciences of the USSR, 1955. 558 p. pp. 134-136).

[0135] Use of aliphatic compounds with C n H(2n+i), where n > 5, is also preferable due to the fact that, due to its crystalline packaging, the heat-sensitive material exhibits the ability to bend and stretch / compress without deformation and loss of functional properties due to layer-by-layer shear of particles.

[0136] The described shape and characteristics of the active substance particles are preferred, but do not limit the claimed invention. They can also be achieved using substituted aromatic and heteroaromatic compounds. In this case, the substituents can be either long hydrocarbon fragments, which further facilitate the formation of planar oriented particles, or heteroatomic substituents, which promote layered packing of molecules, in which bulky heteroatoms are located in the interlayer space (Bokiy, G.B. Crystal Chemistry: Monograph. 3rd revised and enlarged ed. Moscow: Nauka, 1971. 401 p. pp. 362-365).

[0137] However, it should be noted that the claimed invention is not limited solely to the use of substances with a molecular weight of less than 2 kDa, which include one or more aliphatic hydrocarbon chains with a structural fragment C nH(2n+i), where n > 5. In particular, the hot-melt material may include at least one solid polymeric organic substance, selected without limitation from polyethylene, phenolic and phenol-acetylene resins, waxes, paraffins and other substances that provide an increase in the transparency of the material upon reaching the threshold temperature and possessing the necessary properties.

[0138] In preferred embodiments, the volumetric gas content of the thermal fusible composite is at least 10%, most preferably at least 50%. Using a thermal fusible composite with this volumetric gas content allows for a significant reduction in the thickness of the hot-melt material layer to ensure adequate hiding power, compared to the thickness of a non-gas-filled material required to achieve the same hiding power. To prevent delamination of the thermal fusible composite during heating due to thermal expansion of the gas phase, it is preferable for the pressure within the thermal fusible composite to be below atmospheric pressure, and for most of the pores filled with the gas phase to be non-isolated, i.e., to communicate with one another.

[0139] Using at least one gas-phase thermal indicator with the specified volumetric gas content increases the service life of the thermal indicator and improves the reliability of overheating detection by preventing the aggregation of solid organic particles separated by the gas phase. This also virtually eliminates the possibility of the thermal indicator's appearance returning to its original state when the triggered device is exposed to low temperatures and temperature fluctuations.

[0140] Increasing the volumetric gas content in the gas-fueled composite materials used also reduces their apparent density. This reduces the amount of heat required to melt the gas-fueled composite material and increases the response speed of the fuel element. In preferred embodiments of the invention, to ensure irreversibility of fuel element response, the volumetric gas content in the gas-fueled composite material during melting is reduced by at least a factor of two.

[0141] An absorbent (ABM) or microporous material can be placed between the base and the hot-melt material. In this case, when the thermoelectric element is triggered, the molten hot-melt material is absorbed or penetrated by the ABM. The use of ABM prevents partial opacity of the molten heat-sensitive layer when the triggered thermoelectric element is subjected to mechanical stress, such as bending or vibration.

[0142] One embodiment of the invention may utilize a base comprising multiple support elements (SEs) between which a hot-melt component of the TE is positioned. The TE may also contain multiple SEs located within the hot-melt phase. This protects the TE from mechanical stress (pressure, friction, increased pressure, etc.) by redistributing the load from the hot-melt phase to the support elements.

[0143] The temperature indicator may also, in particular cases, have one or more properties aimed at enhancing the technical result, in particular: be made in the form of a sticker; be elastic; be designed with the possibility of marking elements of electrical equipment or color marking of phases; the back side of the base may contain an adhesive layer of constant tack with an adhesion of at least 10 N / 25 mm to stainless steel, measured by the FINAT TM1 method after 24 hours; the base may be made of PVC, preferably of cast PVC; the TE and at least a part of the base may be covered with a protective layer, which is preferably made of PVC and is transparent to at least a part of the visible light, at least in the area of ​​the TE; the base may be partially colored using a heat-sensitive substance that reversibly changes its appearance when heated above the corresponding threshold temperature.

[0144] The thermal indicator according to the claimed invention can be implemented, in particular, in the form of a sticker, tape, clip, tip, etc. Thermal indicator stickers have found the widest application in technology due to their ease of installation, availability, and ease of use.

[0145] When the claimed invention is implemented as a sticker, the back of the base is provided with a permanent adhesive layer with an adhesion of at least 10 N / 25 mm to stainless steel, measured using the FINAT TM1 method after 24 hours, to ensure reliable contact between the temperature indicator and the monitored surface throughout the entire service life of the temperature indicator. In preferred embodiments, the adhesive layer is made using acrylic, polyurethane, rubber, silicone, PVC polymers, or adhesives based on them.

[0146] In preferred embodiments of the invention, the base of the temperature indicator is flexible and made of a thermoplastic polymer. Preferably, the base material contains halogen atoms, primarily chlorine atoms in polyvinyl chloride, most preferably cast polyvinyl chloride. The use of a halogen-containing polymer base enables the temperature indicator to visually record when at least one temperature threshold is exceeded on the surfaces of conductive components of electrical installations, since halogen-containing polymers have a dielectric strength of at least 5 kV / mm and are fire-resistant.

[0147] Polymeric materials containing halogen atoms in their structure exhibit some of the highest flexibility and elasticity among known polymers. The introduction of halogen atoms into the monomers used as feedstock for polymerization disrupts their symmetry and creates multiple chiral centers in the polymer. Polymerization or polycondensation of such monomers, either with each other or with other halogen-containing or halogen-free monomers, results in the formation of polymer chains with a large number of stereocenters. Regular polymers obtained from non-halogenated monomers lacking chiral centers tend to form crystalline structures, which reduces their elasticity, while the large number of diastereomers formed during halogenation of the monomers imparts stereochemical disorder to halogenated polymers, which prevents crystallization.Thus, halogen-containing polymeric materials possess high elasticity and flexibility due to their chemical structure, which is determined by the presence of halogen atoms in the polymer structure. Furthermore, halogen-containing materials exhibit good adhesion and low flammability, which further enhances the safety of the device.

[0148] The use of a protective layer not only protects the heat-sensitive material from adverse environmental influences but also prevents it from leaking during activation. A sealed protective layer also allows for the creation of under or overpressure within the hot-melt material. Preferably, the protective layer is made of elastic polymeric materials, particularly PVC or cast PVC, and is transparent to at least some visible light, at least in the area of ​​the TE.

[0149] The use of thermoplastic polymers as a base material and / or protective layer allows for the effective and hermetically sealed connection of the protective layer and the base, for example, by welding.

[0150] Using elastic materials for the base and protective layer ensures the overall elasticity of the device, which ensures a tight fit of the thermal indicator to surfaces with complex geometries, including those with small radii of curvature, such as conductive elements of electrical equipment.

[0151] In specific embodiments, information elements may be applied to the base and / or protective layer, including information for marking electrical equipment components or color coding of phases. Specifically, information elements applied to the front surface of the base and / or protective layer may include inscriptions containing color, alphabetic, numeric, or alphanumeric marking information. In one case, information elements on the base and / or protective layer may contain information about the end-of-life date of the device. Also, when the BTE is triggered, an additional information symbol may appear, such as an exclamation mark, a flame image, etc. (Figs. 3-5).

[0152] The base and / or protective layer may also be colored to comply with established electrical equipment marking standards. The above features serve to give the device for detecting threshold temperature exceedance the properties of electrical equipment marking elements.

[0153] To increase the visibility of both the temperature indicator itself and the fact of its operation, and, as a consequence, to further increase the safety of equipment operation, the base may have reflective or luminescent properties.

[0154] Also, the base or some portion of it can be painted using a substance capable of reversibly changing its appearance upon heating. For example, a layer of heat-sensitive paint with the above-mentioned properties can be applied to the front surface.

[0155] The presence of a substance capable of reversibly changing its appearance when heated allows personnel to be informed not only of past temperature threshold exceedances but also of overheating events during the inspection. The activation of such a substance during an inspection indicates that the equipment is currently in emergency mode and may pose a potential hazard. Thus, the presence of a substance capable of reversibly changing its appearance when heated further enhances the safety of equipment operation.

[0156] The presented examples describe only particular variants of using the device according to the present invention and do not limit its functionality and scope of application.

[0157] Brief description of the drawings

[0158] Fig. 1 - a temperature indicator according to the present invention, including two MFCs forming a temperature indicator scale, and one BFC, in an embodiment in which the BFC has a lower threshold temperature than the MFC, the BFC and MFC have a color transition (white-black).

[0159] Fig. 2 - operation of a multi-temperature thermal indicator, known from the prior art, with four different temperature-sensitive elements for recording threshold temperatures (60 °C, 70 °C, 80 °C, 90 °C) with a gradual increase in temperature.

[0160] Fig. 3 - a temperature indicator according to the present invention, including three MFCs forming a temperature indicator scale, and one BFC, in an embodiment in which the BFC has a higher threshold temperature than the MFC, all FCs have the same color transition (white-black), and in the area of ​​the BFC, in addition to the numerical value of the threshold temperatures, information signs warning of danger are additionally located.

[0161] Fig. 4 is a temperature indicator according to the present invention, including four MFCs forming a temperature indicator scale, and one BFC, in an embodiment in which the BFC has a higher threshold temperature than the MFC, all FCs have the same color transition (white-black), and in the area of ​​the BFC, in addition to the numerical value of the threshold temperatures, information signs warning of danger are additionally located.

[0162] Fig. 5 is a temperature indicator according to the present invention, comprising three MFCs forming a temperature indicator scale, and two BFCs, in an embodiment in which one BFC1 has a lower threshold temperature than the MFC, and the second BFCg has a higher threshold temperature than the MFC, BFC1 has a white-to-black color transition, the BFCg has a white-to-black color transition, and the MFCs have a white-to-red color transition. In the BFCg area, in addition to the numerical value of the threshold temperature, information signs warning of danger are additionally located.

[0163] Fig. 6 is a temperature indicator according to the present invention, comprising four MFCs forming a double temperature indicator scale, and two BFCs, in an embodiment in which one BFC1 has a threshold temperature lying between the threshold temperatures of the MFCs, and the second BFCg has a higher threshold temperature than the MFC, all FCs have the same color transition (white-black). The base is colored using a reversible temperature-sensitive material.

[0164] Fig. 7 - activation of the thermal indicator during a short-term emergency heating that occurred to the left of the thermal indicator.

[0165] Fig. 8 - layered structure of a thermal indicator made in the form of a sticker, in various embodiments (using a thermal insulation material, absorbent material).

[0166] Fig. 9 - structure of the gas turbine engine with and without support elements.

[0167] Detailed description of the drawings

[0168] Fig. 1 shows a temperature indicator according to the present invention, including two MFC 3, forming a temperature indicator scale, and one BFC 4, in an embodiment in which the BFC has a lower threshold temperature than the MFC, the BFC and the MFC have a color transition (white-black). The base 1 and / or the protective layer are colored yellow for marking the phases of the electrical equipment. Information elements showing the numerical values ​​of the threshold temperatures 5 of the MFC and the BFC are located on the base 1 and / or the protective layer, next to the corresponding MFC and BFC. 1a - initial appearance of the temperature indicator, 1b - partially triggered temperature indicator after exceeding the threshold temperature of the BTE, 1c - partially triggered temperature indicator after exceeding the threshold temperature of the MTE1, 1g - fully triggered temperature indicator after exceeding the threshold temperature of the MTE1, 1d - triggered temperature indicator after cooling to a temperature below the threshold temperature of the BTE, with the indicated distance a between the boundaries of the MTE and the BTE.

[0169] Fig. 2 shows the operation of a multi-temperature thermal indicator, known from the prior art, with four different temperature-sensitive elements 2 applied to a base 1 for recording threshold temperatures (60 °C, 70 °C, 80 °C, 90 °C) with a gradual increase in temperature.2a - the initial appearance of the temperature indicator before exceeding the threshold temperature of the first temperature-sensitive element, which is classified as the absence of a defect, 2b-2g - a partially triggered temperature indicator after exceeding the threshold temperature of the first, second and third TE, respectively, such a triggering of the temperature indicator is classified as the development of a defect, 2d,e - a fully triggered temperature indicator after exceeding the threshold temperature of the fourth TE and subsequent cooling to a temperature below the threshold temperature of the first TE, with preservation of the external appearance of the temperature indicator, such a triggering of the temperature indicator is classified as an emergency defect, with the specified distance a between the boundaries of the MTE and BTE.

[0170] Fig. 3 shows a temperature indicator according to the present invention, including three MFC 3, forming a temperature indicator scale, and one BFC 4, in an embodiment in which the BFC has a higher threshold temperature than the MFC, all FC have the same color transition (white-black), and in the area of ​​the BFC, in addition to the numerical values ​​of the threshold temperatures 5, information signs warning of danger 6 are additionally located. The base 1 and / or the protective layer are painted yellow for marking the phases of the electrical equipment. Za is the initial appearance of the temperature indicator, 36 is a fully activated temperature indicator after exceeding the threshold temperature of the BFC, with the indicated distance a between the boundaries of the MFC and the BFC.

[0171] Fig. 4 shows a temperature indicator according to the present invention, including four MFC 3, forming a temperature indicator scale, and one BFC 4, in an embodiment in which the BFC has a higher threshold temperature than the MFC, all FC have the same color transition (white-black). Information elements showing the numerical values ​​of the threshold temperatures 5 of the MFC are located on the base 1 and / or the protective layer, next to the corresponding MFC, and in the area of ​​the BFC there is an information element showing the numerical value of the threshold temperature 5 of the BFC, and additionally there are information signs warning of danger 6. The base 1 has retroreflective and / or luminescent properties. 4a - the initial appearance of the temperature indicator, 4b - a fully activated temperature indicator after exceeding the threshold temperature of the BFC.

[0172] Fig. 5 shows a temperature indicator according to the present invention, including three MFC 3, forming a temperature indicator scale, and two BFC 4, in an embodiment in which one BFC1 has a lower threshold temperature than the MFC, and the second BFCg has a higher threshold temperature than the MFC, BFC1 has a white-green color transition, the BFCg has a white-black color transition, the MFCs have a white-red color transition. Information elements showing the numerical values ​​of the threshold temperatures of the 5 MFCs are located on the base 1 and / or the protective layer, next to the corresponding MFCs, and in the BFC area, information elements showing the numerical values ​​of the threshold temperatures of the 5 BFCs are located. In the BFC area, in addition to the numerical value of the threshold temperature 5, information signs warning of danger 6 are additionally located.5a - initial appearance of the temperature indicator, 5b - partially triggered temperature indicator after exceeding the threshold temperature of the BTEc, 5v - partially triggered temperature indicator after exceeding the threshold temperatures of the MTE, 5g - fully triggered temperature indicator after exceeding the threshold temperature of the BTEg.

[0173] Fig. 6 shows a temperature indicator according to the present invention, including four MFC 3, forming a double temperature indicator scale, and two BFC 4, in an embodiment in which one BFC1 has a threshold temperature lying between the threshold temperatures of the MFC, and the second BFCg has a higher threshold temperature than the MFC, all FC have the same color transition (white-black). The base is painted using reversible heat-sensitive material 7. 6a - initial appearance of the temperature indicator, 6b - partially triggered temperature indicator after exceeding the threshold temperatures of MFC1 and the reversible heat-sensitive material, 6c - partially triggered temperature indicator after exceeding the threshold temperature of MFC1, MFC2 and BFC1, 6g - fully triggered temperature indicator after exceeding the threshold temperature of all MFCs and BFCs, 6d - temperature indicator after cooling to a temperature below the temperature of the reversible heat-sensitive material, with the indicated distance a between the boundaries of the MFC and BFC.

[0174] Fig. 7 shows the operation of a temperature indicator during a short-term emergency heating that occurred to the left of the temperature indicator. 7a is a multi-temperature temperature indicator known from the prior art, with local heating to the left of the temperature indicator, above the highest threshold temperature of a given temperature indicator; 7b is a temperature indicator according to the present invention, including three MFCs 3, forming a temperature indicator scale, and a BFC 4, with local heating to the left of the temperature indicator, above the BFC operation temperature.

[0175] Fig. 8 shows the layered structure of a temperature indicator made in the form of a sticker, including a base 1, having a yellow color, the back side of which is covered with an adhesive layer of constant tack 8 and protected by a release 9, two MFCs 3 and one BFC 4, a protective layer 10 covering the FC and attached to the base in areas free of FC. 7a - with the use of a GTPM (the structure is not shown) and the coloring of the base in the areas under the MFC in black, and in the area under the BFC in red, 76 - with the use of a GTPM (the structure is not shown) and the use of an absorbent material 11 in black in the area of ​​all FC.

[0176] Fig. 9 shows the structure of the GTPM, including particles of solid organic matter 12 and voids 13 filled with a gas phase (Fig. 9a), as well as support elements 14 uniformly distributed throughout the volume of the GTPM (Fig. 9b).

[0177] Implementation of the invention

[0178] Selecting the base of the device

[0179] The base 1 of the claimed irreversible temperature indicator is preferably made of polymeric materials, but the use of materials such as paper, cellulose, and woven materials is not excluded. The base material 1 should preferably be elastic and flexible to ensure the possibility of installing the temperature indicator on a surface with complex geometry, including surfaces with a small radius of curvature. Halogen-containing polymeric materials are preferably used in the claimed invention without limitation, in particular chlorine-containing polymers, for example, vinyl chloride copolymers, namely: copolymer C-15 (a copolymer of vinyl chloride and vinyl acetate), copolymer VHVD-40 (a copolymer of vinyl chloride and vinylidene chloride), polyvinyl chloride (PVC), cast PVC, polyvinylidene fluoride PVDF, fluoroplastic M-40, as well as polyesters with the addition of 6.5% hexabromocyclododecane or polyesters modified with 15% trichloroisopropyl phosphate.

[0180] When using a halogen-containing polymer base, the dielectric strength of the temperature indicator is preferably at least 5 kV / mm, which is preferred for use in the power industry. Halogen-containing materials also have low flammability. When selecting the base material, consider its melting or decomposition temperature, which should be higher than the maximum response temperature of the temperature indicator.

[0181] In one embodiment, the temperature indicator may be implemented as a sticker (Fig. 8). In this case, the back of the base 1 is coated with permanent adhesive 8 and protected by a release 9. Acrylic, polyurethane, rubber, silicone, and PVC polymer-based adhesives can be used as the permanent adhesive layer. Preferably, the adhesion of the adhesive layer to stainless steel, measured by the FINAT TM1 method after 24 hours, is at least 10 N / 25 mm.

[0182] In other embodiments, the base 1 of the temperature indicator may be a hollow cylinder, with or without a slit, to produce devices in the form of temperature indicator clips, cambric sleeves, or tips. In this case, the base 1 is preferably made of polymeric materials with elasticity and flexibility to ensure secure attachment to wires and other round electrical components without the use of adhesives or other fastening methods.

[0183] When manufacturing a temperature indicator, it is preferable to use a protective layer 10, which protects the FC and the device itself from external environmental influences, humidity, UV radiation, and mechanical damage, thereby increasing the device's service life. The material of the protective layer 10 is preferably selected from transparent elastic polymers, preferably halogen-containing polymers, in particular polyvinyl chloride, most preferably cast polyvinyl chloride. Flexible elastic polymer films made of polyvinyl chloride, polyurethane, polyurea, and other polymers are preferred as materials for the protective layer 10.

[0184] Base 1 and / or protective layer 10 (if present) may have reflective or luminescent properties to increase the visibility of both the temperature indicator itself and the fact of its operation to improve the safety of operation of the equipment on which the temperature indicator is installed.

[0185] In specific cases, base 1 and / or protective layer 10 (if present), or part thereof, may be colored in accordance with the requirements for marking cable phases, installation wires, harnesses, and other electrical equipment components. The color of base 1 may be initially selected in accordance with GOST 28763-90, which establishes, among other things, color coding in electrical engineering.

[0186] To enhance the contrast of the color transition, the base in the TE zone can be painted. Information, including threshold temperature values ​​5, the device's expiration date, and other data, can also be applied to the surface of the base 1 and / or protective layer 10 (if present).

[0187] In one embodiment, a base 1 and / or a protective layer 10 (if present) may be used, which include multiple support elements (SE), between which at least part of the heat-sensitive material is located.

[0188] Manufacturing of heat-sensitive material for fuel cells

[0189] The claimed invention can utilize various thermoelectric cells whose operating principle is based on a change in appearance upon reaching a threshold temperature. It is preferable to use a single thermoelectric cell type in a single temperature indicator; however, thermoelectric cells operating on different operating principles can be used if necessary. The preferred method is to use thermoelectric cells whose temperature-sensitive components operate by changing their appearance upon melting, specifically by changing their transparency.

[0190] In certain cases, the change in appearance of at least one fuel element, preferably a biofuel element, and most preferably all microfuel elements and biofuel elements, upon reaching the appropriate threshold temperature is associated with increased transparency achieved by melting the substance or group of substances comprising the fuel element. When a thermal indicator with such fuel elements is triggered, the color of the base 1 located beneath them is revealed. Depending on the color of the base beneath the fuel element, the same or different color transitions may occur upon each activation. Preferably, the base beneath all fuel elements is painted black. In this case, all fuel elements are preferably white in their initial state, thereby ensuring a visually observable "white-to-black" transition upon activation.

[0191] At least one FC, preferably BFC 4, most preferably all MFC 3 and BFC 4, may include: a gas-filled hot-melt material (GFTM), preferably, the proportion of the gas phase in which is at least 10 vol.%; an absorbent material; support elements; at least one solid organic substance with a molecular weight of less than 2 kDa; at least one solid organic substance containing a structural fragment C n H(2n+i), where n > 5, and is preferably selected from the group consisting of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 12; salts of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 5; alkanes containing at least 20 carbon atoms; dialkylphosphinic acids containing structural fragments C n H(2n+i) with n > 5; amides of fatty aliphatic acids containing structural fragments C nH(2n+i) with n > 5; anhydrides of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 10; fatty aliphatic alcohols containing structural fragments C n H(2n+i) with n > 14; fatty aliphatic amines containing structural fragments C n H(2n+i) with n > 17; nitriles of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 19.

[0192] In particular embodiments, the solid organic substance / a TE is, without limitation, selected from the group consisting of: yttrium caproate, yttrium behenate, yttrium undecanoate, yttrium laurate, yttrium tridecanelaurate, yttrium tridecanepentadecanate, yttrium tridecanoate, yttrium pentadecanoate, yttrium palmitate, ytterbium caprylate, lanthanum palmitate, lanthanum nonadecynate, lanthanum caproate, erbium undecanate, zinc nonadecanoate, zinc palmitate, zinc caproate, zinc myristicate, zinc stearate, cadmium laurate, cadmium laurinmyristate, lead caproate, lead stearate, lead laurate, lead laurinmyristate, stearate copper, calcium stearate, lithium stearate, stearic acid, lauric acid, docosanoic acid, eicosanoic acid, crotonic acid, arachidic acid, myristic acid, palmitic acid, adipic acid, octanoic acid, capric acid, tricosanic acid, tetratriacontanoic acid, 2,3-dimethylnonanoic acid, brassidic acid,2-methyl-2-dodecenoic acid, eleostearic acid, behenolic acid, behenic acid, oleamide, stearamide, lauramide, erucylamide, capric amide, myristic amide, caprylic amide, palmitic anilide, salicylic anilide, beta-naphthylamide caproic acid, enanthic phenylhydrazide, hexylamide, octacosylamide, N-methylheptacosylamide, salicylamide, hexadecanol, ecucamide, 1-docosonol, trilaurin, tricosylamine, dioctadecylamine, T4, T4-dimethyloctylamine, dioctylphosphinic acid, tritriacontane, tetracosane, stearyl alcohol, cetyl alcohol, chloride stearic anhydride, palmitic anhydride, stearic and acetic anhydride, lauric anhydride or mixtures thereof with a melting point that differs from the threshold temperature by no more than 5 °C.,

[0193] When using a gas-fueled thermocouple (GFPM) in at least one fuel element, it is preferable that upon reaching the appropriate threshold temperature, the volume fraction of gas within the GFPM decreases by at least a factor of two. This ensures irreversibility of the change in transparency of the GFPM when the appropriate threshold temperature is exceeded. Using at least one fuel element incorporating a GFPM with a volume fraction of gas of at least 10% also extends the service life of the temperature indicator and improves the reliability of overheating detection by preventing the aggregation of solid organic matter through the gas phase.Also, the greater the proportion of gas in the gas-filled thermocouple, the higher the initial refractive index, the more contrasting the change in appearance due to a strong decrease in the refractive index when the corresponding threshold temperature is exceeded, and the more significant the separation of the gas and other phases after the activation of the gas-filled thermocouple, which eliminates the possibility of the gas-filled thermocouple returning to its original gas-filled state when the activated temperature indicator is maintained at low temperatures and with temperature fluctuations.

[0194] The process of manufacturing a fuel cell including a gas-temperature thermoelectric module is described in detail in a number of the authors’ patents, in particular, in patent RU 2800396 C1, published on July 21, 2023, and can be used to create a temperature indicator according to the present invention.

[0195] To produce at least one HTPM, the solid organic substance is ground in a ball mill to a particle size of 2-3 µm. A liquid phase consisting of water or an organic solvent with a boiling point below 180°C is added, and the resulting suspension is mixed, preferably with periodic dispersion of the mixture under air access until the mixture's density remains constant. The liquid phase is preferably water or an organic solvent in which the solubility of the solid organic substance of the HTPM does not exceed 100 g / kg.

[0196] In preferred embodiments of the invention, the liquid phase is added in an amount of at least 50 wt.%, most preferably from 50 wt.% to 90 wt.%.

[0197] The difference in density between the liquid phase and the solid organic matter is preferably less than 0.2 g / cm 3. For this purpose, the liquid phase can be selected without limitation from the group consisting of isopropanol, water, methanol, 1-propanol, isobutanol, ethylene glycol monomethyl ether, 1-butanol, acetonitrile, acetic acid, hexane, heptane, octane, nonane, 1,1,1-trifluoroethanol, 1, 1,1, 3,3,3-hexafluoroisopropanol, NM-dimethylformamide, toluene, xylene, ethanol, butyl acetate, acetone and mixtures thereof. The resulting suspension or paste is applied to the base and / or protective layer and / or absorbent material and dried under the action of dry air, temperature or vacuum.

[0198] This method produces a gas-fueled composite material (GPM) containing a solid organic substance, preferably in the form of particles with uniformly distributed gas-filled voids. Depending on the nature of the solid organic substance, the resulting particles can predominantly be grains, crystals, fibers, flakes, or agglomerates thereof.

[0199] In particular cases, at least one HTPM further comprises a polymer binder that is transparent to at least some visible light. In some embodiments, the binder ensures adhesion of the HTPM to the base or absorbent material. In this case, the crushed solid organic substance is suspended in a solution of a binder that is transparent to at least some visible light in a solvent with a boiling point below 150°C. In preferred embodiments of the invention, to ensure a glazing effect on the solid organic substance, the binder is present in the resulting HTPM in an amount of 1-30% by weight.

[0200] The transparent polymer binder may be selected without limitation from the group consisting of phenol-formaldehyde resin, butyl methacrylate resin, melamine-formaldehyde resin, polyvinyl butyral, polybutyl methacrylate, polyisobutyl methacrylate, polybutyl acrylate, phenoxy resin, polystyrene-acrylic emulsion, polyolefin, polystyrene, polyacrylate, polyethersulfone, polyethylene, polypropylene, polystyrene, polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, polyisoprene, polypropylene, polybutadiene, polyisobutylene, polyvinyl acetate, polymethacrylate, ethyl cellulose, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polycaprolactone, polyethylene terephthalate resin, polybutylene terephthalate resin, polyamide resins, polyvinylidene fluoride, polyester, polyester resins, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, nitrocellulose, carboxymethyl cellulose, gelatin, agar-agar, casein, gum arabic, polyvinyl alcohol, polyethylene oxide or mixtures thereof,but not limited to them.,

[0201] At least one FC, preferably a BFC, most preferably all MFCs and BFCs, are selected in such a way that upon reaching the corresponding threshold temperature in the range of no more than 5 °C, preferably no more than 2 °C, the response speed is no more than 5 seconds, preferably no more than 2 seconds.

[0202] In various embodiments, the FC is selected in such a way that the threshold temperatures, in particular for the MFC, can be selected from the range from 50 to 210 °C. In this case, the numerical values ​​of the threshold temperatures of the FC can be selected, in particular, from the group of 50 °C, 55 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C. For a device containing three different MFCs (MFC1, MFC2, MFC3), the threshold temperatures may be 50 °C, 55 °C, 60 °C, or 50 °C, 60 °C, 70 °C, or 50 °C, 70 °C, 80 °C, or 60 °C, 70 °C, 80 °C, or 60 °C, 80 °C, 100 °C, or 60 °C, 90 °C, 110 °C, or 70 °C, 80 °C, 90 °C, or 70 °C, 90 °C, 110 °C, or 70 °C, 100 °C, 120 °C, or 70 °C, 110 °C, 130 °C, or 80 °C, 90 °C, 100 °C, or 80 °C, 120 °C, 140 °C, or 80 °C, 120 °C, 150 °C, or 90 °C, 100 °C, 110 °C, or 90 °C, 110 °C, 130 °C, or 100 °C, 120 °C, 140 °C.

[0203] For a device containing four different MFCs (MFC1, MFC2, MFC3, MTED), the threshold temperatures may be 50 °C, 55 °C, 60 °C, 70 °C, or 50 °C, 60 °C, 70 °C, 80 °C, or 50 °C, 70 °C, 90 °C, 110 °C, or 60 °C, 70 °C, 80 °C, 90 °C, or 60 °C, 70 °C, 80 °C, 100 °C, or 60 °C, 80 °C, 90 °C, 110 °C, or 70 °C, 80 °C, 90 °C, 100 °C, or 70 °C, 90 °C, 100 °C, 120 °C, or 70 °C, 90 °C, 110 °C, 130 °C, or 80 °C, 90 °C, 100 °C, 110 °C, or 80 °C, 100 °C, 120 °C, 140 °C, or 80 °C, 100 °C, 120 °C, 150 °C.

[0204] The tripping temperatures of the MFC and BFC may vary depending on operational tasks. The tripping temperature of a BFC may be equal to the tripping temperature of one of the MFCs, or it may differ from the tripping temperatures of the other MFCs. In particular, the threshold temperature of a BFC may be 30°C higher than the highest-temperature MFC. A temperature indicator may contain more than one BFC. In this case, the threshold temperature of the second BFC may also be equal to the threshold temperature of one of the MFCs, or it may be higher or lower than the threshold temperature values ​​of the MFCs.

[0205] In specific embodiments of the invention, one or more TEs may contain supporting elements uniformly distributed within the temperature-sensitive material, which are added to it during its manufacture. Supporting elements may be made of a material with a melting point higher than the TE's response temperature. Polymeric materials, particularly halogen-containing polymers such as polyvinyl chloride and cast polyvinyl chloride, as well as glass, ceramics, metals, non-metals, and products based on them, such as meshes, fibers, microspheres, woven or non-woven materials possessing the above-mentioned characteristics, may be used as supporting elements.

[0206] In specific implementations of the invention, one or more TEs may include a VM that absorbs the molten hot-melt material during its activation. The use of a VM provides additional enhancement of the technical result due to the irreversibility of the TE's activation. Furthermore, the VM can perform the functions of the TE described above.

[0207] In certain cases, the EM is made of porous or absorbent materials, preferably microporous materials. EM can be selected without limitation from paper, microcellulose, wool, silk, felt, cotton, linen, molecular sieves, zeolites, silica gel, aerosil, microspheres, and ceramics. Microporous materials with a pore diameter of no more than 2 µm are most preferred. The EM can be colored. In this case, the color of the EM will appear upon activation. Alternatively, the EM can become transparent upon absorption of a melt (silica gel, aerosil). In this case, the color of the base will appear upon activation of the TE.

[0208] General technology for manufacturing a temperature indicator

[0209] A partially or completely painted or unpainted base is covered with a protective polymer film, excluding the area where the MTE1 is to be located. The MTE1 is applied using the selected method, depending on the type of heat-sensitive material used. The film is then removed, and the procedure is repeated for applying the remaining MTE3 and BTE4. The area of ​​the BTE must be at least twice the area of ​​each MTE. The shape of the BTE and MTE may be the same or different, depending on the requirements for the temperature indicator. The area of ​​the base free of the TE can be covered with a heat-sensitive material 7, which reversibly changes its appearance when heated above the appropriate threshold temperature.

[0210] When MTE 3 and BTE 4 are arranged relative to each other on the surface of base 1, the following requirements are preferably met: the area of ​​the BTE is at least 25 mm 2, preferably not less than 100 mm 2 ;

[0211] The BFC occupies no less than 10%, preferably no less than 20%, of the total area of ​​the temperature indicator; the areas of the MFC differ by no more than 20%, preferably no more than 10%; the area of ​​the BFC is greater than or equal to the total area of ​​all MFCs;

[0212] The MFCs are arranged sequentially in order of increasing threshold temperatures to form a temperature indicator scale; the distance from the boundary of the MFC to each of the MFCs differs by no more than 50%, preferably by no more than 20%.

[0213] The total surface area of ​​the substrate containing the TE preferably comprises between 3% and 97% of the surface area of ​​the substrate, preferably at least 30%. This allows for the detection of activated temperature indicators from a distance, as well as the detection of spot heating over a large surface area of ​​equipment. After application of all the TEs, in some embodiments of the invention, the temperature indicator is coated with a protective layer 10 that is transparent to at least some visible light, at least in the region of the TEs.

[0214] How a temperature indicator works

[0215] The temperature indicator according to the claimed invention operates as follows. In the initial state, all TEs have the same, predominantly white, color. Until the entire surface of the temperature indicator or its individual sections located under the TE is heated to the threshold value of the lowest temperature TE (Ti), the original appearance of the temperature indicator is preserved. When the surface is heated above the threshold temperature of the lowest temperature TE (Ti), an irreversible change in the appearance of this TE occurs. At the same time, other TEs with threshold temperatures Tg . Tp > Ti retain their original appearance. A further increase in the temperature of the surface on which a fragment of the temperature indicator is located to a temperature Tg . Tp leads to sequential irreversible operation of the corresponding TEs with threshold temperatures Tg . Tp. Moreover, if the maximum surface temperature is below at least one of the threshold temperatures T п, the corresponding TEs will retain their original appearance. Upon subsequent cooling, the surfaces of the areas with the activated TEs retain their appearance, preventing the entire temperature indicator from returning to its original state. This ensures the ability to visually record temperature exceeding the threshold, both at the moment of overheating and after a long period of time.

[0216] When heat-sensitive materials are used in thermal control devices (TCDs), whose operation is based on the floating of a hot-melt component, spot heating of the monitored surface to the TCD trigger temperature causes a partial change in its appearance only in the area heated above the threshold temperature, while the remaining unheated areas retain their original appearance. In this case, to increase the reliability of thermal monitoring, it is preferable to position the TCD along the temperature indicator scale.

[0217] Preferably, the use of such thermal elements ensures that the temperature indicator retains its original appearance when the device is cooled to 20°C and maintained at this temperature for at least one month, preferably one year or more. In preferred embodiments, the temperature indicator has a service life of at least five years, preferably at least ten years. The temperature indicator according to the claimed invention can find application in electrical engineering for monitoring the surface temperature of electrical equipment, such as complete switchgear units, BRNO boxes, electrical panels, etc., and their individual components (wires, cables, contact connections, etc.), as well as other industrial or domestic devices that require temperature monitoring.

[0218] By visually inspecting a temperature indicator mounted on equipment, it is possible to reliably and with high accuracy register the fact of a temperature increase on the entire surface or on a section thereof, exceeding at least one threshold value, and the combination of several MFCs and at least one BFC on one temperature indicator will ensure an increase in the safety of the operation of electrical equipment, due to the ease of interpretation of the results of temperature indicator control, without loss of its information content.

[0219] Below are presented preferred embodiments of the claimed invention, which are illustrative and in no way limit the scope of the requested legal protection.

[0220] Examples

[0221] General technology of manufacturing the device

[0222] The examples discussed use of temperature-sensitive materials based on phase transition and changing their appearance by increasing transparency upon reaching the phase transition temperature. All thermoelectric cells were manufactured using the method described in the previous section. The examples consider device designs in the form of a sticker, but other implementations of the claimed device are also possible. Halogen-containing polymer films with an adhesive layer providing an average adhesion value (FINAT TM 1, after 24 hours, stainless steel) of 10N / 25mm were used as the base. Acrylic adhesive was used as the adhesive layer.

[0223] It is also possible to use heat-sensitive materials based on mechanical destruction of the heat-sensitive component, a chemical reaction, or the mixing of components during melting and the absorption of the hot-melt components into the substrate. In all cases, the general principle of manufacturing and operation of the device remains the same.

[0224] The area of ​​the substrate's face that should not be exposed to the first thermoelectric element was covered with a protective polyethylene film of the required shape and coated several times with a roller coated with the appropriate heat-sensitive material. The number of passes varied from 3 to 20, until a uniform, opaque coating was achieved. After the layer had completely dried, the protective film was removed, and the procedure was repeated sequentially to apply the second and subsequent thermoelectric elements. When using phase-transition thermoelectric materials that change their transparency upon reaching threshold temperatures, the areas of such thermoelectric materials are initially white.

[0225] Example 1.

[0226] We made two temperature indicators measuring 40*60 mm (2400 mm) 2) with three MFCs and one BFC applied to the base as shown in Fig. 3. A heat-sensitive composition with a threshold temperature of 60 °C was used as MFC1, a heat-sensitive composition with a threshold temperature of 70 °C was used as MFC2, a heat-sensitive composition with a threshold temperature of 80 °C was used as MFC3, and a heat-sensitive composition with a threshold temperature of 100 °C was used as BFC. The BFC has a rectangular shape and a size of 17*56 mm (952 mm 2 ), which accounts for 40% of the total surface area of ​​the temperature indicator. Each MFC is square and measures 17 x 17 mm (289 mm) 2 ). Thus, the total area of ​​all MFCs is 867 mm 2 , which is smaller than the area of ​​the BFC. The MFCs are arranged in order of increasing threshold temperatures, forming a temperature-indicating scale. The BFC is located along all the MFCs. The distance a between the boundary of the BFC and the boundaries of each MFC is the same and is 2 mm (Fig. 3b).

[0227] One temperature indicator was installed on a heating element at room temperature. The heating element was then heated in a controlled, uniform manner at a rate of 5°C / min to a temperature of 60°C with a specified accuracy. Heating was stopped, and the activation of MTE1 was recorded by visually recording a white-to-black color transition. The surface was then sequentially uniformly heated to temperatures of 70°C, 80°C, and 100°C, and the activation of the corresponding device zones was recorded by visually recording a white-to-black color transition. The activation time and change in appearance for MTE1 was 2 seconds, for MTE2 – 1 second, for MTE3 – 2 seconds, and for BTE – 1 second. After the device had cooled to room temperature, the changed appearance of all zones containing heat-sensitive materials was visually recorded.

[0228] The second temperature indicator was mounted at room temperature on the surface of a thin metal plate. A spot heating source was applied to the back of the plate, close to one of its edges, and heated in a controlled manner at a rate of 5°C / min to a temperature of 100°C. The change in the appearance of the BFC portion located closest to the heat source was recorded by visually observing a white-to-black color transition, while the original appearance of the BFC portion located farthest from the heat source was maintained. The change in the appearance of MFC1 and MFC2, located closer to the heat source, was also recorded, while the original appearance of MFC3, located farther from the heat source, was maintained. After the device cooled to room temperature, the changed appearance of the BFC portion, MFC1, and MFC2 was visually observed to persist.Thus, when using a TE whose operation is based on the melting of a heat-sensitive component, as a result of partial activation of the device due to point heating of the surface and the location of the heat source on the side of the device, the location of the activated part of the BTE, as well as the partial activation of the MTE, allows not only to determine the maximum temperature to which heating occurred, but also to assume the location of the heat source.

[0229] Example 2.

[0230] We made a temperature indicator measuring 50*100 mm (5000 cm) 2) with four MFCs and two BFCs applied to the base as shown in Fig. 6. Before applying the FCs, the base was coated with Tempilaq pigmented green reversible thermal paint with an appearance change temperature of 58 °C. A heat-sensitive composition with a threshold temperature of 60 °C was used as MFC1, a heat-sensitive composition with a threshold temperature of 70 °C was used as MFCg, a heat-sensitive composition with a threshold temperature of 90 °C was used as MFCz, a heat-sensitive composition with a threshold temperature of 100 °C was used as MFC4, a heat-sensitive composition with a threshold temperature of 80 °C was used as BFC1, and a heat-sensitive composition with a threshold temperature of 110 °C was used as BFC2. The BFCs have the same rectangular shape and size of 20 * 40 mm (800 mm 2 ), which is 16% of the total surface area of ​​the temperature indicator for each BTE. Each MTE has a round shape with a diameter of 20 mm (314 mm 2). The MFCs are arranged in pairs in order of increasing threshold temperatures, forming a temperature indicator scale. The BFCs are arranged along the MFCs so that two zones can be distinguished on the temperature indicator, in which the distances between the boundaries of the BFC and the MFCs closest to them are equal (the zone containing MFC1, MFC2, and BFC1, as well as the zone containing MFC3, MFC4, and BFC2). The minimum distance a between the boundary of BFC1, located in the center, and the boundaries of each of the MFCs is the same and amounts to 3 mm (Fig. 6d).

[0231] The thermal indicator was mounted on a heating element at room temperature, which was then heated in a controlled, uniform manner at a rate of 5°C / min to a temperature of 60°C with a specified accuracy. Heating was stopped, and the activation of MTE1 was recorded by visually recording the white-to-black color transition, as well as the activation of the thermal paint with a green-to-red color transition. The surface was then sequentially uniformly heated to temperatures of 70°C, 80°C, 90°C, 100°C, and 110°C, and the activation of the corresponding device zones was recorded by visually recording the white-to-black color transition. The activation time and change in appearance for MTE1 was 2 seconds, for MTE2 - 1 second, for MTE3 - 2 seconds, for MTE4 - 4 seconds, for BTE1 - 3 seconds, and for BTE2 - 1 second.After final cooling of the device to room temperature, the preservation of the changed appearance of all areas with heat-sensitive materials and the return of the original green color of the thermal paint were visually recorded.

[0232] Example 3.

[0233] We made a temperature indicator measuring 20*30 mm (600 cm) 2 ) with two MFCs and one BFC applied to the base as shown in Fig. 1. A heat-sensitive composition with a threshold temperature of 70 °C was used as MFC1, a heat-sensitive composition with a threshold temperature of 90 °C was used as MFCg, and a heat-sensitive composition with a threshold temperature of 50 °C was used as BFC. The BFC has a rectangular shape and a size of 16 * 10 mm (160 mm 2 ), which is 27% of the total surface area of ​​the temperature indicator for each BTE. Each MTE has a round shape with a diameter of 8 mm (50 mm 2 ). Thus, the total area of ​​all MFCs is 100 mm 2, which is smaller than the area of ​​the BFC. The MFCs are arranged in order of increasing threshold temperatures, forming a temperature-indicating scale. The BFC is located along all the MFCs. The minimum distance a between the BFC boundary and the boundaries of each MFC is the same and is 3 mm (Fig. Xd).

[0234] The temperature indicator was mounted on a heating element at room temperature, which was then heated in a controlled, uniform manner at a rate of 5°C / min to a temperature of 50°C with a specified accuracy. Heating was stopped, and the BTE activation was recorded by visually recording a white-to-green color transition. The surface was then sequentially uniformly heated to temperatures of 70°C and 90°C, and the activation of the corresponding device zones was recorded by visually recording a white-to-red color transition. The activation time and change in appearance for MTE1 was 3 seconds, for MTE2 – 1 second, and for BTE – 2 seconds. After the device had cooled to room temperature, the changed appearance of all zones containing heat-sensitive materials was visually recorded. All manufactured temperature indicators demonstrated high thermal monitoring information, noticeable activation, and easy interpretation of the results.In addition, the developed temperature indicators have high speed, accuracy, and irreversibility of response, which makes them preferable for use in the energy sector.

Claims

Invention formula 1. An irreversible temperature indicator, comprising a base on which temperature-sensitive elements (TE) are located, designed with the ability to irreversibly change their appearance upon reaching their corresponding threshold temperatures, among which the following can be distinguished: - at least two small temperature-sensitive elements (MTE1 and MTE2) having different threshold temperatures; - at least one large temperature-sensitive element (LTE); characterized in that the area of ​​the LTE is at least twice the area of ​​both MTE1 and MTE2.

2. A temperature indicator according to claim 1, in which the response speed of at least one TE, preferably a BTE, most preferably a BTE and an MTE, is no more than 5 seconds, preferably no more than 2 seconds.

3. A thermal indicator according to paragraph 1, in which the change in the appearance of the BTE is associated with the melting of a substance or group of substances included in the BTE.

4. A temperature indicator according to item 3, in which the BTE is located along at least MTE1 and MTE2, 5. A temperature indicator according to paragraph 3, in which the minimum distance from the boundary of the BTE to the boundary of each of the MTE differs by no more than 50%, preferably by no more than 20%.

6. A temperature indicator according to claim 1, in which at least three small temperature-sensitive elements (MTE1, MTEg, MTEz) can be distinguished, having different threshold temperatures, preferably located on the temperature indicator in order of increasing threshold temperatures.

7. A temperature indicator according to paragraph 1 or 3, in which the change in the appearance of at least one MFC is associated with the melting of a substance or group of substances included in the MFC.

8. A thermal indicator according to item 1, in which, in the initial state, the main area of ​​the MFC and BFC has the same, predominantly white, color.

9. A thermal indicator according to item 1, in which, when the MFC and BFC are activated, a white-to-black color transition is ensured.

10. A thermal indicator according to claim 1, in which the color of the BTE and at least one MTE differs after operation.

11. A temperature indicator according to claim 1, in which the MFCs form a temperature indicator scale, predominantly including temperatures selected from the list of 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C.

12. A temperature indicator according to paragraph 1, characterized in that it contains two BTEs having different threshold temperatures.

13. A temperature indicator according to claim 1, in which the areas of the MFC differ by no more than 20%, preferably by no more than 10%.

14. A temperature indicator according to item 1, in which the area of ​​the BTE is at least 25 mm 2 , preferably not less than 100 mm 2 .

15. A temperature indicator according to item 1, in which the BTE occupies at least 10%, preferably at least 20% of the total area of ​​the front surface of the temperature indicator.

16. A temperature indicator according to item 1, in which the total area of ​​all MFCs is less than the area of ​​BFCs.

17. A temperature indicator according to item 1, in which the shape of the BTE differs from the shape of the MTE.

18. The thermal indicator according to item 1, in which the threshold temperature of the BFC differs from the threshold temperatures of the MFC, in particular the threshold temperature of the BFC is higher than the threshold temperatures of all the MFC of the thermal indicator, or the threshold temperature of the BFC is lower than the threshold temperatures of all the MFC of the thermal indicator, or the threshold temperature of the BFC lies in the range between the threshold temperatures of the MFC of the thermal indicator.

19. A temperature indicator according to item 1, characterized in that it has at least one property selected from the group of properties (1) - (6): (1) in which at least one FC, preferably a BFC, includes a gas-filled hot-melt material (GFTM), preferably, the proportion of the gas phase in which is at least 10 vol.%.; (2) in which at least one TE contains an absorbent material (AM); (3) in which at least one TE contains support elements (SE); (4) at least one TE comprises at least one solid organic substance with a molecular weight of less than 2 kDa; (5) at least one TE changes appearance only in the region that was heated above the corresponding threshold temperature, while maintaining the original appearance of other regions of the TE whose temperature did not exceed the corresponding threshold temperature; (6) at least one TE comprises at least one solid organic substance containing a structural fragment C n H(2n+i), where n > 5, and is preferably selected from the group consisting of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 12; salts of fatty aliphatic acids containing structural fragments C nH(2n+i) with n > 5; alkanes containing at least 20 carbon atoms; dialkylphosphinic acids containing structural fragments C n H(2n+i) with n > 5; amides of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 5; anhydrides of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 10; fatty aliphatic alcohols containing structural fragments C n H(2n+i) with n > 14; fatty aliphatic amines containing structural fragments C n H(2n+i) with n > 17; nitriles of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 19.

20. A temperature indicator according to item 1, characterized in that it has at least one property selected from the group of properties (1) - (7): (1) made in the form of a sticker; (2) is elastic; (3) designed with the possibility of marking the elements of electrical equipment or color marking the phases; (4) the back side of the base contains an adhesive layer of permanent tack with adhesion of at least 10 N / 25 mm to stainless steel, measured by the FIN AT TM1 method after 24 hours; (5) base made of PVC, preferably cast PVC; (6) the TE and at least part of the base are covered with a protective layer, which is preferably made of PVC and is transparent to at least part of the visible light, at least in the area of ​​the TE; (7) the base is partially colored using a heat-sensitive material that reversibly changes its appearance when heated above the appropriate threshold temperature.

Images