Customizable semi-irreversible temperature exposure sensor using a thermal printer

Abstract

The invention relates to a customizable temperature exposure indicator and methods for manufacturing it. The temperature exposure indicator comprises a substrate, a printing region of the substrate forming a heat-sensitive support that is configured to darken when heated by a thermal print head, the darkening being permanent with respect to the subsequent cooling of the support;where at least one thermochromic memory composition is provided on an indication region of the substrate, the thermochromic composition is configured to have a high-temperature color state when heated above a high-temperature threshold, and to remain in the high-temperature color state until it is cooled below a low-temperature threshold; the thermochromic composition is configured to have a low-temperature color state when cooled below the low-temperature threshold and to maintain the low-temperature threshold until it is heated above the high-temperature threshold. Figure: 1;

Description

Title of the invention: Customizable semi-irreversible temperature exposure sensor using a thermal printer. Background

[0001] Many types of products are perishable under different environmental conditions. For example, products may be degraded or rendered unsafe or otherwise unusable by excessive cumulative exposure to heat over time or by exposure to maximum heat beyond a threshold that rapidly causes product deterioration, such as the denaturation of proteins in a biological product or the thawing of a frozen product. Other products may be negatively affected by being too cold, for example, by freezing or other undesirable physical changes caused by excessively low temperatures. Many types of indicators are used to show historical exposure to environmental conditions, for example, to low or excessively high temperatures, often in a visible way, such as by a color change in an indicator material.

[0002] Certain types of thermochromic materials. Often called thermochromic memory materials, they exhibit semi-irreversible color changes in response to temperature changes. These materials display a color-change hysteresis effect, transitioning to a high-temperature color state when heated above a high temperature threshold, and maintaining this color state when the material returns to a temperature below this threshold. The material then transitions to a low-temperature color state only when the temperature drops sufficiently below a low temperature threshold. The material then remains in the low-temperature color state until it returns to a temperature above the high temperature threshold.For example, the material may be light-colored in the low-temperature state and dark-colored in the high-temperature state, or vice versa; or the material may be transparent or invisible in the high-temperature state and colored or visible in the low-temperature state, or vice versa.

[0003] Since historical environmental exposure indicators and other types of temperature indicators are increasingly used, it is desirable to allow them to be added to product labels or packaging (or customized if already present) at the time of label and packaging manufacture, or even at the time a host product or its container is labeled.

[0004] A common approach to producing custom labels for packaging is the use of direct thermal printers, for example, the Zebra ZT600, Zebra ZT400, Zebra ZD600, and Zebra ZD400 series printers, available from Zebra Technologies Corp., or any other thermal printer. This disclosure describes semi-irreversible temperature exposure sensors that can be customized with such printers, as well as an associated manufacturing and customization process. Summary

[0005] The invention relates to customizable temperature exposure indicators and methods for manufacturing them. The temperature exposure indicator comprises a substrate, a printing region of the substrate forming a heat-sensitive support that is configured to darken when heated by a thermal print head, the darkening being permanent with respect to the subsequent cooling of the support;where at least one thermochromic memory composition is provided on an indication region of the substrate, the thermochromic composition is configured to have a high-temperature color state when heated above a high-temperature threshold, and to remain in the high-temperature color state until it is cooled below a low-temperature threshold; the thermochromic composition is configured to have a low-temperature color state when cooled below the low-temperature threshold and to maintain the low-temperature threshold until it is heated above the high-temperature threshold.

[0006] Aspects of the object described herein may be useful alone or in combination with one or more other aspects described herein. In one aspect of this disclosure, a temperature exposure indicator comprises a substrate, a printing region of the substrate forming a heat-sensitive support that is configured to darken when heated by a thermal print head, the darkening being permanent with respect to the subsequent cooling of the support.

[0007] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, at least one thermochromic memory composition is provided on an indication region of the substrate.

[0008] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the thermochromic composition is configured to have a high-temperature color state when heated above a high temperature threshold, and to remain in the high-temperature color state until it is cooled below a low temperature threshold.

[0009] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the thermochromic composition is configured to have a low-temperature color state when cooled below the low-temperature threshold and to maintain the low-temperature threshold until it is heated above the high-temperature threshold.

[0010] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the darkened portion of the support retains its dark appearance below the low temperature threshold.

[0011] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, a portion of the indication region is exposed to the high temperature threshold using a thermal printhead, while a remaining portion of the thermochromic composition is left in the low-temperature color state, thus providing a human-readable index in the indication region.

[0012] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the high temperature state of the thermochromic composition is invisible to the human eye, while the low temperature state is visible, or the high temperature state of the thermochromic composition is visible to the human eye, while the low temperature state is invisible.

[0013] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the visual characteristics of the thermochromic memory composition in the high-temperature color state may vary based on the hysteresis of the composition.

[0014] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the visual characteristics of the thermochromic memory composition in the low-temperature color state may vary based on the hysteresis of the composition.

[0015] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, a portion of the indication region is exposed to the low temperature threshold using a cooling agent, while a remaining portion of the thermochromic composition is left in the high temperature color state, thus providing a human-readable index in the indication region.

[0016] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the elevated temperature state of the thermochromic composition is invisible to the human eye, while The low temperature state is visible or the high temperature state of the thermochromic composition is visible to the human eye, while the low temperature state is invisible.

[0017] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the indication region and the printing region do not overlap.

[0018] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the indication region and the printing region overlap.

[0019] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the printing region occupies the entire surface of the substrate.

[0020] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the high temperature threshold temperature is in a range of about 5°C to about 100°C, about 20°C to about 80°C, about 30°C to about 70°C, about 40°C to about 60°C.

[0021] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the low temperature threshold temperature is in a range of about -30 °C to about 20 °C, about -15 °C to about 10 °C, about -5 °C to about 5 °C, about 0 °C to about 15 °C.

[0022] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the thermochromic composition comprises at least one of (i) a leuco dye; (ii) a liquid crystal; (iii) a wax; (iv) a microencapsulated dye; (v) an ester; (vi) an alkane; (vii) an organic polymer; (viii) an inorganic material.

[0023] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the substrate further comprises at least one of (i) paper; (ii) polyester; (iii) nylon; (iv) vinyl; (v) other synthetic polymer.

[0024] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the thermochromic composition is configured to provide multiple color states, visible to the human eye when the temperature exposure indicator is exposed to a threshold range.

[0025] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, multiple thermochromic compositions are provided on the substrate, each composition having a respective low-temperature threshold and low-temperature color state respective, or each composition has a respective high temperature threshold and a respective high temperature color state.

[0026] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the indication region covers at least a portion of a barcode symbol that is readable by an optical scanning device, the visual indication provided by the thermochromic composition affecting the appearance of the barcode, and the modified appearance of the indication region providing a different signal to the optical scanning device.

[0027] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the barcode symbol is printed and the indicator is placed in the elevated temperature state with the same printing operation.

[0028] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the substrate includes printed information identifying the indication region.

[0029] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, a method for creating a downward temperature indicator comprises receiving a substrate having a print area that darkens when heated by a thermal print head, the darkening being permanent with respect to subsequent cooling of the substrate, the substrate also having an indication area with a thermochromic memory composition provided on the substrate, the thermochromic composition being configured to have a high-temperature color state when heated above a high temperature threshold, and to remain in the high-temperature color state until it is cooled below a low temperature threshold,and a low-temperature color state when cooled below a low-temperature threshold, and to maintain the low-temperature threshold until heated above the high-temperature threshold, the substrate being provided with the thermochromic composition in the low-temperature color state.

[0030] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the printing of indices on the medium with a thermal printer in the printing area.

[0031] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the placement of a portion of the indication region in the high-temperature color state using the thermal printer.

[0032] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, leaving a second part of the indication region in the low-temperature color state when the substrate is printed, so that the combination of the first and second parts of the thermochromic composition forms a human-readable index indicating that the indicator has not been exposed to a temperature below the low-temperature threshold.

[0033] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the index changes or disappears when the indicator is exposed to a temperature below the low temperature threshold, and is configured to indicate that the indicator has been exposed to a temperature below the low temperature threshold.

[0034] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the high temperature threshold temperature is in a range of about 5°C to about 100°C, about 20°C to about 80°C, about 30°C to about 70°C, about 40°C to about 60°C.

[0035] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the low temperature threshold temperature is in a range of about -30 °C to about 20 °C, about -15 °C to about 10 °C, about -5 °C to about 5 °C, about 0 °C to about 20 °C.

[0036] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, at least a portion of the indication region is heated above the high temperature threshold, thereby placing the indication region in the high temperature state and simultaneously applying the thermochromic composition to the region of thermochromic material, the substrate passing through a thermal printer.

[0037] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, a method for creating a rising temperature indicator comprises receiving a substrate having a print area that darkens when heated by a thermal print head, the darkening being permanent with respect to subsequent cooling of the substrate, the substrate also having an indication area with a thermochromic memory composition provided on the substrate, the thermochromic composition being configured to have a low-temperature color state when cooled below a low-temperature threshold, and to remain in the low-temperature color state until heated above a high-temperature threshold,and a high-temperature color state when heated above a high temperature threshold, and to maintain the low threshold, temperature until it is cooled below the low temperature threshold, the substrate being provided with the thermochromic composition in the high temperature color state.

[0038] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the printing of indices on the medium with a thermal printer in the printing area.

[0039] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the placement of a portion of the indication region in the low-temperature color state using a cooling agent to form a human-readable index in the indication region.

[0040] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, leaving a second part of the indication region in the high-temperature color state when the support is cooled, so that the combination of the first and second parts of the thermochromic composition forms a human-readable index indicating that the indicator has not been exposed to a temperature above the high-temperature threshold.

[0041] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the index changes or disappears when the indicator is exposed to a temperature above the high temperature threshold, and is configured to indicate that the indicator has been exposed to a temperature above the high temperature threshold.

[0042] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the high temperature threshold temperature is in a range of about 5°C to about 100°C, about 20°C to about 80°C, about 30°C to about 70°C, about 40°C to about 60°C.

[0043] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the low temperature threshold temperature is in a range of about -30 °C to about 20 °C, about -15 °C to about 10 °C, about -5 °C to about 5 °C, about 0 °C to about 15 °C.

[0044] In another aspect of this disclosure, which may be used in combination with any other aspect or combination of aspects listed herein, the device is a printer.

[0045] These and other features are disclosed in more detail in the accompanying figures and the detailed description below. Brief description of the figures

[0046] Certain examples of embodiments of devices of the invention, and examples of procedures for manufacturing and using one or more examples of embodiments, are described in detail herein and by way of example, with reference to the accompanying drawings (which are not necessarily drawn to scale with respect to the internal or external structures illustrated) and in which similar reference numerals denote similar features in the different views, and in which:

[0047] [Fig. 1-2] Figure 1 illustrates a perspective view of a temperature exposure indicator prior to personalization, according to an example in this disclosure.

[0048] [Fig. 1-2] Figure 2 illustrates a perspective view of the temperature exposure indicator of Figure 1, after activation and where part of the indication region is in the elevated temperature state, according to an example in this disclosure.

[0049] [Fig. 3A-3B-3C] Figure 3A illustrates a perspective view of the layers of a temperature exposure indicator where the printing area and the indication area do not overlap, as an example in this disclosure.

[0050] [Fig. 3A-3B-3C] Figure 3B illustrates a perspective view of the layers of a temperature exposure indicator where the printing region and the indication region overlap and occupy the entire surface of the substrate, as an example in this disclosure.

[0051] [Fig. 3A-3B-3C] Figure 3C illustrates a perspective view of the layers of a temperature exposure indicator where the printing area and the indication area overlap and do not occupy the entire surface of the substrate, as an example in this disclosure.

[0052] [Fig. 4A-4B] Figure 4A illustrates an example of an indicator embodiment of downward temperature excursion, attached to a flask that has been maintained above a low temperature threshold as an example in this disclosure.

[0053] [Fig. 4A-4B] Figure 4B illustrates the indicator of Figure 4A, glued to a bottle, which subsequently underwent a downward temperature excursion, as an example in this disclosure.

[0054] [Fig. 5A-5B] Figure 5A illustrates an example of an excursion indicator of rising temperature, stuck to an object that has been kept below a high temperature threshold as an example in this disclosure.

[0055] [Fig. 5A-5B] Figure 5B illustrates the indicator of Figure 5A, glued to an object, which has subsequently underwent a high temperature excursion, as an example in this disclosure.

[0056] [Fig. 6A-6B] Figures 6A and 6B illustrate examples of alternative indicators using different indicators, as an example from this disclosure.

[0057] [Fig. 7A-7B] Figure 7A illustrates an example of an indicator where the printing region and the indication area overlap and occupy the entire surface of the substrate, as illustrated in an example in this disclosure.

[0058] [Fig. 7A-7B] Figure 7B illustrates another example of an indicator comprising a code bar-based where the printing area and the indication area overlap and occupy the entire surface of the substrate as an example in this disclosure.

[0059] [Fig.8] Fig.8 is a functional diagram illustrating a process for creating a indicator of rising or falling temperature, as an example in this disclosure.

[0060] Detailed description of examples of embodiments

[0061] This disclosure generally describes the use of semi-irreversible color-changing materials to produce several types of customizable labels with an indication of historical temperature exposure, some of which are suitable for use with thermal printers. Direct thermal printers can be used to customize the color state and appearance of the label. In other examples, alternative approaches to label customization may also be employed; for example, the use of a freezing spray may be employed as part of the customization process.Some of these indicators may be particularly suited to the manufacture of custom labels that are printed and / or personalized during the manufacture of a host product or during its packaging for distribution, or even at a later stage of its lifecycle or distribution chain.

[0062] In addition, techniques for printing activatable environmental exposure indicators, such as temperature exposure indicators, with thermal printer paper are described.

[0063] There is a need for an activatable medium that can be easily customized by product manufacturers or distributors, for example, product labeling at the point of manufacture or shipment, as well as for an indicator that is easy for an end user of the product to interpret when receiving a product with a label produced using the activatable medium. Some of the examples in this disclosure provide efficient on-demand label activation, which can occur simultaneously with the printing and / or time-stamping or recording of the labels. The disclosed approach can be used with various types of environmental exposure indicators that can be stored under a wide range of environmental conditions and detect a wide range of environmental conditions.

[0064] As used here, the term "low temperature threshold" refers to a temperature, usually below 0 °C, above which perishable products, such as food or a vaccine, must generally be These temperatures are maintained to prevent deterioration or to preserve effectiveness over extended periods. The threshold temperature may vary depending on the properties of the host product being monitored. A low-temperature excursion is an exposure of the product to temperatures below the low-temperature threshold, possibly for a short period, or possibly for a minimum duration, for example, long enough for the product or a component of the product to freeze or crystallize.

[0065] As used herein, the term "high temperature threshold" refers to a temperature at which, when a perishable product is exposed to a temperature above the threshold, it may damage or impair the product, for example, by causing deterioration or reduced product effectiveness. A high temperature excursion is an exposure of the product to temperatures above the high temperature threshold, possibly for a short period, or possibly for a minimum period. The high temperature threshold may vary depending on the nature of the host product and the degradation mechanism being monitored.For example, the mechanism in question may involve thawing (temperatures above a threshold of approximately 0 °C, although this varies depending on the nature of the host product and / or the melting point of one of its components), failure to maintain adequate refrigeration (temperatures above a threshold in the range of 6 °C to 15 °C, depending on the product and / or the refrigeration / storage protocol), or the product being allowed to overheat in warm ambient conditions (temperature thresholds of approximately 35 °C to approximately 60 °C. In some cases, the high temperature threshold may be higher than normal ambient conditions, for example, approximately 100 degrees C or even more).

[0066] As used herein, the term "thermal printhead" refers to a component of a thermal printing device that transfers heat and, optionally, applies pressure to a thermal printing substrate in response to an instruction from a control device, functionally connected to a thermal printer.

[0067] As used here, the term "thermochromic composition" refers to a composition or combination of compositions that have the property of changing color state in response to a change in temperature.

[0068] As used here, the term "cooling agent" is a substance or apparatus, for example a refrigerant used as a treatment, for example exposure to a certain amount of refrigerant which absorbs heat, so that the thermochromic composition in the indication region of the substrate is exposed to a temperature below the low temperature threshold, thus placing the indication region in a low temperature color state.

[0069] As used herein, the term "color state" refers to an observable color exhibiting a change in hue, darkness, color intensity, opacity, fluorescence or phosphorescence, or other observable optical properties of the indicator material. The change in color state may be detectable to the naked eye, or may occur in a manner that requires machine detection, for example, at wavelengths not visible to the naked eye.

[0070] As used here, the term "permanent" refers to a color state that is stable and intended to remain substantially unchanged with respect to subsequent cooling and / or heating of the substrate. However, subsequent changes to the permanent color state, such as discoloration, may occur due to conditions independent of the temperature-sensitive hysteresis properties of the composition. Since the visual appearance of the permanent color state changes over time, without necessarily depending on temperature, it is assumed that this will not occur during the intended lifetime of the device.

[0071] Downward-looking indicators

[0072] In this disclosure, examples of temperature-falling indicators include indicators that can be used to determine whether a perishable product has been exposed and / or maintained at a temperature below an acceptable temperature or temperature range.

[0073] To signal prior exposure to a temperature below a predetermined threshold, the indicators according to this disclosure may usefully have an observable appearance while the indicator is maintained within an acceptable temperature range above a low-temperature threshold, and a different observable appearance after the indicator has been exposed to a temperature below the low-temperature threshold. This observable change may include the appearance of an index indicating that the indicator has undergone a low-temperature excursion, the disappearance of an index indicating that the indicator has not been exposed to such a low temperature, or a change in color or other appearance of an index. This observable change may be provided by a thermochromic composition that changes color state in response to exposure to a temperature below the low-temperature threshold.

[0074] Upward indicators

[0075] In this disclosure, examples of rising temperatures include threshold temperature indicators that can be used to determine whether a perishable product has been kept within an acceptable temperature range or has been exposed to a temperature excursion exceeding a high temperature threshold.

[0076] To signal prior exposure to a temperature above a predetermined threshold, the indicators according to this disclosure may usefully have an observable appearance before exposure to a temperature equal to or above the threshold and a different observable appearance after the indicator's exposure. This observable change may be provided by the disappearance of an underlying thermochromic composition or index that was observable before the indicator was exposed to temperatures equal to or above the threshold temperature, the appearance of a warning or other indication that temperature exposure has occurred, or a change in the color or appearance of an index.

[0077] Indicator materials

[0078] In this disclosure, indicators of exposure to historical temperatures can be provided using semi-irreversible thermochromic compositions or thermochromic memory compositions. The selected thermochromic memory composition may exhibit hysteresis—the phenomenon in which the value of a physical property lags behind changes in the effect that drives it—between the low-temperature color state and the high-temperature color state of that system, for example, color density, although it is appreciated that any detectable change in color state may be used. These compositions are called thermochromic memory compositions because they exhibit a large hysteresis curve.

[0079] When the indicator material is placed in a state above a high temperature threshold, it enters a high-temperature color state, for example, by becoming light. It then remains light as long as the temperature is lowered below the threshold, until a low-temperature threshold is approached. At this point, the material transitions to a low-temperature color state, for example, by becoming dark. (It will be understood that other color state transitions may also be possible, depending on the material.) It then remains in the low-temperature color state, for example, dark, when the material is heated above the low-temperature threshold, until it begins to approach the high-temperature threshold. The potential hysteresis of the thermochromic memory composition can be advantageously exploited in state-change indicators, such as up- and down-phase indicators.Furthermore, given the potential for hysteresis, remaining in a particular color state does not necessarily mean remaining exactly the same color, due to the potential for variability in color density. Hysteresis is what advantageously ensures the desired "memory" or "irreversibility" functionality. However, the color change from light to dark or from dark to light is not abrupt, but rather gradual. cumulative, which advantageously offers the potential for a cumulative or thermometer-type functionality.

[0080] In this disclosure, the thermochromic memory composition may be one of (i) a leuco dye; (ii) a liquid crystal; (iii) a wax; (iv) a microencapsulated dye; (v) an ester; (vi) an alkane; (vii) an organic polymer; (viii) an inorganic material. In a further embodiment, the thermochromic composition may be one of a leuco dye, a microencapsulated leuco dye, microencapsulated leuco pigments (the basic components of thermochromic microcapsules include a dye, a developer, and a solvent), an SCC polymer, a water-based SCC polymer emulsion, a liquid crystal, inorganic materials, a diacetyl, an alkane, a wax, an ester, or combinations thereof.

[0081] In one embodiment, the thermochromic memory composition may be one of polyoxymethylenemelamine, maleate polymer, ODB-II, Green DCF, behenic acid methyl ester, resin, color modifier, bisphenol A derivative, leuco dye, and UV absorber. In one embodiment, the memory compositions may also be available in the form of pigment powder, water-based ink, or suspension matrices. For example, a water-based slurry having the components: melamine-formaldehyde resin, 3-diethylamino-6-methyl-7,2,4-xylidinofluorane, water, and aromatic ester may be used.

[0082] Activation - in general

[0083] A conventional printing technology for printing data forms or images, such as barcode symbols, is direct thermal printing. A direct thermal printer does not use a ribbon; rather, the printable substrate itself is the thermal substrate. The direct thermal substrate comprises a strip of material, for example, paper, polymers, or the like, which is impregnated or coated with a thermochromic material that changes color when exposed to sufficient heat. A common thermochromic material for such applications is a leuco dye. The substrate may be impregnated with a solid-state mixture of a dye and a suitable matrix, for example, a leuco fluorane dye and octadecylphosphonic acid.When the matrix is ​​heated above its melting point, the dye reacts with the acid, changes to its colored form, and the altered form is then retained in a metastable state as the matrix solidifies rapidly enough. This process is usually monochrome, but some two-color models exist, which can print both black and an additional color (often red) by applying heat at two different temperatures.

[0084] In the printing process, selected portions of the substrate change from a first chemical form, which is colorless, to a second chemical form, which is black or colored. The strip of direct thermal substrate is pressed against and moved in front of the thermal print head. The thermal print head receives data from a rendered bitmap and heats specific heating elements in the array of addressable heating elements according to the data.

[0085] To print labels or other documents, thermal printers can use a thermal printhead comprising a row of addressable heating elements to heat a thermal substrate. The elements are small compared to the image to be printed; for example, 8, 12, or 24 elements per mm are typical, and other resolutions are commercially available. This differs from thermal inkjet printers, which use addressable heating elements to heat ink or wax that is dripped or ejected onto a document or other printable substrate.

[0086] The heat from the heated elements causes the heat-sensitive substrate on the printing region to transition from colorless to colored. Furthermore, the heat from the heated elements can cause the thermochromic indicator compositions on the substrate's indicator regions to transition from a low-temperature color state to a high-temperature color state. Moreover, if different inks are applied with different response temperatures, this can enable selective imaging of specific printing regions. Printhead heating elements that are not heated generally do not cause a color transition. In some direct thermal substrates, a first zone of the substrate contains a thermochromic material that transitions from a first color to colorless, while a second zone of the printable substrate contains a thermochromic material that transitions from a second, different color to colorless.

[0087] Figure 1 illustrates a perspective view of the temperature exposure indicator before activation, according to an example in this disclosure. Optionally, the substrate may contain conventional elements of a thermal printing substrate, for example, by adding semi-irreversible indicator components to a conventional thermal printing substrate, as shown in Figure 1 in the upper right corner. In the example, the indicator is applied only in the corner, so that the printing substrate can still be printed using a conventional thermal printing process, either over the entire substrate or, as shown in Figure 1, in the portion of the substrate outside the upper right corner. Optionally, the substrate may have a predetermined pattern, with a conventional thermal printing substrate structure at certain predetermined locations, and with activatable environmental indicators at others. locations. Alternatively, conventional print support elements and environmental indicators may, in some cases, overlap.

[0088] With reference to Figure 1, the indicator 100a of Figure 1 may comprise a substrate 102, a printing region 104 of the substrate forming a heat-sensitive support configured to darken when heated by a thermal print head, the darkening being permanent with respect to subsequent cooling of the support.

[0089] The substrate 102 of the indicator 100 may also include an indication region 106 where at least one thermochromic memory composition is provided on an indication region 106 of the substrate 102. In one embodiment, the thermochromic memory composition may be applied according to the following techniques: screen printing, gravure printing, flexographic printing, inkjet printing and / or thermal transfer.

[0090] In the illustrated example, the thermochromic memory composition may be visible to the human eye when first applied to an indication region 106 of the substrate 102. It will be understood that the entire semi-irreversible indicator color state change cycle may not be visible to the human eye, but may instead occur entirely or partially in a manner not visible to the naked eye; for example, the color state changes in machine-readable wavelengths, such as UV, which are not visible to the naked eye. In one embodiment, a portion of the thermochromic composition in the indication region 106 is treated by the heat of the thermal printhead, and the treated portion becomes invisible, as illustrated in Figure 2, index 108.Conversely, other parts of the thermochromic composition in the indication region 106 remain visible, as applied to the substrate 102, because they have not undergone heat treatment. In one embodiment, the thermochromic memory composition located in the indication region 106 is configured to transition to a high-temperature color state when heated above a high temperature threshold, and to remain in the high-temperature color state until it is cooled below a low temperature threshold. Furthermore, the thermochromic memory composition located in the indication region 106 is configured to assume a low-temperature color state when cooled below the low temperature threshold and to maintain the low temperature threshold until it is heated above the high temperature threshold.During the initial preparation of the indicator, it may optionally be exposed to a temperature below the low temperature threshold of the indicator medium to ensure that it is in a low temperature state; this may be applied to the whole region. of indication, either selectively to only a part of the region, for example using a precise application of a freezing spray.

[0091] In one embodiment, the high temperature threshold temperature is in a range of about 5 °C to about 100 °C, about 20 °C to about 80 °C, about 30 °C to about 70 °C, about 40 °C to about 60 °C.

[0092] In one embodiment, the low temperature threshold temperature is in a range of about -30 °C to about 20 °C, about -15 °C to about 10 °C, about -5 °C to about 5 °C, about 0 °C to about 20 °C.

[0093] In one embodiment, the indication region 106 (or a portion thereof) may be provided in the low-temperature state, or may be cooled, for example, using a refrigerant, to bring it into the low-temperature state. Then, a portion of the indication region 106 may be exposed to the high-temperature threshold, for example, using a thermal printhead of a thermal printer, while a remaining portion of the thermochromic composition is left in the low-temperature color state. The portion of the indication region that is treated in this way may be selected to provide an index, for example, readable by humans and / or machines within the indication region. In one example embodiment, in the high-temperature state, the thermochromic composition may be invisible to the naked eye, while the low-temperature state is visible.It will be understood that, depending on the application, it may also be desirable for the high temperature state of the thermochromic composition to be visible to the human eye, while the low temperature state is invisible, or to use two distinct color states, for example, dark and light, or a change of hue, which clearly indicates to an observer what state the indicator is in.

[0094] In some examples, the substrate 102 may be one of (i) paper; (ii) polyester; (iii) nylon; (iv) vinyl; (v) other synthetic polymers. In an additional embodiment, the substrate 102 may be made of porous materials such as papers and films (for example, carbon fiber, Teslin synthetic paper, polyethylene (“PE”), polypropylene (“PP”), polytetrafluoroethylene (“PTFE”), polyester, polyethylene, polyolefin, polyimide, vinyl, acrylic film, polypropylene, nonwoven nylon, coated and uncoated direct thermal paper, printable polyethylene terephthalate (“PET”), oriented polypropylene (“OPP”), biaxially oriented polypropylene (“BOPP”). In an additional embodiment, the substrate 102 may include printed information identifying the indication region.

[0095] In some examples, the thermochromic memory composition applied to the indication region 106 is selected from the group consisting of (i) a leuco dye (ii) a liquid crystal; (iii) a wax; (iv) a microencapsulated dye; (v) of an ester; (vi) of an alkane; (vii) of an organic polymer; (viii) of an inorganic material. In a further embodiment, the thermochromic composition may be one of a leuco dye, a microencapsulated leuco dye, microencapsulated leuco pigments (the basic components of thermochromic microcapsules include a dye, a developer and a solvent), an SCC polymer, a water-based SCC polymer emulsion, a liquid crystal, inorganic materials, a diacetyl, an alkane, a wax, an ester or combinations thereof.

[0096] In one embodiment, the thermochromic memory composition may be one of polyoxymethylenemelamine, maleate polymer, ODB-II, Green DCF, behenic acid methyl ester, resin, color modifier, bisphenol A derivative, leuco dye, and UV absorber. In one embodiment, the thermochromic memory compositions may also be available in the form of pigment powder, water-based ink, or suspension matrices. For example, a water-based slurry having the components: melamine-formaldehyde resin, 3-diethylamino-6-methyl-7,2,4-xylidinofluorane, water, and aromatic ester may be used.

[0097] In one embodiment, the thermochromic composition provided in the indication region 106 is configured to provide multiple color states, visible to the human eye when the temperature exposure indicator is exposed to a range of thresholds. In a further embodiment, the multiple thermochromic compositions are provided on the substrate 102, each composition having a respective low-temperature threshold and a corresponding low-temperature color state, and each composition having a respective high-temperature threshold and a corresponding high-temperature color state.

[0098] In one embodiment, the thermochromic composition located in the indication region 106 is configured to have a high-temperature color state when heated above a high temperature threshold, and to remain in the high-temperature color state until it is cooled below a low temperature threshold. Furthermore, the thermochromic composition located in the indication region 106 is configured to have a low-temperature color state when cooled below the low temperature threshold and to maintain the low temperature threshold until it is heated above the high temperature threshold.

[0099] In one embodiment, as discussed previously, the supplied memory thermochromic composition or the selected memory thermochromic composition may exhibit hysteresis — the phenomenon in which the value of a physical property lags behind changes in the effect that The effect is—between the low-temperature color state and the high-temperature color state of this system, for example, the color density, although it is appreciated that any detectable change in color state can be used. These compositions are often called thermochromic memory because they exhibit a large hysteresis curve.

[0100] Figure 2 illustrates a perspective view of the temperature exposure indicator of Figure 1 after customization, where a portion of the indication region has been placed in the elevated temperature state, as an example in this disclosure. The indicator 100b can be placed in an elevated temperature state by selective exposure to heat while passing through a thermal printer. In some examples, the temperature threshold for activation can be from approximately 0 °C to 300 °C, from approximately 100 °C to 300 °C, and from approximately 200 °C to 300 °C. Activation can be achieved by applying a high temperature for a very short interval, for example, a few milliseconds. Typical thermal printheads have temperatures in the range of about 100°C to 300°C, which can be set down for some applications to about 100°C to 200°C.Any selected point on the substrate is typically exposed to the thermal print heads for a brief period of time, for example, a few milliseconds. The print area 104 of the substrate itself responds when it reaches a temperature within a range of approximately 0°C to 150°C, approximately 0°C to 50°C, approximately 50°C to 100°C, and approximately 100°C to 150°C.

[0101] In one embodiment, the entire substrate 102 is accessible to the thermal printer and its print head(s). In this example, everything outside the indication region 106 is the print region 104 with no print. Furthermore, the entire print region 104 is brought into a high-temperature color state by exposure to the thermal printer (for example, it changes from dark to light, revealing the star symbol).

[0102] In some examples, the thermal printer may include a processor, processor-coupled memory and a thermal printhead, e.g., a conventional thermal printer with software modifications, described elsewhere in this disclosure.

[0103] Referring to Figure 2, the indicator 100b was activated by passing it through a thermal printer. The substrate 102, which includes the heat-sensitive support of the printing region 104, was exposed to a high temperature for a short period, causing the heat-sensitive support to darken. The heat-sensitive support of the printing region 104 is configured so that the darkening is permanent regardless of the subsequent cooling of the indicator 100b.

[0104] The substrate 102 of the indicator 100b may also include an indicator region 106 where at least one thermochromic memory composition is provided on an indicator region 106 of the substrate 102. As illustrated, the thermochromic memory composition is visible to the human eye when it is arranged on an indicator region 106 of the substrate 102, although it would be appreciated if other approaches could be employed (for example, invisible wavelengths, or the reverse, or just a color change). In one embodiment, a portion of the thermochromic composition 108 in the indicator region 106 is treated by the heat of the thermal print head, and the treated portion becomes invisible. Conversely, other parts of the thermochromic composition in the indication region 106, namely 108, remain untreated and visible, as applied to the substrate 102 because they have not received heat treatment.In another embodiment, the entire region is first placed in the high-temperature state, then a portion of the indication region 106 is exposed to the low-temperature threshold using a cooling agent, and a remaining portion 108 of the thermochromic composition is left in the high-color-temperature state. The treated region can be selected to provide a human-readable index within the indication region 106; the index can be formed by the visible material, or in negative view by having only the background surrounding the visible index, or by using contrasting colors or other approaches. The human-readable index 108 can be any symbol or design chosen by the indicator user. For example, the human-readable index 108 can be a symbol, a shape, a word, a number, a message, a barcode, or any other conceivable design.

[0105] In certain embodiments, illustrated in more detail in Figures 3A to 3C, the indication region 106 and the printing region 104 may not overlap. In another embodiment, the indication region 106 and the printing region 106 may overlap. In yet another embodiment, the printing region 104 occupies the entire surface of the substrate 102 and the indication region 106 is contiguous with the printing region 104.

[0106] Figure 3A illustrates a perspective view of the layers of a temperature exposure indicator, shown in Figure 1, where the printing region and the indication region do not overlap, according to an example in this disclosure. With reference to Figure 3A, in this embodiment, the printing region 104 and the indication region 106 do not overlap and are not concentric. Here, the printing region 104 and the indication region 106 occupy different areas of the substrate 102. In one embodiment, the printing region 104 and the indication region 106 do not occupy the entire surface of the substrate 102. However, in an additional embodiment, the printing region 304 and the indication region 306 can occupy the entire surface of the substrate 102.

[0107] Figure 3B illustrates a perspective view of the layers of a temperature exposure indicator where the printing region and the indication region overlap and occupy the entire surface of the substrate, according to an example in this disclosure. With reference to Figure 3B, in this embodiment, the printing region 104' and the indication region 106' overlap and are concentric. However, here, the printing region 104' and the indication region 106' occupy the entire surface of the substrate 102.

[0108] Figure 3C illustrates a perspective view of the layers of a temperature exposure indicator similar to, but different from, indicator 100, where the printing area and the indication area overlap and do not occupy the entire surface of the substrate, as exemplified in this disclosure. With reference to Figure 3C, indicator 100a comprises a substrate 102 and, at the lowermost part of substrate 102, optionally includes an adhesive layer 110. The adhesive 110 may be any non-stick lining or adhesive backing that allows indicator 300a to be selectively attached to surfaces, for example, such as a label. The lowermost part 112 may be attached to any surface as required, for example, to containers for perishable goods, such as boxes or a vial for a biological product or vaccine.

[0109] In one embodiment, the indicator 100c also includes a printing area 104” and an indication area 106. In one embodiment, the printing area 104” and the indication area 106” overlap and are concentric. However, the printing area 104” and the indication area 106” do not occupy the entire surface of the substrate 102, thus allowing the remaining surface to be used for other non-thermal printing and non-indication purposes, such as the addition of applied adhesive labels or the like. In one embodiment, additional indicators using multiple thermochromic compositions can be placed on the available surface of the substrate 102.

[0110] Figure 4A illustrates a perspective view of a custom downward temperature excursion indicator of Figure 2, bonded to a flask, using a semi-irreversible temperature indicator composition. The indicator in Figure 4A was kept above a low-temperature threshold according to an example in this disclosure. One portion of 406 (in the inset illustration) was placed in the high-temperature state—where it has visible color—and the other portion of 406 (the lettering) was placed in the low-temperature state where it is not colored. This can be accomplished either by placing the entire indicator in the high-temperature state and then selectively cooling the lettering, or by placing The entire indicator is placed in a low-temperature state, and then a thermal printer or other selective heating device is used to bring the entire background to a high-temperature state. When the indicator falls below the low-temperature threshold, the index disappears, as the remaining portion of the indicator also returns to a low-temperature state. Referring to Figure 4A, indicator 400a is activated, and index 408 in indication region 406 is visible to the human eye. The portion of the thermochromic composition in indication region 406 that has been treated by the heat of the thermal printhead forms index 408. The printing region 404 of substrate 402 has darkened upon exposure to a thermal printhead; this darkening is permanent regardless of subsequent cooling of the substrate.In one embodiment, a portion of the indication region 406 is exposed to the low temperature threshold using a cooling agent, placing this portion of the indication region in a low-temperature color state. Meanwhile, a remaining portion 408 of the thermochromic composition is left in the high-temperature color state, thus providing a human-readable index 408 within the indication region 406. In one embodiment, the cooling agent may be a freezing spray or any other agent capable of reaching temperatures below the low temperature threshold. In one embodiment, the low temperature threshold temperature is in the range of approximately -30 °C to approximately 20 °C, approximately -15 °C to approximately 10 °C, approximately -5 °C to approximately 5 °C, and approximately 0 °C to approximately 15 °C.

[0111] Figure 4B illustrates an embodiment of Figure 4A, bonded to a bottle, which was subsequently subjected to a reduced temperature excursion, according to an example in this disclosure. With reference to Figure 4B, indicator 400b underwent a temperature excursion by being exposed to a temperature equal to or greater than a low temperature threshold. In one embodiment, the high temperature threshold temperature is in the range of approximately -30 °C to approximately 20 °C, approximately -15 °C to approximately 10 °C, approximately -5 °C to approximately 5 °C, and approximately 0 °C to approximately 15 °C. Therefore, since the thermochromic composition in the 406 indication region changes from a high-temperature color state to a low-temperature color state, the 408 "OK FOR USE" marking located in the 406 indication region is no longer visible to the human eye. This indicates that a reduced temperature excursion has occurred.

[0112] Figure 5A illustrates a perspective view of a customized up-temperature excursion indicator of Figure 2, bonded to an object using a semi-irreversible temperature-indicating composition. In one embodiment, the indicator of Figure 5A can be used to indicate whether an object has been exposed to a temperature greater than or equal to a sterilization temperature. According to an example in this disclosure, indicator 500a is activated, and index 508 within indication region 506 is visible to the human eye. The portion of the thermochromic composition in indication region 506 that has been heat-treated by the thermal printhead forms index 508. In one embodiment, a portion of indication region 506 has been exposed to the low-temperature threshold using a cooling agent, placing this portion of the indication region in a low-temperature color state. Meanwhile, a remaining portion 408 of the thermochromic composition is left in the high-temperature color state, thus providing a human-readable index 508 within indication region 406.Since the thermochromic composition in the indicator region 506 was not exposed to a temperature equal to or exceeding a high temperature threshold, the thermochromic composition remained in its low-temperature color state and did not transition to its high-temperature color state, thus providing a visible indicator to the human eye that the indicator was not exposed to a temperature equal to or exceeding a high temperature threshold, for example, the star pattern visible in the figure. In the illustrated embodiment, the given index 508 is visible to the human eye; a user of the object, with appropriate training, can determine that the object to which the indicator 500a is affixed has not been exposed to a high temperature (above a high temperature threshold) equal to the temperature required for sterilization to occur. (When the device has been heat-sterilized, the index disappears.)Therefore, the 508 index of "NOT STERILE" provides the user with an indication that the item is not sterile and therefore not in good condition for use. It should be understood that multiple types of indicators and other information may also be provided on the label.

[0113] Figure 5B illustrates an embodiment of Figure 5A, bonded to an object, which has subsequently undergone a high temperature excursion, according to an example in this disclosure. In one embodiment, when indicator 500b has undergone a temperature excursion, this means, for a high temperature exposure indicator, that the indicator has been exposed to a temperature above a high temperature threshold. When this occurs, index 508 of Figure 5A is no longer visible to the human eye in the indication region 506. In the illustrated embodiment, upon exposure to a temperature above the high temperature threshold, the thermochromic composition located in the indication region 506 transitions from a low-temperature visible color state to a high-temperature invisible color state.In one embodiment, the high temperature threshold is greater than or equal to a temperature required for sterilization. This makes the index 508 no longer invisible to the human eye, thus providing an indication that the indicator 500b affixed to the object has been exposed to a temperature. temperature equal to or above a high temperature threshold. In the illustrated embodiment, since the index 508 is no longer visible to the human eye, a user of the object, with appropriate training, notices that the index 508 is no longer visible and appreciates that the object to which the indicator 500a is affixed has been exposed to a temperature equal to or above a high temperature threshold and that the object is no longer usable.

[0114] Figures 6A and 6B illustrate additional embodiments of Figure 2 using different indices according to an example in this disclosure.

[0115] In the illustrated embodiment, the indicators 600a and 600b, the printing area 604, and the indication area 606 overlap and are concentric. However, the printing area 604 and the indication area 606 do not occupy the entire face of the substrate 602, thus allowing the remaining face area to be used for other purposes, such as labeling. In one embodiment, the index 608 can be any symbol or design chosen, for example, when the indicator is printed. For example, the index 608 can be a symbol, a shape, a word, a number, a message, a barcode, or any other conceivable design.

[0116] In one embodiment, again with reference to Figure 6A, a downward thaw indicator is disclosed. Heat from the thermal printhead causes the index 606 region to transition from a low-temperature color state to a high-temperature state, thus becoming invisible to the human eye. However, the thermal printhead selectively did not process the specific portion of the index 606 region, leaving the index 608 in the low-temperature state, thus providing the visible snowflake index. When the indicator 600a is exposed to a temperature equal to or greater than a high-temperature threshold, the index 608 will begin to transition from a low-temperature color state to a high-temperature state, thus becoming invisible to the human eye.This provides an indication to a trained user of the indicator that the products associated with indicator 600a have undergone a high temperature excursion and may not be suitable for use.

[0117] In one embodiment, as illustrated in Figure 6B, the indication region 606 covers at least a portion of a barcode symbol that is readable by an optical scanning device. The visual indication provided by the thermochromic composition located in the indication region 606 affects the appearance of the barcode, and the modified appearance of the indication region 606 can provide a different signal to the optical scanning device. Systems that combine color-changing temperature exposure indicators, such as the one described in Prusik U.S. Patent 10,318,781, can be provided using this approach, thus enabling a barcode reader or other device having a similar ability to read and interpret the semi-irreversible temperature exposure indicator.

[0118] Furthermore, in one embodiment, the barcode symbol is printed in the indication region 606 and the indication region 606 is placed in the elevated temperature state with the same printing operation.

[0119] Figures 7A and 7B illustrate embodiments of Figures 6A and 6B where the printing region and the indication region overlap and occupy the entire surface of the substrate according to an example in this disclosure.

[0120] Figure 8 is a working diagram illustrating an example of a method for creating a rising or falling temperature indicator according to an example in this disclosure. In block 802, a substrate is received that has a print area that darkens when heated by a thermal print head. For example, the substrate could be a conventional thermal printing substrate. In block 804, an indication area with a thermochromic memory composition can be provided on the substrate, either upon receipt or by applying the thermochromic memory material to the substrate. The thermochromic composition is configured to have a high-temperature color state when heated above a high temperature threshold and a low-temperature color state when cooled below a low temperature threshold, as illustrated in block 802.Next, the print area is darkened by heating with a thermal print head. This darkening is permanent regardless of the subsequent cooling of the substrate, as illustrated in block 806. Optionally, before this occurs, the entire indicator area can be cooled to ensure it is in the low-temperature color state. Alternatively, the entire area can be processed to place it in either the high-temperature or low-temperature color state, depending on the intended application of the indicator. In one embodiment, only a portion of the indicator area can be processed to place the indicator in a different temperature color state. Alternatively, the indicator can be received in a specific temperature color state, and only parts of the indicator are processed.

[0121] Still referring to [Fig. 8], at block 808, an index can be provided on the indication region using the thermal printer, by treatment with heat from the thermal print head. Alternatively, the treated part of the indication region becomes invisible. Conversely, other parts of the thermochromic composition in the indication region 106 remain visible, as they have not received heat treatment. If a downward temperature indicator is selected, a portion of the indication region is placed in the high-temperature color state using the thermal printer. as illustrated in block 808. In one embodiment, part of the indication region remains in the color state in which it was received. Optionally, if a rising temperature indicator is desired, part of the indication region is placed in the low-temperature color state using a cooling agent.

[0122] In one embodiment, as illustrated by block 812, the creation of a falling temperature indicator involves leaving a second part of the indication region in the low-temperature color state when the substrate is printed, such that the combination of the first and second parts of the thermochromic composition forms a human-readable index indicating that the indicator has not been exposed to a temperature below the low-temperature threshold. Furthermore, the index changes or disappears when the indicator is exposed to a temperature below the low-temperature threshold and is configured to indicate that the indicator has been exposed to a temperature below the low-temperature threshold.

[0123] In one embodiment, the high temperature threshold temperature is in the range of approximately 5 °C to approximately 100 °C, approximately 20 °C to approximately 80 °C, approximately 30 °C to approximately 70 °C, and approximately 40 °C to approximately 60 °C. Furthermore, in one embodiment, the low temperature threshold temperature is in the range of approximately -30 °C to approximately 20 °C, approximately -15 °C to approximately 10 °C, approximately -5 °C to approximately 5 °C, and approximately 0 °C to approximately 20 °C.

[0124] Optionally, the creation of a rising temperature indicator involves leaving a second part of the indication region in the high-temperature color state when the substrate is cooled, so that the combination of the first and second parts of the thermochromic composition forms a human-readable index indicating that the indicator has not been exposed to a temperature exceeding the high temperature threshold. Furthermore, the index changes or disappears when the indicator is exposed to a temperature exceeding the high temperature threshold and is configured to indicate that the indicator has been exposed to a temperature exceeding the high temperature threshold.

[0125] It should be understood that various changes and modifications to the examples of embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of this subject matter and without diminishing its anticipated advantages. It is therefore anticipated that such changes and modifications will be covered by the appended claims. Similarly, it should be considered that the features of the dependent claims can be incorporated into the systems, methods, and apparatus of each of the independent claims.

[0126] Many modifications and other embodiments of the invention presented herein will occur to the person skilled in the art to whom these inventions relate, once they have benefited from the lessons learned from the preceding descriptions and accompanying drawings. Therefore, it is understood that the inventions are not limited to the specific embodiments disclosed, and that the modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are used herein, they are used only in a generic and descriptive sense and not for the purpose of limitation.

Claims

Claims

1. A temperature exposure indicator, comprising: a substrate, a print region of the substrate forming a heat-sensitive direct thermal printing medium configured to darken when heated by a direct thermal printer printhead, the darkening being permanent with respect to subsequent cooling of the medium;at least one memory thermochromic composition provided on an indication region of the substrate, wherein the thermochromic composition is configured to have a high temperature color state when heated above a high temperature threshold, and to remain in the high temperature color state until cooled below a low temperature threshold, wherein the thermochromic composition is configured to have a low temperature color state when cooled below the low temperature threshold and to maintain the low temperature color state until heated above the high temperature threshold.;

2. The temperature exposure indicator of claim 1, wherein the darkened portion of the support maintains its dark appearance below the low temperature threshold.

3. The temperature exposure indicator of claim 1, wherein a portion of the indicating region is exposed to the high temperature threshold using a direct thermal print head, while a remaining portion of the thermochromic composition is left in the low temperature color state, thereby providing a human-readable indicia within the indicating region.

4. The temperature exposure indicator of claim 3, wherein the high temperature color state of the thermochromic composition is invisible to the human eye, while the low temperature color state is visible, or the high temperature color state of the thermochromic composition is visible to the human eye, while the low temperature color state is invisible.

5. The temperature exposure indicator of claim 1, wherein a portion of the indicating region is exposed to the low temperature threshold using a cooling agent, while a remaining portion of the thermochromic composition is left in the high temperature color state, thereby providing a human-readable indicia within the indicating region.

6. The temperature exposure indicator of claim 5, wherein the high temperature state of the thermochromic composition is invisible to the human eye, while the low temperature state is visible, or the high temperature color state of the thermochromic composition is visible to the human eye, while the low temperature color state is invisible.

7. The temperature exposure indicator of claim 1, wherein the visual characteristics of the memory thermochromic composition in the high temperature color state can vary based on the hysteresis of the composition.

8. The temperature exposure indicator of claim 1, wherein the visual characteristics of the memory thermochromic composition in the low temperature color state can vary based on the hysteresis of the composition.

9. The temperature exposure indicator of claim 1, wherein the indicating region and the printing region do not overlap.

10. The temperature exposure indicator of claim 1, wherein the indicating region and the printing region overlap.

11. A temperature exposure indicator according to claim 10, wherein the printing region occupies the entire face of the substrate.

12. The temperature exposure indicator of claim 1, wherein the indicating region is contiguous.

13. The temperature exposure indicator of claim 1, wherein the high temperature threshold temperature is in a range of about 5°C to about 100°C, about 20°C to about 80°C, about 30°C to about 70°C, about 40°C to about 60°C, or

14. c. The temperature exposure indicator of claim 1, wherein the low temperature threshold temperature is in a range from about -30°C to about 20°C, from about -15°C to about 10°C, from about -5°C to about 5°C, from about 0°C to about 15°C or

15. c. The temperature exposure indicator of claim 1, wherein the thermochromic composition comprises at least one of (i) a leuco dye (ii) a liquid crystal; (iii) a wax; (iv) a microencapsulated dye; (v) an ester; (vi) an alkane; (vii) an organic polymer; (viii) an inorganic material.

16. The temperature exposure indicator of claim 1, wherein the substrate further comprises at least one of (i) paper; (ii) polyester; (iii) nylon; (iv) vinyl; (v) other synthetic polymers

17. The temperature exposure indicator of claim 1, wherein the thermochromic composition is configured to provide multiple color states, visible to the human eye when the temperature exposure indicator is exposed to a threshold range.

18. The temperature exposure indicator of claim 1, wherein multiple thermochromic compositions are provided on the substrate, each composition having a respective low temperature threshold and a respective low temperature color state, or each composition has a respective high temperature threshold and a respective high temperature color state.

19. The temperature exposure indicator of claim 1, wherein the indication region covers at least a portion of a bar code symbol that is readable by an optical scanning device, wherein the visual indication provided by the thermochromic composition affects the appearance of the bar code, and wherein the altered appearance of the indication region provides a different signal to the optical scanning device.

20. The temperature exposure indicator of claim 19, wherein the bar code symbol is printed and the indicator is placed in the high temperature color state with the same printing operation.

21. The temperature exposure indicator of claim 1, wherein the substrate has printed information identifying the indication region.

22. A method of creating a falling temperature indicator, the method comprising: receiving a medium having a direct thermal print region that darkens when heated by a direct thermal printer printhead, the darkening being permanent with respect to subsequent cooling of the medium, the medium also having an indicator region with a memory thermochromic composition provided on the substrate, the thermochromic composition being configured to have a high temperature color state when heated above a high temperature threshold, and to remain in the high temperature color state until cooled below a low temperature threshold,and a low temperature color state when cooled below a low temperature threshold and to maintain the low temperature color state until heated above the high temperature threshold, the substrate being provided with the thermochromic composition in the low temperature color state, printing indicia on the medium with a direct thermal printer in the printing region; placing a portion of the indication region in the high temperature color state using the direct thermal printer.,

23. The method of claim 22, further comprising leaving a second portion of the indicator region in the low temperature color state when the medium is printed, such that the combination of the first and second portions of the thermochromic composition forms a human-readable indicia indicating that the indicator has not been exposed to a temperature below the low temperature threshold.

24. The method of claim 22, wherein the index changes or disappears when the indicator is exposed to a temperature below the low temperature threshold, and is configured to indicate that the indicator has been exposed to a temperature below the low temperature threshold.

25. The method of claim 22, wherein the high temperature threshold temperature is in a range of about 5°C to about 100 °C, from about 20 °C to about 80 °C, from about 30 °C to about 70 °C, from about 40 °C to about 60 °C.

26. The method of claim 22, wherein the low temperature threshold temperature is in a range of about -30°C to about 20°C, about -15°C to about 10°C, about -5°C to about 5°C, about 0°C to about 15°C.

27. ​​The method of claim 22, wherein at least a portion of the indicating region is heated above the high temperature threshold, thereby placing the indicating region in the high temperature state and simultaneously applying the thermochromic composition to the region of thermochromic material, the substrate passing through a direct thermal printer.

28. A method of creating a rising temperature indicator, the method comprising: receiving a medium having a direct thermal print region that darkens when heated by a direct thermal printer printhead, the darkening being permanent with respect to subsequent cooling of the medium, the medium also having an indicator region with a memory thermochromic composition provided on the substrate, the thermochromic composition being configured to have a low temperature color state when cooled below a low temperature threshold, and to remain in the low temperature color state until heated above a high temperature threshold,and a high temperature color state when heated above a high temperature threshold and to maintain the low temperature color state until cooled below the low temperature threshold, wherein the substrate is provided with the thermochromic composition in the high temperature color state, printing indicia on the medium with a direct thermal printer in the printing region; and placing a portion of the indication region in the low temperature color state using a cooling agent to form a human-readable indicia in the indication region.,

29. The method of claim 28, further comprising leaving a second portion of the indication region in the state of high temperature color when the medium is cooled, such that the combination of the first and second parts of the thermochromic composition forms a human-readable indicia indicating that the indicator has not been exposed to a temperature above the high temperature threshold.

30. The method of claim 28, wherein the index changes or disappears when the indicator is exposed to a temperature above the high temperature threshold, and is configured to indicate that the indicator has been exposed to a temperature above the high temperature threshold.

31. The method of claim 28, wherein the high temperature threshold temperature is in a range of about 5°C to about 100°C, about 20°C to about 80°C, about 30°C to about 70°C, about 40°C to about 60°C.

32. The method of claim 28, wherein the low temperature threshold temperature is in a range of about -30°C to about 20°C, about -15°C to about 10°C, about -5°C to about 5°C, about 0°C to about 15°C.

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