Multi-layer colorimetric indicator

Abstract

The device 5 comprises a first layer 20 comprising a colorimetric indicator; and a second layer 30 disposed on at least a portion 22 of the first layer 20, at least a portion of the second layer 30 being configured to block and / or absorb radiation to which the indicator is sensitive or reactive and being configured to be substantially transparent to visible light.

Description

Technical Field

[0001] This invention relates to colorimetric indicators. Specifically, but not exclusively, this invention relates to an apparatus for improving the visualization of color changes in a colorimetric indicator. Background Technology

[0002] Many products exist that provide a visual indication (through color change) of exposure to a certain amount of a specific compound or radiation. Such products typically include one or more colorimetric indicators. For example, colorimetric indicators rely on the optical properties of reactive dyes or inks. These dyes can exist in at least two different chemical states, each form absorbing light within a specific wavelength range. When this reactive dye, existing in the first form, is exposed to a given substance, it reacts with the substance via a reversible chemical reaction, transforming into the second form of dye. Because the second form of dye absorbs light at a different wavelength, the chemical reaction provides a color change visible to the observer. Colorimetric indicators can be configured to display reversible or irreversible color changes, depending on their intended use and the chemical substance, radiation, or stimulus that causes the indicator's color change. An example of a colorimetric indicator responsive to ultraviolet radiation (UVR) is disclosed in WO 2010 / 070290 (Mills et al.), the contents of which are incorporated herein by reference in their entirety.

[0003] Exposing a surface to a given type of radiation may be desired or intentional, or it may be undesirable or unintentional.

[0004] For example, while skin exposure to direct sunlight may be desirable and beneficial to some extent, excessive exposure to ultraviolet radiation is a recognized health hazard. There are certain products, such as those marketed under the name Smartsun... TM Stickers or wristbands sold that include a colorimetric indicator that displays a color change after exposure to a certain type and / or amount of UV radiation. This provides the user with a visual indication of the relationship to exposure to a predetermined amount of UV radiation.

[0005] In another example involving sterilization and disinfection, the product includes a colorimetric indicator that displays a color change after exposure to a certain amount of UVC radiation. This provides the user with a visual indication of the association with UVC radiation exposure. UVC irradiation is a known technique for disinfecting and sterilizing surfaces, such as in medical settings or the food industry.

[0006] Other products rely on color indicators, which exhibit color changes upon exposure to specific compounds or chemicals (such as carbon dioxide, oxygen, ammonia, etc.). These are useful, for example, in the food industry.

[0007] While products incorporating colorimetric indicators provide a useful indication of potential exposure to a given type of radiation, irritant, or chemical, the challenge with these systems is that the visual assessment of a given color change can be difficult and subject to interpretation, potentially leading to counterproductive or even dangerous decisions when subsequent decisions are based on such assessments. Typically, users only notice a color change in the indicator when a significant color change occurs. For UV indicators, this can correspond to a relatively high exposure dose. Specifically, if the indicator is used in a hospital setting, a relatively low exposure dose is visually detected on the indicator (e.g., at 6 mJ / cm²). 2 (or within a smaller scope) may be useful.

[0008] Some colorimetric indicators include one or more reference portions designed to indicate the target color of the indicator after exposure to a predetermined dose of radiation. Examples of such systems include US 2017 / 0191866 A1 (Balooch et al.), EP0487792A1 (Pugh et al.), and US5117116A (Bannard et al.), which disclose colorimetric indicator systems including one or more reference regions corresponding to the respective colors of a radiation-sensitive indicator when exposed to different predetermined amounts of radiation.

[0009] These systems have several drawbacks. For example, the reference area is colored or printed with a non-reactive composition different from the indicator itself, so it cannot represent a perfect color match with the indicator color, whether before or after exposure to a predetermined dose of radiation. Furthermore, the color of the reference ink may vary from batch to batch and / or may fade or change due to aging or exposure to environmental factors (e.g., light, temperature, humidity, etc.). Therefore, the expected color match between the reference portion and the indicator in a given state (e.g., unexposed or after exposure) lacks reliability.

[0010] Other documents, including US2020149960A1 (Foller et al.) and US9658101B1 (Levine et al.), disclose indicators with a typically multi-layered arrangement, which do not include any reference portion.

[0011] The purpose of this invention is to solve and / or mitigate one or more problems associated with the prior art. Summary of the Invention

[0012] According to a first aspect, an apparatus is provided, comprising:

[0013] Including the first layer of the colorimetric indicator; and

[0014] A second layer is disposed on at least a portion of the first layer, at least a portion of the second layer being configured to block and / or absorb radiation to which the indicator is sensitive or responsive, and being configured to be substantially transparent to visible light.

[0015] The portion of the second layer that is configured to block and / or absorb radiation to which the indicator is sensitive and that is configured to be substantially transparent to visible light may be referred to as the active portion.

[0016] The second layer may include at least one inactive portion. The inactive portion may not block and / or may not absorb radiation to which the indicator is sensitive. The inactive portion may be substantially transparent to visible light and / or to radiation to which the indicator is sensitive. Typically, the inactive portion may be substantially transparent to both visible light and radiation to which the indicator is sensitive.

[0017] The active portion of the second layer can be transparent to visible light. Advantageously, the active portion of the second layer can maintain the indicator's color under visible light. With this arrangement, the presence of the second layer does not affect the color of the indicator observed and / or perceived by the user viewing the indicator through the second layer and / or the first layer. In other words, whether the indicator is seen directly through the first layer or indirectly through the active portion of the second layer and / or the first layer, the color of the indicator perceived by the user can be substantially the same.

[0018] The second layer, such as its active portion, can be transparent to radiation in the range of approximately 400-800 nm (e.g., approximately 400-740 nm).

[0019] Advantageously, the presence of an active portion configured to block and / or absorb radiation to which the indicator is sensitive and configured to be substantially transparent to visible light can provide a reliable reference portion in the device. Specifically, the area of ​​the device including the active portion can represent or define the reference portion. Because the active portion is configured to block and / or absorb radiation to which the indicator is sensitive, the indicator will not change color in the area covered by the active portion when exposed to radiation that would normally cause a color change.

[0020] The radiation to which the indicator is sensitive will be referred to as "trigger radiation" in this article.

[0021] The indicator and / or the first layer may include a first part and a second part. The first part may not be covered by the second layer, or it may be covered by the inactive part of the second layer. The second part may be covered by the active part of the second layer.

[0022] Advantageously, the first and second portions of the indicator can display the same color before exposure to trigger radiation. Therefore, the reference portion can provide a perfect color match with adjacent portions of the device, such as a perfect color match with a portion of the indicator in which the indicator is not covered by the active portion of the second layer, regardless of any potential batch variations or any minor changes in the indicator's original (unexposed) color. In contrast, prior art reference portions cannot provide a perfect match because they typically involve the use of non-reactive dyes, pigments, or inks different from those used for the indicator itself.

[0023] Advantageously, because the colors of the first and second portions of the indicator in the first layer are perfectly matched before exposure to trigger radiation, the device of this application allows the user to detect a visible color change after exposure to a low level or dose of trigger radiation, such as after exposure to a level or dose of trigger radiation below the minimum dose at which the user would normally be able to detect a color change in the indicator.

[0024] Advantageously, when exposed to approximately 8 mJ / cm 2 For example, approximately 6 mJ / cm 2 For example, approximately 5 mJ / cm 2 After the trigger radiation dose is applied, the user can detect a color change in the indicator (e.g., in its first section).

[0025] The active portion of the second layer may include a radiation-absorbing component configured to absorb trigger radiation, such as a radiation absorber. It should be understood that the radiation absorber selected in the active portion may depend on the specific colorimetric indicator used in the first layer. For example, the radiation absorber may be a UV radiation absorber, such as a UVC absorber. The radiation absorber may include one or more compounds selected from benzophenone, hydroxybenzophenone, hydroxyphenylbenzotriazole, phenolic benzotriazole, benzotriazole, hydroxyphenyltriazine, and oxaloyl aniline. The radiation absorber may include benzophenone and / or phenolic benzotriazole.

[0026] The second layer may include or may be a coating. Typically, when the second layer includes a coating, the second layer may be disposed only on a portion of the first layer (e.g., the second portion). The second layer may be an active portion, may define an active portion, or may overlap with an active portion. Therefore, the first portion of the first layer may not be covered by the coating, and the second portion of the first layer may be covered by the coating.

[0027] The coating may include or may be provided in the form of a varnish.

[0028] Typically, the first layer, such as the indicator layer, can be a solvent-based composition.

[0029] The second layer, such as a coating or varnish, can be a solvent-based coating composition. With this arrangement, the coating can have improved compatibility with the first layer (e.g., with the indicator layer).

[0030] The coating may include polymer adhesives and solvents.

[0031] Radiation-absorbing components can be part of the coating, for example, they can form part of the adhesive.

[0032] Radiation-absorbing components can be radiation-absorbing additives. Therefore, the coating can include polymer binders, solvents, and radiation absorbers. Radiation absorbers can include one or more compounds selected from benzophenone, hydroxybenzophenone, hydroxyphenylbenzotriazole, phenolic benzotriazoles, benzotriazoles, hydroxyphenyltriazine, and oxaloyl aniline. Radiation absorbers can include benzophenone and / or phenolic benzotriazoles.

[0033] The coating may include a radiation absorber configured to absorb triggered radiation. It should be understood that the radiation absorber selected in the coating may depend on the specific colorimetric indicator used in the first layer.

[0034] In some embodiments, the coating may include or may be a composition sold by Fujifilm Corporation as APR VA401 or as Fujifilm Sericol PY433 EL overprint, or by Marabu as... The composition is sold by Mold MPC910. The second layer may have a relatively high viscosity. Advantageously, the inventors have surprisingly discovered that higher viscosity increases the ability of the second layer to block and / or absorb radiation (e.g., UV). This allows the second layer to block and / or absorb radiation without the need for radiation absorber additives.

[0035] The second layer may include or may be a laminate. The second layer may be laminated on the first layer, for example, on the indicator layer. The second layer may be a self-supporting layer, such as a membrane.

[0036] An adhesive may be disposed between the second layer and the first layer. The second layer may include an adhesive layer and may be configured to attach to the first layer.

[0037] The second layer may be adhesive-free. The second layer may be configured to be laminated (e.g., thermal lamination or pressure lamination) on the first layer.

[0038] Typically, when the second layer includes a self-supporting layer and / or a laminated layer, the second layer may be disposed on only a portion of the first layer (e.g., the second portion), or may be disposed on at least a portion of the first portion and both the second portion of the first layer.

[0039] When the second (self-supporting) layer is only disposed on a portion of the first layer (e.g., the second portion), the second layer may define the active portion or may overlap with the active portion. Therefore, the first portion of the first layer may not be covered by the second (self-supporting) layer.

[0040] When a second (self-supporting) layer is disposed on at least a portion of the first portion and the second portion of the first layer, the second layer may include the first portion and the second portion.

[0041] The first portion of the second (self-supporting) layer may include or may define the inactive portion of the second layer. The first portion or inactive portion may be substantially transparent to visible light and radiation to which an indicator responds (e.g., trigger radiation).

[0042] The second portion of the second (self-supporting) layer may include or may define the active portion of the second layer. The second portion or active portion may be substantially transparent to visible light, but may be configured to block and / or absorb radiation to which an indicator responds, such as trigger radiation.

[0043] The second (self-supporting) layer may include a polymer. Typically, the coating may include a polymer binder and a radiation absorber.

[0044] The active portion of the second (self-supporting) layer may include a radiation absorber configured to absorb triggered radiation. It should be understood that the radiation absorber selected in the active portion may depend on the specific colorimetric indicator used in the first layer.

[0045] The first layer, such as the indicator layer, can be disposed on the substrate.

[0046] The substrate may include a self-supporting layer. The substrate may include films, sheets, etc.

[0047] The first layer can be disposed on the substrate. In use, the substrate can be disposed on the lower side of the device.

[0048] The second layer can be disposed on the first layer or a portion thereof. In use, the second layer can be disposed on the upper side of the device.

[0049] The device can be or can be provided as an item, such as a wearable item like a wristband, patch, sticker, etc.

[0050] The first layer may have a thickness higher than a predetermined level. The first layer may have a thickness of at least 0.1 mm. The inventors have discovered, surprisingly, that when the first layer has a thickness greater than about 0.1 mm, the presence of the second layer may not be easily detected visually before exposure to triggering radiation.

[0051] A colorimetric indicator may be capable of exhibiting a color change in response to exposure to UV radiation (e.g., UVA, UVB, and / or UVC radiation). The triggering radiation may be any group consisting of UVA, UVB, UVC, or combinations thereof. A colorimetric indicator may be or may include a UV indicator. A colorimetric indicator may be substantially as described in WO 2010 / 070290 (Mills et al.), the contents of which are incorporated herein by reference.

[0052] In this embodiment, the colorimetric indicator may be a UVA and / or UVB indicator. The triggering radiation may be UVA and / or UVB. The triggering radiation may be in the range of 280-400 nm. In this case, the device may be a sunburn indicator, which may be provided in the form of a wearable item, such as a band, patch, sticker, tape, etc.

[0053] In another embodiment, the colorimetric indicator may be a UVC indicator. The triggering radiation may be UVC. The triggering radiation may be in the range of 100-280 nm. In this case, the device may be a disinfection indicator and / or a sterilization indicator.

[0054] A colorimetric indicator may have a first state associated with a first color. The first state and / or the first color may be associated with no color change. For example, the first state and / or the first color may be associated with the indicator not being exposed to trigger radiation or the indicator being exposed to levels below a predetermined and / or threshold activation level (e.g., below 0.1 mJ / cm²). 2 For example, below 0.5 mJ / cm 2 For example, below 1 mJ / cm 2 This is associated with the triggered radiation.

[0055] The colorimetric indicator may have a second state associated with a second color. The second state and / or the second color may be associated with a complete or final color change. For example, the second state and / or the second color may be associated with the indicator being fully exposed to trigger radiation or the indicator being exposed to an activation level above a predetermined and / or upper limit (e.g., above 0.1 mJ / cm²). 2 For example, below 0.5 mJ / cm 2 For example, below 1 mJ / cm 2 This is associated with the triggered radiation.

[0056] The colorimetric indicator may have one or more intermediate states, each associated with a corresponding intermediate color. The one or more intermediate states and / or one or more intermediate colors may be or may include one or more states and / or colors between a first state and / or a first color and a second state and / or a second color. Each intermediate state and / or intermediate color may be associated with exposure to a predetermined level or dose of triggered radiation.

[0057] Each of the first state and / or first color, intermediate state and / or intermediate color, and second state and / or second color may correspond to or be associated with trigger radiation exposure at a predetermined level or dose.

[0058] The device may also include at least one additional reference color area. The at least one additional reference color area may correspond to a first color, a second color, and any intermediate color. With this arrangement, in use, a user or observer can obtain further visual evaluation by comparing the color of the indicator or the first layer (e.g., its first area) with the color of at least one additional reference color area. In an embodiment, the at least one additional reference color area may be configured to substantially match the color of the indicator in the second (active) portion. With this arrangement, the additional reference color area can provide an additional reference area besides the reference area defined by the second portion of the device and / or the active portion of the second layer. Attached Figure Description

[0059] Embodiments of this disclosure will now be given by way of example only and with reference to the accompanying drawings, which are:

[0060] Figure 1 This is a schematic diagram of the apparatus according to the first embodiment;

[0061] Figure 2 This is a schematic diagram of the device according to the second embodiment;

[0062] Figure 3 This is a schematic diagram of the apparatus according to the third embodiment;

[0063] Figure 4 yes Figure 1 Images of the device when exposed to different doses of irradiation. Detailed Implementation

[0064] refer to Figure 1 The diagram shows an indicator device generally represented by 5 according to the first embodiment.

[0065] The device 5 includes a substrate 10. In this embodiment, the substrate 10 is in the form of a film.

[0066] The device has a first layer 20 including a colorimetric indicator. In use, the first layer 20 is disposed on the upper side of the substrate 10, that is, on the side of the substrate configured to face the radiation source.

[0067] The first portion 21 of the first layer 20 (the peripheral portion 21 in this embodiment) is exposed to the environment on its upper side (i.e., on the side opposite to the substrate 10). Therefore, when the indicator in the first layer 20 is exposed to trigger radiation, this will cause the indicator of the first layer to change color.

[0068] The second portion 22 of the first layer 20 (the central portion 22 in this embodiment) is covered by the second layer 30. In this embodiment, the second layer 30 is a coating or varnish.

[0069] The coating 30 includes a radiation absorber that blocks or absorbs triggering radiation to which an indicator responds. In this embodiment, the radiation absorber is a phenolic benzotriazole.

[0070] The second layer 30 is substantially transparent to visible light, allowing users to observe the second part 22 of the first layer through the second layer.

[0071] In use, before the device 5 is exposed to the irradiation source 40, the colors of the first portion 21 without coating 30 and the second portion 22 covered by coating 30 in the first layer 20 are perfectly matched to the observer because the entire first layer 20 includes the same indicator.

[0072] After the device is exposed to radiation 40, the indicator not covered by coating 30 reacts in the first portion 21 of the first layer 20 and thus changes color. Therefore, the second portion 22 serves as a reference portion and allows the color change in the first portion 21 to be detected after exposure to low levels or doses of trigger radiation 40 (e.g., after exposure to levels or doses of trigger radiation 40 below the minimum dose that a user would normally be able to detect in the indicator color change).

[0073] refer to Figure 2 The diagram illustrates an indicator device, generally designated 105, according to a second embodiment. The indicator device 105 is generally similar to... Figure 1 The same part of the indicator device 5 is represented by the same number incremented "100".

[0074] In this embodiment, the second layer 130 is a self-supporting layer laminated on top of the first layer 120. The second layer has a first outer portion 131 and a second inner portion 132.

[0075] The first portion 131 of the second layer 130 defines the inactive portion of the second layer 130 and is substantially transparent to visible light and to the trigger radiation 140 to which the indicator in the first layer 120 is sensitive. Therefore, the first portion does not affect how the first layer 120 responds to the trigger radiation 140.

[0076] The second portion 132 of the second layer 130 defines the active portion of the second layer 130. The active portion 132 is substantially transparent to visible light, but includes a radiation absorber that absorbs or blocks the trigger radiation 140 to which the indicator is sensitive.

[0077] In use, before the device 105 is exposed to the irradiation source 140, the color of the first portion 121 in the first layer 120 covered by the inactive portion 131 of the second layer 130 and the color of the second portion 122 covered by the active portion 132 or the second layer 130 are perfectly matched to the observer because the entire first layer 120 includes the same indicator.

[0078] After device 105 is exposed to radiation 140, the indicator covered by the inactive portion 131 of the second layer 130 reacts in the first portion 121 of the first layer 120 and thus changes color. Therefore, the second portion 122 serves as a reference portion and allows detection of the color change in the first portion 121 after exposure to low levels or doses of trigger radiation 140 (e.g., after exposure to levels or doses of trigger radiation 140 below the minimum dose that a user would typically be able to detect in the indicator).

[0079] Figure 3 A third embodiment of the indicator device, generally designated 205, is shown. The indicator device 205 is generally similar to... Figure 2 The same part of the indicator device 105 is represented by the same number incremented "100".

[0080] In this embodiment, the second layer 230 is also a self-supporting layer laminated on top of the first layer 220. However, in this embodiment, the second layer 230 has a first outer portion 231 that covers only a portion of the first layer 220.

[0081] Therefore, the first portion 221 of the first layer 220 has a covered area 221a and an uncovered area 221b covered by the inactive portion 231 of the second layer. Because the inactive portion 231 of the second layer 230 is substantially transparent to visible light and to the trigger radiation 240 to which the indicator in the first layer 220 is sensitive, the first portion 221 of the first layer 220 will respond to the irradiation 240 in the same manner in both its covered area 221a and its uncovered area 221b.

[0082] refer to Figure 4 This shows, as Figure 1 The image shows the device 305 as described in the general description, exposed to different doses of irradiation. In this embodiment, the device 305 includes a UVC indicator in its first layer 320, and the central portion of the first layer is covered by a coating 330 comprising a UVC radiation absorber. In this embodiment, the UVC indicator contains thymol blue as a pH indicator, NaOH, diphenyliodine chloride (DPIC) as a photoacid-producing agent, and polyvinyl butyral as a binder.

[0083] The coating is Fujifilm APR VA401.

[0084] In this embodiment, each of the five devices 305a, 305b, 305c, 305d, and 305e is exposed to corresponding doses of UVC radiation, namely 2, 4, 6, 8, and 10 mJ / cm², respectively. 2 .

[0085] As can be seen from samples 305a and 305b, 2 or 4 mJ / cm 2 The irradiation dose was insufficient to trigger visible changes in the first (indicator) layers 320a and 320b, respectively.

[0086] However, sample 305c showed that when exposed to 6 mJ / cm³, 2 At a UVC dose, a visible color change can be detected in the first portion of the first layer 320c. A second layer 330c, containing a UVC absorber, is coated with the central portion of the first layer 320c and thus serves as a reference portion for maintaining the color of the indicator in the unexposed state. As a result, the color change in the first layer 320c in the portion adjacent to the second (central) layer 330c is more easily detected by the observer, who might otherwise be unable to reliably and confidently detect a UVC dose of 6 mJ / cm². 2 The color changed after exposure.

[0087] Samples 305d and 305e were confirmed to have been exposed to 8 mJ / cm³, respectively. 2 and 10mJ / cm 2 After that, the colors of the indicators on the first layer, 320d and 320e, changed even more drastically.

[0088] It should be understood that the described embodiments are not intended to limit the scope of the invention, and that variations of the described examples may be used to implement the invention.

Claims

1. A device for improving visualization of a colour change in a colorimetric indicator, comprising: a first layer comprising the colorimetric indicator, wherein the colorimetric indicator comprises a UV indicator; and a second layer disposed on at least a portion of the first layer, wherein the first layer comprises a first portion and a second portion adjacent to the first portion, wherein at least a portion of the second layer defines an active portion configured to block and / or absorb radiation to which the indicator is sensitive or reactive thereby preventing a colour change of the second portion of the first layer upon exposure to the radiation, the active portion being configured to be substantially transparent to visible light, wherein the second portion of the first layer is covered by the active portion of the second layer; and wherein the first portion of the first layer is not covered by the second layer or is covered by a non-active portion of the second layer, the non-active portion being substantially transparent to visible light and radiation to which the indicator is sensitive.

2. The device of claim 1, wherein the second layer comprises at least one non-active portion, wherein the at least one non-active portion is substantially transparent to both visible light and radiation to which the indicator is sensitive.

3. The device of any preceding claim, wherein the active portion of the second layer is transparent to radiation in the range 400-800 nm.

4. The device of any preceding claim, wherein the active portion of the second layer comprises a radiation absorber configured to absorb the radiation.

5. The device of any preceding claim, wherein the second layer comprises a coating.

6. The device of claim 5, wherein the second layer is disposed only on the second portion of the first layer.

7. The device of claim 5 or claim 6, wherein the coating is provided in the form of a varnish.

8. The device of any preceding claim, wherein the first layer comprises a solvent-based composition.

9. The device of any preceding claim, wherein the second layer comprises a solvent-based composition.

10. The device of any one of claims 1 to 4, wherein the second layer comprises a self-supporting layer.

11. The device of any one of claims 1 to 4, wherein the second layer comprises a film.

12. The device of claim 10, wherein the second layer is laminated to the first layer.

13. The device of claim 10, wherein an adhesive is disposed between the second layer and the first layer.

14. The device of any one of claims 10 to 13, wherein the second layer is disposed only on the second portion of the first layer and the second layer defines the active portion.

15. The device of any one of claims 10 to 13, wherein the second layer is disposed on both at least a portion of the first portion and the second portion of the first layer and the second layer comprises corresponding first and second portions.

16. An apparatus according to claim 15, wherein the first portion of the second layer defines the non-active portion, and wherein the second portion of the second layer defines the active portion.

17. An apparatus according to any preceding claim, wherein the first layer has a thickness of at least 0.1 mm.

18. An apparatus according to any preceding claim, wherein the apparatus is provided as a wearable article.

19. An apparatus according to any preceding claim, wherein the colorimetric indicator is a UVA and / or UVB indicator.

20. An apparatus according to any of claims 1 to 18, wherein the colorimetric indicator is a UVC indicator.

21. An apparatus according to any preceding claim, wherein the apparatus further comprises at least one additional reference color region.

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