WO2011060933A1

WO2011060933A1 - Temperature indicator for visually displaying a temperature below the room temperature

Info

Publication number: WO2011060933A1
Application number: PCT/EP2010/007010
Authority: WO
Inventors: Gernot Ludescher; Erhard Lengfeldner
Original assignee: On Point Indicators Gmbh
Priority date: 2009-11-19
Filing date: 2010-11-18
Publication date: 2011-05-26
Also published as: EP2502039A1; DE102009053927A1

Abstract

The invention relates to a thermochromic temperature indicator for visually displaying a temperature of an object below the room temperature for sensing the surface temperature of said object. The invention is characterized in that the surface to be detected is connected either directly to the surface the temperature of which is to be sensed or via highly thermally conductive layers, and in that an insulating layer in the form of a heat insulator is arranged on the face opposite the surface, said heat insulator preventing the influence of a disruptive heat (an undesired influence of heat that leads to an indication error of the indicator) on the temperature indicator.

Description

Temperature indicator for visual indication of a temperature below the

room temperature

The invention relates to a device for the visual display of a temperature of a specimen below the room temperature with protection against the action of undesirable disturbance temperatures. In W0102168A1 an indicator of a transparent laminate with one or more color-changing thermochromic materials is described. The

Layer structure has at least one substantially gas-impermeable or UV light-impermeable layer. A disadvantage of the cited document, however, is that a UV filter layer is needed to protect the underlying thermochromatic layer against UV light. In addition, a gas-tight encapsulation is needed to protect the temperature-sensitive layer against the action of gases.

In the cited document, the disadvantage is given that the temperature-indicating element is not covered by an insulation space and therefore a thermally conductive contact with the overlying layers is given. This has the disadvantage that a temperature effect on one of the upper cover layers is introduced directly in the form of heat conduction to the temperature indicator, which therefore leads to a false indication. This means that such a temperature indicator is not suitable when it comes to the fact that incorrect influences (disturbance temperatures), such. B. an external heat radiation, a warming light radiation or the like should not lead to a false report.

Disadvantage of the cited document WO0102168A1 is accordingly that a heat insulator is missing above the temperature indicator. This has the disadvantage that a harmful effect of heat radiation from above

CONFIRMATION COPY or comes from the outside, be registered directly on the heat-conducting cover layers on the temperature indicator, which therefore leads to a false report.

WO9924799A1 discloses a device for detecting the thawing of frozen food, wherein released liquid water is checked during thawing. The device consists of a laminated layer composite, wherein at least one permeable layer, preferably paper, is used, and the indicator material provides water for the color change when a predetermined temperature is exceeded.

In the known document although a recess is present, which is filled with a liquid or semi-liquid substrate. However, this arrangement is not suitable to prevent false readings when acting from the outside, a temperature change that does not touch the DUT ago. Therefore, the temperature indicator is not suitable for displaying an unwanted indication of a temperature change that is not originated by the DUT.

The invention is therefore compared to this document, the object to provide a temperature indicator for displaying a temperature of a specimen below the room temperature, which does not lead to a false reading when exposed to outside higher temperatures and therefore only indicates a temperature of the DUT itself is generated, on which the temperature indicator is attached. External heat radiation or temperature influences should not lead to a false indication of the temperature indicator. A feature of the invention is therefore that an external external influence, which does not come from the device under test itself, does not lead to a false indication of the temperature indicator. The present description distinguishes between a disturbing temperature acting on the indicator from the outside and opposite the surface of the specimen, which should not lead to a false indication of the indicator and a measuring or detection temperature of a specimen to act on the temperature indicator without interference by the disturbance temperature , An essential feature of the invention is therefore that the surface to be detected is connected directly or via good heat-conducting layers with the temperature or temperature to be detected layer or substrate and that on the, the layer or the substrate side facing away from an insulating layer is arranged in the form of a heat insulator which prevents the action of a disturbing heat (unwanted heat, leading to the false indication of the indicator) on the temperature indicator. In a preferred embodiment, the heat insulator is formed as an air cavity, which is filled with a heat-insulating gas or a good heat-insulating liquid or solid substance.

In the present invention, in a preferred embodiment, a laminate with at least one color-changing material and an overlying, at least partially transparent layer or at least partially transparent film is used.

This layer need not be gas impermeable, but only a spacing to the color changing material needs to be achieved, and this layer must also be UV transparent.

The invention describes a temperature indicator whose structure delays the temperature difference between a substrate and the ambient temperatures such that an underlying temperature-sensitive layer preferably reacts to the substrate temperature without the influence of the ambient temperature.

Temperature-sensitive layers, especially when they move below room temperature, have the disadvantage that the temperature is manipulated by external influences in such a way that it is no longer possible to detect the real object temperature. Likewise, heat is applied in the short term during physical contact or other heat sources, so that a falsified measurement result is achieved. According to the core of the present invention is that the indicator substance is arranged in a recess which faces away from the test object, wherein the recess provides a shelter, which is formed as poor as possible thermally conductive. For this reason, it is preferred if the recess is filled with a sealing gas or air or vacuum, so that this medium, which is to prevent the heat transfer from the recess to the indicator substance, is held as possible sealing in this recess.

It is essential that the best possible or effective heat transfer from the test piece to the underside of the indicator substance is achieved and that the opposite side over which a faulty heat could be registered, provided with poor thermal conductivity, which according to the invention z. B. is achieved by the arrangement of a recess beyond the specimen and above the indicator substance.

Thus, on the one hand, a good and effective heat transfer from the test specimen to the indicator substance is achieved from one side, and from the opposite side a heat transfer to the indicator substance is to be prevented. This creates a temperature gradient between the side of the indicator substance facing the test object and the side of the indicator substance facing away from the test object, which results in only the heat conduction from the test object to the indicator substance being present, and external influences from the opposite side of the test object act on the indicator substance, can no longer reach the indicator substance.

For this purpose, it is provided that the recess is filled with a poorly heat-conductive material, in particular a gas or air or even a vacuum or other, optically at least semi-permeable material, such. As a heat-insulating gel, a heat-insulating liquid or heat-insulating solids.

Such heat-insulating hollow body are preferably formed as (heat insulating trained) glass bubbles, which fill the recess. Here, the height of the recess is to be optimized in relation to the thickness of the indicator substance. It is to be achieved that the insulating cavity surrounds the indicator substance from the side facing away from the test object in order to achieve good thermal insulation there. Accordingly, it is not necessary for the solution that the recess is rectangular in profile. It can also be arcuate. The wall boundary of the recess may also be formed in the form of a protective cap, which is sealingly mounted on the surface of the specimen and below which the indicator substance is applied directly to the specimen.

It is important that the end faces of the indicator substance are held in the worst possible heat-conducting composite to the other surrounding materials, which means that these end faces are not directly connected in heat-conducting contact with the other outwardly facing surfaces of the indicator.

It is therefore a particularly favorable non-thermally conductive layer or environment of the indicator substance with respect to the remote from the sample ambient areas. Therefore, in all exemplary embodiments, the invention assumes that the temperature of the test object or of the test object surface is always lower than the ambient temperature in which the test object is arranged. This means that the specimen is always colder than the ambient temperature and that the heat rays acting on the indicator away from the side facing away from the specimen should not lead to a false reading, but that only the lower temperature of the specimen is displayed correctly.

Therefore, the indicator substance should always be from its nominal value below room temperature, i. H. are in direct thermal contact with the cooler DUT.

Consequently, the indicator substance should be in thermal equilibrium with the surface of the test specimen. The invention accordingly relates to a device by which the temperature difference between a test specimen and ambient temperatures is delayed such that an underlying temperature-sensitive layer (irreversible) perceives it preferably only to the Prüflingstemperatur without influence of the ambient temperature, wherein the thermoreactive layer in fixed contact to the observing DUT is and is separated by an atmospheric protective layer to the environment.

In another embodiment, the temperature-sensitive device reacts to fluctuating temperatures, wherein the indicator side faces the object to be measured and is covered or surrounded by a gaseous protective layer and is protected against unwanted thermal interference.

The thermo-reactive substance has a thermal protection, which retards a thermal equilibrium between two different temperature poles.

The subject of the present invention results not only from the subject matter of the individual claims, but also from the combination of the individual claims with each other.

All information and features disclosed in the documents, including the abstract, in particular the spatial design shown in the drawings, are claimed to be essential to the invention insofar as they are novel individually or in combination with respect to the prior art.

In the following the invention will be explained in more detail with reference to drawings showing only one embodiment. Here are from the drawings and their description further features essential to the invention and advantages of the invention.

Show it:

Figure 1: schematically a section through a first embodiment of a

temperature indicator FIG. 2: the plan view of the temperature indicator according to FIG. 1

Figure 3: an enlarged sectional view through the temperature indicator

according to FIG. 1

FIG. 4 shows an embodiment modified in comparison to FIG

Figure 5: another modification

Figure 6: a third modification

FIG. 7 shows a fourth modification. In FIG. 1, the schematic section through a device () is shown on the surface (9) of an object (0).

The surface (9) and the object (10) exemplify a container in the form of a bottle or a bag, or a box, or a package, or other temperature-sensitive test specimen, wherein the surface (9) the surface of a film or a molded article, and the object may be a liquid or a pasty substance or a food and the like. However, the surface (9) can also be directly the surface of the object (10).

The temperature indicator (1) has a temperature-sensitive, irreversibly color-changing indicator substance (2).

The indicator substance (2) is applied on the surface of a carrier substrate film (5). In a first embodiment, a carrier substrate film (5) is provided, for example and preferably, with an adhesive composite layer (8) and a non-adhesive protective film of non-stick-equipped plastic or paper with a spacer film (3). The spacer film (3) can already have the recess (13) or the recess (13) is in each case only after the assembly the substrates (5, 3) produced by means of a band steel cutting tool or roller cutting tool or by laser or Schneidpiotter.

In a development of the embodiment of the spacer element (3) and the cover film (4), both elements (3, 4) can be manufactured from one part, for example by deep drawing or embossing or injection molding. Quite essential is that the air space (12) comes about and allows the longest possible decoupling of the outside temperature (15) from the object surface temperature (9). This decoupling is to ensure that the indicator material (2) when touching the surface of the temperature indicator, for example with a finger, does not directly assume the finger temperature by thermal conduction. Of course, this decoupling also applies to the transport of the object (10) with the device (1) through a space with a temperature above the activation temperature. The air space (12) on the other side must be largely transparent, so that the color of the indicator material can be visually or automatically recognized depending on the state.

The atmospheric protective layer (12) delays the thermal equilibrium between the temperature of the object (10) and the object surface (9) and thus of the indicator material (2) and the ambient temperature (15), so that a brief increase in the ambient temperature (15) no change in color Episode has.

The spacer element (3) can be formed from a closed-cell or open-cell foam-like film of a few tenths of a thickness to about 5 mm in thickness, preferably 0.3 to 3 mm in thickness, and can have one or both sides Adhesive composite layer (6, 7) are performed. However, the spacer member (3) may also be formed of a cardboard-like material or a composite laminate.

In any case, the spacer element (3) has to be provided with a covering layer (4) or covering film (4), and thereby the insulating air space (12) or the atmospheric protective layer (12) is produced above the indicator (2). The cover layer (4) is made for example of a thin transparent plastic film of PET, PETG, oPP, PVC, PP, PMMA, PC, PE or a compound film of the plastics mentioned. Thicknesses of 9 μιη to 200 μιη, preferably 30 μιη to 100 μιτι used. The film (4) can be designed graphically and in color on the underside or the upper side, and thus instructions for the application of the device (1) can be realized graphically.

The indicator material (2) should in any case be in heat-conducting contact with the surface (9) of the object (10). The substrate layer (5) or the substrate film (5) is very thin with about 9 μιη to about 150 μιτι, in particular 30 μιη to 100 μιη and preferably selected from a thermoplastic and the adhesive layer (8) is only a few 1 μηι to 20 μιτι Thickness. In a specific embodiment, the indicator material (2) can also be arranged on the underside of the substrate film (5) and the adhesive composite layer (8) can be arranged above or recessed. However, it must always be ensured that the indicator substance (2) remains visually recognizable.

As the thermally conductive material Polymethylmethyacrylat is used, which is filled with Leitruß. Just as well can be used with metal powder filled PMMA. For example, the thermally conductive material can be prepared by melting a mixture of 10 to 20 wt .-% nickel and / or silver powder and the corresponding amount of PMMA powder. Furthermore, electrically conductive plastic, for example metal ions doped polyacetylene or polythiophene can be used as the conductive material. Likewise, folienubtrate from

Metals, such as stainless steel, copper or metallized foil are used.

FIG. 3 shows an enlarged sectional representation through the situation according to FIG.

There it can be seen that the air space or cavity should be filled as possible with a poorly heat-conductive material such. B. with an air, a noble gas, a protective gas or a vacuum. It is important that an incident in the direction of arrow 17 on the top of the temperature indicator heat radiation, the z. B. meets the top layer 4, only very much delayed and registered with low heat conduction efficiency according to arrow 18 in the cavity 12.

On the other hand, the cavity 12 is always cooled from the side of the specimen 9, 10 in the direction of arrow 19 with high thermal conductivity and high efficiency, so that the low temperature influence in the direction of arrow 18, which could lead to an increase in temperature in the interior of the air space 12, not up to Surface of the indicator substance 2 comes.

Accordingly, the indicator substance is in good heat-conducting contact with the surface of the object 10 and in poor heat-conducting contact with the environment of the object 10th

FIG. 4 shows, as a modified embodiment, that the recess 13 can also be delimited by a cap 15 on the wall side, which is formed from any heat-insulating material, such as, for example, As a heat-insulating plastic or a laminate, said cap 15 must be at least partially optically transparent to observe the color change of the indicator substance 2 from the outside.

FIG. 5 shows, as a further exemplary embodiment, that it can be provided that a concave recess 16, in which the indicator substance 2 is formed, is arranged in the object surface 9.

This results in a significant space saving, because the overlying structure can now be built much thinner, with the same thermal insulation values are achieved, compared for example with the structure in Figure 3 with the same size ratios and the same heat input.

Of course, all embodiments show an object surface 9 applied to an object 10. It goes without saying in all Embodiments possible to let the object surface 9 coincide with the object 10 itself, so that the recess 16 is present in the object 10.

In principle, consequently, the substrate layer 5 or substrate film can also be dispensed with, and according to the exemplary embodiment according to FIG. 5, the indicator substance 2 can be applied directly to the object surface 9.

FIG. 6 shows, as a further exemplary embodiment, that the heat-insulating structure according to FIG. 5 can also be omitted on the side of the indicator substance 2 facing away from the object surface and that the structure only consists of a cover layer 4 or of a cover film, but which nevertheless has a recess 13 with an air space 12 around the indicator substance 2 forms to complete this heat-insulating upwards, while down to take place in the direction of the object surface optimized heat transfer.

FIG. 7 shows, for all the exemplary embodiments mentioned, that the air space 12 in the recess 13 can also be designed as an insulator filling 21, wherein this insulator filling can be designed as a heat-insulating gel, liquid or solid.

In the illustrated embodiment, the insulator filling 21 consists of hollow glass spheres 22, wherein each glass hollow sphere from about 5 prn to several 100 μητι diameter and also has thermally well insulated properties due to the hollow sphere property.

The temperature indicator can be made of a transparent blister or a deformable film or by injection molding. Drawing temperature indicator

irreversible temperature-sensitive color-changing material (indicator substance)

Spacer element

Cover layer or cover film

Substrate layer or substrate film

Adhesive layer with graphic design

Bonding layer

object surface

object

observer

Airspace or atmospheric protective layer

recess

flap

Cap (partly transparent)

recess

arrow

free space

isolator filling

Hollow glass sphere

Claims

claims

1. temperature indicator (1) with thermochromic color change for the optical display of a temperature of an object (10) below the room temperature for

Detecting the surface temperature of this object (10), characterized in that the surface to be detected (9) is connected directly or via highly thermally conductive layers (5, 8) with the temperature to be detected surface (9) and that on the the surface (9) facing away from an insulating layer (3, 4, 6, 12) is arranged in the form of a heat insulator, the influence of a disturbing heat (unwanted heat, leading to the false indication of the indicator) on the temperature indicator (2) prevented.

2. Temperature indicator according to claim 1, characterized in that the heat insulator is formed as an air cavity, which is filled with a heat-insulating gas or air.

3. Temperature indicator according to claim 1 or 2, characterized in that the heat insulator is filled with a good heat-insulating liquid substance with protection against the action of undesirable disturbance temperatures.

4. Temperature indicator according to one of claims 1 to 3, characterized in that the heat insulator is filled with a good heat-insulating solid substance with protection against the action of unwanted interference temperatures.

5. Temperature indicator according to claim 4, characterized in that the solid, insulating substance consists of filled with a gas or air glass bubbles (22).

6. Temperature indicator according to one of claims 1 to 5, characterized in that it consists of a laminate with at least one color-changing material (2) and an overlying, at least partially transparent layer (4).

7. Temperature indicator according to one of claims 1 to 6, characterized in that the indicator substance (2) in a recess (13) is arranged, which is remote from the object (10), wherein the recess (13) provides a shelter (12) , which is formed thermally conductive poor.

8. Temperature indicator according to one of claims 1 to 7, characterized by an indicator material (2), which is applied to a carrier substrate film (5), and an adhesive composite layer (8) and a protective film (4) made of non-stick plastic or paper, and with a heat insulating trained spacer sheet (3).

9. Temperature indicator according to claim 8, characterized in that in the

Spacer sheet (3), the heat-insulating recess (13) is arranged.

10. Temperature indicator according to one of claims 1 to 9, characterized in that the spacer element (3) of a closed-cell or open-cell foam-like film of a few hundredths of a mm thickness to about 5 mm thickness, preferably 0.3 mm to 3 mm thick, is formed.

11. Temperature indicator according to one of claims 1 to 10, characterized in that the spacer element (3) on one or both sides with an adhesive layer (6, 7) is provided.

12. Temperature indicator according to one of claims 1 to 11, characterized in that the spacer element (3) with a cover layer (4) or cover film (4) is connected, which closes the indicator (2) overlapping recess upwards and thereby the insulating air space or the atmospheric protective layer over the indicator (2) is formed.

13. Temperature indicator according to one of claims 1 to 12, characterized in that the indicator (2) carrying substrate layer (5) consists of a thermally conductive film.

14. Temperature indicator according to claim 13, characterized in that the thermally conductive formed film of the substrate layer (5) consists of polymethylmethacrylate, which is filled with Leitruß.

15. Temperature indicator according to claim 13, characterized in that the thermally conductive formed film of the substrate layer (5) consists of filled with metal powders PMMA.

16. Temperature indicator according to claim 13, characterized in that the thermally conductive film formed the substrate layer (5) by melting a mixture of 10 to 20 wt .-% nickel and / or silver powder and the corresponding amount of PMMA powder.

17. Temperature indicator according to claim 13, characterized in that the thermally conductive formed film of the substrate layer (5) is formed by an electrically conductive plastic consisting of doped with metal ions polyacetylene or polythiophene.

18. Temperature indicator according to one of claims 1 to 17, characterized in that the recess (13) on the wall side by a cap (15) is limited, which closes the indicator substance on the upper side as a heat insulator.

19. Temperature indicator according to one of claims 1 to 17, characterized in that in the object surface (9) a concave recess (16) is arranged, in which the indicator substance (2) is formed

20. Temperature indicator according to one of claims 1 to 19, characterized in that in all embodiments, the object surface 9 coincides with the object 10 itself, so that the recess 16 in the object 10 is present.

21. Temperature indicator according to one of claims 1 to 20, characterized in that in all embodiments, the substrate layer 5 or substrate film omitted, and according to the embodiment of Figure 5, the indicator substance 2 is mounted directly on the object surface 9.

22. Temperature indicator according to one of claims 1-21, characterized in that the insulating film consists of an air-filled foil or webs.

23. Temperature indicator according to one of claims 1-22, characterized in that the insulating film consists of a multilayer overlay composite.