WO2007118933A1

WO2007118933A1 - Method and indicator for monitoring an expiration of a predetermined, temperature-dependent time period

Info

Publication number: WO2007118933A1
Application number: PCT/FI2007/050191
Authority: WO
Inventors: Sami Kivinen; Tom Saxberg; Håkan SAXEN; Ismo Pietari
Original assignee: Upm Raflatac Oy
Priority date: 2006-04-18
Filing date: 2007-04-04
Publication date: 2007-10-25
Also published as: FI20065238A; FI20065238A0

Abstract

An indicator and method for showing an expiration of a predetermined, temperature-dependent time period, which indicator has a first element (1), containing a coating layer (4) and a second element (2) containing an activating layer (10). The indicator is activated while taken into use by placing the first (1) and second element (2) into contact with each other. Before the activation of the indicator in the coating layer (4) there is a visually distinctive colour zone (8) the colour of which changes after the activation of the indicator due to time and temperature effect.

Description

Method and indicator for monitoring an expiration of a predetermined, temperature- dependent time period

Field of Invention

This invention relates to an indicator according to an preamble of accompanying patent claim 1. This invention also relates to a method in accordance with accompanying claim 19 for monitoring an expiration of a predetermined, temperature-dependent time period.

Background of the invention

Substances that are easily perished are manufactured or used as a raw material in certain industrial sectors. These products or substances need to be used within certain time period. Part of them require a certain, relatively regular storage temperature, so that the product quality remains good. Such products include among others certain foodstuffs, drugs, chemicals, adhesives and paints. Preservability of foodstuffs before their usage, including meat, fish and poultry products, is striven to be enhanced by means of different packaging technologies. Different sealed plastic packages are in use, which will prevent migration of oxygen and microbes to the product from the ambient air of the package. The product may be packaged to a vacuum, as well. One expedient is to add shielding gas inside before-mentioned foodstuffs' plastic packages and this way prevent the growth of aerobic, product-deteriorating organisms inside the package.

With before-mentioned packaging technologies and with suitable temperatures for those products the preservability of products has been extended significantly. The use-by date labelled to the consumer package is, however, based on the assumption that the package has remained undamaged and the package has been stored correctly.

One of the most common reasons for contamination of the product before the date labelled in the consumer package is storing the product in a wrong temperature. This can be long-term, in which case storage area of the product, for example, a refrigerator, a cold room or a storage room has its temperature changed for some reason, and this is not immediately noticed. Or short-term, whereupon the item, for example, during the transportation gets into too high or low temperature, which will affect the product preservability. To solve these problems different temperature or time-temperature indicators have been developed. There is another fallacy among consumers regarding use-by dates. Many consumers do not know that the products in opened packages is preserved for less times than in unopened packages. That is the labelled use-by date of the package is not valid anymore, but the product turns unusable before the use-by date in question. Some producers mention about the issue in conjunction with the printed information of the package, but most of the consumers do not read the texts in question. Furthermore, even if the consumer would have read the text in question, most of the consumers do not remember, when a package was opened and how long it has been stored opened. A concrete example of such products include, for example, drugs and cold cuts packages including meat products.

Several solutions have been represented to visually indicate the product usability and premature deterioration for the product user.

One main group is the time- and time/temperature indicators causing a visual alarm signal, which have been arranged either in the same storage space with the product package or attached to the package itself. Such indicators are manufactured so that their components evoke a certain colour reaction in the indicator within a certain time period and/or in a certain temperature. Temperature variations may also speed up or slow the colour reaction. The product user can thus visually notice in the package surface the usability of the product.

A common time/temperature indicator type is based on the colour reaction in a certain matrix. Another common time/temperature indicator type is based on a migration of a certain component of the indicator. Additionally indicators are known, which are based on the combination of the before-mentioned indicator types, in which a certain component gets migrated, in which case it causes a colour reaction in the other matrix.

One of the components in time/temperature indicators presented to be used is a thermal component, such as a thermal paper or label. Base paper in the thermal paper has been coated with the thermal surface coating. A thermal surface coating consists of a colourant in addition to a normal coating substance components, i.e. Pigments, binders and additives,, which colourant is under normal conditions colourless, both from the developer and sensitiser. When a sufficient temperature is directed to the paper, the paper changes its colour. The colour change is caused by the chemical reaction in the coating. Due to the temperature the coating changes soluble and chemicals in it get into the contact with each other and react, which results in the colour formation. Printers using thermal paper are equipped with small thermal resistors, which suitably heated produce a desired printing. In a thermal label on the other side of the base paper there is an adhesive spread, with which the label can be glued on its target.

One such time/temperature indicator utilising a thermal label as a part of the indicator is disclosed in US Patent 6,544,925. The indicator is used to monitor shelf life of easily perishable substances, such as food and drugs. The indicator has two elements, one of which includes a thermosensitive label and the other an adhesive layer including an activating agent. When the time/temperature indicator is activated, the elements are glued one on the other so that the adhesive layer containing the activating agent gets into the contact with the thermal layer of the thermal label. The activating agent evokes a colour formation reaction in the thermal layer, which is visually detectable in the indicator. The total colour formation is evoked after a certain time period or when a certain time/temperature integral has advanced into the suitable stage. The activating agent is selected so that it either reacts with a reactive agent in the thermal label directly and evokes the colour formation or it evokes the reaction conditions, in which the colour change is evoked in a lower temperature than normally.

The problem of this indicator is the reversibility of the reactions between its different layers. It is possible that the activated indicator is contaminated, for example, fat or oil gets into it, in which case the colour formation reaction does not start at all, or already formed colour vanishes.

And because the colour is not shown, it is for the consumer an indication of the product being still usable. This can be very harmful in regard to certain products.

Short description of the invention

Target of the present invention disclosed here is to generate a new indicator to monitor usability of easily perishable products. The indicator gives a visual alarm signal, once the product, to which the indicator is attached, turns unusable within a time period or due to a time and temperature effect. The target is also to generate a method for monitoring an expiration of a predetermined, temperature-dependent time period.

To realise this target an indicator in accordance with the invention is mainly characterised by the features that are disclosed in the characterising part of independent claim 1. A method in accordance with the invention is for its part mainly characterised by the features represented in the characterising part of independent claim 19. In other, dependent patent claims some of the preferred embodiments of the invention are represented.

The invention is based on the idea that there is an activating layer in the indicator containing elements, which evoke colour changing in the colour zone formed in the indicator.

The indicator has two elements, the first of which has a coating layer containing a colour zone. The colour zone has been formed in the indicator before its activation. The coating layer may be a printing ink or colour that is pigmented in itself. The coating layer can also include components, which under the effect of an external impulse react with each other and cause the colour formation into the coating layer. The external impulse can be, for example, heat or pressure. One possibility is to form a coating layer of the thermal surface coating, in which case heat is used as the external impulse directed to it.

The second element of the indicator has an activating layer. When the indicator is activated, the first and second element are brought to contacts with each other so that the activating layer constituents of the second element can react with the coating layer components of the first element. The activating layer includes constituents, which will evoke the colour change in the components forming the colour zone, which will result in either a colour change or even vanishing. To colour change can be described by means of simplified reaction equations as follows:

C(A ₊ B) + D -> A + B + D (1)

C(A ₊ B) + D -> C(A ₊ D) + B (2)

In which C(A + B) = colour included by the colour zone and A and B = components forming the color in the reaction (1) D is an agent, which is able to cause chemical distribution and colour changing of pigmented compound C(A + B) formed by components A and B.

In the reaction (2) D is an agent, which is able to cause disappearance or change of the colour in components A and B. In this reaction, D displaces the other one of colour forming components forming a new compound C(A + D), which is colourless or the colour of which has substantially changed from original. Colour forming components may naturally exist more than the reaction equations (1) and (2) describe. Changing of the colour works as a visual signal for the product user stating that the use-by date of the product draws closer or is passed.

The composition for the activating layer is selected so that the changing of the colour in the colour zone occurs in suitable time for each product, so that when sell-by date or use-by date of the product comes, the colour has substantially changed. Depending on the indicator type, the colour may vanish in the colour zone completely, or its tone changes significantly. If desired, the indicator may include a descriptive scale of the colour changes, in which advances in colour changes are indicated and in which one can visually notice the remaining time period before the sale-by date or use-by date of the product. The activating layer includes constituents, which will evoke the change in the components forming the colour of the colour zone in the coating layer of the first element. These constituents are small molecular agents, which are able to displace gradually at least one component in the colour compound and thus evoke the colourant distribution and colour change. The colour disintegrating constituent is, for example, softener or oil. The oil may be vegetable or mineral or synthetic oil.

Onto the coating layer a protective layer may be formed, which protects the coating layer before activating the indicator. With a suitable material choice for the protective layer and suitable thickness of the protective layer it may be possible to adjust the time period taken for the change of the indicator colour. By means of the protective layer advancing of the colour change may be slowed or speeded up.

The protective layer may be, for instance, a polymer film or lacquer layer. By selecting suitable constituents for constituents of the activating layer and by selecting their quantities properly and by selecting a suitable protective layer and its thickness the advancing of the colour change can be affected. The constituents of the activating layer are selected so that they also react to temperature variations. By altering the reactive constituent and by changing its layer composition the reaction speed and temperature dependence can be adjusted. At its simplest the indicator comprises of two self-adhesive labels, one of which has been formed as the first element and the other as the second element. The activating layer in the other element can be, for example, an adhesive layer, by which the second element is fastened to the first element. Activating the indicator is carried out by arranging the second element to the surface of the first element. According to an embodiment of the invention the first element consists of a self-adhesive label, whose coating layer consists of to a base paper pressed or printed printing ink or colour.

According to another embodiment of the invention the first element consists of a thermal label, to whose thermal coating layer a colour zone has been formed before activating the indicator.

The biggest and generally known problem of thermal paper and labels is that the printing holds badly on them.

The print will lighten under certain conditions very rapidly, vanishing ultimately completely so that, for example, text of the sales receipts is impossible to read. The invention uses in a novel way this bad quality of thermal papers for its own benefit and the indicator is generated, in which colour components already formed to the thermal paper are controllably separated and a controlled colour loss in the colour zone is evoked.

The advantage of the indicator in accordance with the invention is its ease of use.

The indicator is easy to fasten to the product packages and its activation is also easy. The visual signal it is giving, I.e. Monitoring colour changes by the naked eye is easy, and does not require separate equipment. Particularly the indicator offers benefits to an ordinary consumer, who can with the help of it easily to notice the product usability and manages to avoid the problems caused by a spoiled product.

The reaction given by the indicator is also reliable. Reactions between different layers of the indicator are irreversible. This means that in case of the indicator contamination takes place, it results in the colour change reaction acceleration in the colour zone. A consumer would thus get the information of the product deterioration earlier than a product is in effect perished. This information results only in discarding the product, and does not put consumers in danger.

Brief description of the figures

In the following the invention is disclosed more exactly by referring to the accompanying figures, where

Figure Ia illustrates schematically a first element used in the indicator as a cross-section,

Figure Ib illustrates schematically another first element used in the indicator as a cross-section, Figure Ic illustrates schematically yet another first element used in the indicator as a cross-section,

Figure 2 illustrates schematically a second element used in the indicator as a cross-section,

Figure 3 illustrates schematically an activated indicator as a cross-section,

Figure 4a illustrates an unactivated indicator as a partial perspective drawing,

Figure 4b illustrates a crosscut of the indicator in accordance of Figure 4a and

Figures 5a, 5b and 5c illustrate time and/or temperature effect regarding the colour change in the colour zone of the activated indicator as seen from above.

Detailed description of the invention

Figure Ia illustrates a crosscut of a first element 1 belonging to the indicator. Element 1 is a self- adhesive label product, which consists of a base, i.e. Of a base paper or film 3, on the other side of which a coating layer 4 is formed. As the coating layer a thermal coating layer is used in this embodiment illustrated in the figure. On the other side of the base paper 3 there is an adhesive layer 5, to which it is fixed a separable backing paper 6.

Figure Ib illustrates a crosscut of another first element 1 belonging to the indicator. At this embodiment, the coating layer 4 is protected with the protective layer 7. Other parts of the first element are identical to the illustrated elements of Figure Ia. The protective layer 7 is not necessary for the indicator functionality and, if desired, it can be excluded.

In figures Ia and Ib the first element 1 is illustrated in the situation, in which it is not yet fastened to the product to-be-monitored, but in which parts of it have already been subjected to heat and in the thermal coating layer 4 a colour formation reaction has been evoked, which results in the formation of a colour zone 8. The colour zone 8 may be any colour zone, such as a figure or text, printed or pressed with conventional heat utilising methods to the first element. It can also include text or symbols.

Figure Ic illustrates a crosscut of yet another first element 1 belonging to the indicator. In this embodiment, the coating layer 4' is formed of printing ink or colour, which has been pressed or printed to the base 3. The coating layer 4' may form a colour zone 8 comprising figure / figures, text or symbols. If desired, the coating layer can be also protected with a protective layer in this embodiment. Figure 2 illustrates a crosscut of the second element 2 belonging to the indicator, which functions as an activating element of the indicator. The second element 2 is also a self-adhesive label product containing a base 9, which is a transparent paper or film, the other side of which there is an activating layer, in this embodiment an adhesive layer 10, to which it is fixed a separable backing paper 11.

Figure 3 illustrates a crosscut of the indicator, which has been glued to an outer surface 12 of the package containing an easily perishable product to-be-monitored. The indicator has been activated by fastening the second element 2 onto the first element 1.

An adhesive used in the adhesive layer of the second element 2 includes constituents, which will evoke a change in colour forming components of the colour zone 8 and the colour change, in this case, a loss of colour. In Figure 3 colour which was in the colour zone 8 has completely vanished. Broken lines 13 delimit the space, in which the colour zone 8 was situated prior to the activation. In figures 4a and 4b an embodiment has been disclosed regarding the indicator to be fastened to the product package, in which the first element 1 and the second element 2 have been fastened to each other for an uniform easy-to-use indicator.

The indicator is not yet activated. At least the other one of the elements has been formed so that for the extension of its one side it has been arranged an indication section 14 to facilitate the colour change monitoring of the indicator.

The indication section is printed, conventional paper or film. The indication section has a scale 15, to which it is printed different colours shades occuring during the colour distribution. Beside each colour shade it is printed a verbal symbol or text 16, which explains the meaning of the colour shade in question. In the example of the figure the description printed for the total colour vanishing is 'Use-by date expired.' Also for the other phases of the colour change a verbal text may be written to replace letters A, B or C presented in the figure.

The indication section 14 may be arranged to either one of the elements 1 or 2.

Most conveniently it has been arranged to the first element 1, which has been fastened to the product package to-be-monitored. An indication section 14b arranged to the second element 2 is of a transparent film, whose surface against the first element 1 has adhesive, by which the indication section of the second element 2 is fastened onto the indication section 14a of the first element 1. Indication section's scale of the first element can be viewed through the film-like indication section of the second element.

Figure 4b illustrates an unactivated indicator in accordance with Figure 4a as a crosscut. The indication sections 14a and 14b of the first and second element respectively have been fastened one on the other. The second element 2 has still a backing paper 11 in place to protect the activating layer 10 beneath it. Into the coating layer 4 of the first element 1 the colour zone 8 has been formed, which in this example covers the whole coating layer area. When the indicator is activated, the backing paper 11 is removed and the second element 2 is fastened to the first element 1. This starts the changing reaction of the colour.

Figures 5a, 5b and 5c illustrate time and/or temperature effect on the colour change of the colour zone 8. hi Figure 5a the indicator has been activated and the colour zone 8 is very dark. In Figure 5b the colour of the colour zone 8 is clearly lighter and in Figure 5c the colour of colour zone is completely vanished. Vanishing of the colour is an indication of the deterioration of the product quality and that the product is unusable. The consumer may monitor the colour change and compare it with the scale of the indication section and consequently get the information of the remaining usage time of the product.

The first element 1 may be any commercially usable thermal label or sticker. It is essential that components included in the used thermal coating layer and the activating agents of the second element's activating layer react with each other and produce a desired colour changing reaction. As a thermal label base either paper or film can be used.

The coating layer formed to the second element may be not only an adhesive layer, but also a lacquer layer or heat-sealable film that includes constituents that decompose the colour of the colour zone.

The invention is not meant to be limited to the embodiments disclosed before as examples, but the invention is intended to be applicable comprehensively within the inventive concept of the following patent claims.

The indicator may be glued to the outer surface packages of all such products, products of which change unusable can not be without opening the package or otherwise identified, hi general, for such products there is specified a so-called use-by date, which is most often labelled to the package, but which all consumers do not notice or find. These products include for example food products, chemicals, cosmetics and drugs. Also raw materials for the industrial use can be equipped with the indicator. In these cases the indicator is activated by the packer of the product. A particularly suitable application for the indicator is consumer-sellable products, the preservability of which after opening of the package is limited, such as food products and drugs. In these cases the consumer by herself/himself activates the indicator while opening the package.

Claims

1. An indicator for showing an expiration of a predetermined, temperature-dependent time period, which indicator has

- a first element (1), containing a coating layer (4), and

- a second element (2) containing an activating layer (10), which indicator while taken into use is activated by placing the first (1) and second element (2) into contact with each other, characterised in that in a coating layer (4, 4') there is before activating the indicator a visually distinctive colour zone (8), the colour of which changes after the activation of the indicator due to time and temperature effect.

2. The indicator according to claim 1, characterised in that in the coating layer (4) due to an effect of an external impulse a visually distinctive colour zone (8) can be evoked.

3. An indicator according to claim 2, characterised in that the coating layer (4) is a thermal coating layer.

4. The indicator according to any of previous claims 1 - 3, characterised in that in the coating layer (4) the visually distinctive colour zone (8) has been formed before activating the indicator.

5. The indicator according to claim 1, characterised in that the coating layer (4') is a printing ink or printing colour.

6. The indicator according to claim 1, characterised in that the activating layer (10) is one of the following: adhesive layer, lacquer layer or film.

7. The indicator according to claim 6, characterised in that the activating layer (10) has at least one ingredient, which evokes a change in the components forming the colour in the coating layer (4, 4') formed in the colour zone (8), which will result in a changing of the colour.

8. The indicator according to claim 6, characterised in that the activating layer (10) includes small- molecular elements, such as oils.

9. The indicator according to claim 1, characterised in that the indicator has been arranged to be activated by placing the activating layer (10) of the second element (2) into contact with the coating layer (4, 4') of the first element (1).

10. The indicator according to claim 1, characterised in that onto the coating layer (4) a protective layer (7) has been formed.

11. The indicator according to claim 10, characterised in that the indicator has been arranged to be activated by placing the activating layer (10) of the second element (2) into contact with the protective layer (7) of the first element (1).

12. The indicator according to claim 1, characterised in that after activation of the indicator in the coating layer (4, 4') the visually distinctive colour zone (8) lightens.

13. The indicator according to claim 1, characterised in that after the activation of the indicator in the coating layer (4, 4') the visually distinctive colour zone (8) gradually vanishes completely.

14. The indicator according to claim 7 or 10, characterised in that thickness or composition of the activating layer (10) and/or protective layer (7) is selected so that by changing it a colour changing speed of the colour zone (8) is adjusted.

15. The indicator according to claim 7 or 10, characterised in that the composition of the activating layer (10) and/or protective layer (7) is selected so that temperature affects the colour changing speed of the colour zone (8).

16. The indicator according to claim 1, characterised in that in the first element (1) there is an adhesive layer (6) to fasten the first element to the product package surface (12).

17. The indicator according to any of the previous claims 1 - 4, characterised in that the first element (1) is a thermal label.

18. The indicator according to claim 16, characterised in that the product package (17), on a surface (12) of which the indicator has been fastened, includes easily perishable products, such as food products, chemicals, cosmetics and drugs.

19. a method for monitoring an expiration of a predetermined, temperature-dependent time period, in which method an activatable indicator is used, which indicator has

- a first element (1), containing a coating layer (4) and

- a second element (2) containing an activating layer (10), which indicator is activated while taken into use by placing the first (1) and second element (2) into contact with each other, characterised in that in the coating layer (4, 4') a visually distinctive colour zone (8) has been formed before activating the indicator the colour of which changes after the activation of the indicator due to time and temperature effect.

20. The method according to claim 19, characterised in that to the coating layer (4) is directed an external impulse, under the effect of which in the coating layer (4) the visually distinctive colour zone (8) is formed.

21. The method according to claim 19, characterised in that the coating layer (4) is a thermal coating layer.

22. The method according to claims 19 - 21, characterised in that before the activation of the indicator the first element (1) is treated so that in the coating layer (4) the visually distinctive colour zone (8) is formed.

23. The method according to claim 19, characterised in that the coating layer is a printing ink or a printing colour.

24. The method according to claim 19, characterised in that the activating layer (10) is one of the following: adhesive layer, lacquer layer or film.

25. The method according to claim 24, characterised in that the activating layer (10) has at least one ingredient, which evokes a change in the components forming the colour in the colour zone (8) formed in the coating layer (4, 4'), which will result in a changing of the colour.

26. The method according to claim 24, characterised in that the activating layer (10) includes small-molecular elements, such as oils.

27. The method according to claim 19, characterised in that the indicator is activated by placing the activating layer (10) of the second element (2) into contact with the coating layer (4, 4') of the first element (1).

28. The method according to claim 19, characterised in that onto the coating (4, 4') it is formed a protective layer (7).

29. The method according to claim 28, characterised in that the indicator is activated by placing the activating layer (10) of the second element (2) into contact with the protective layer (7) of the first element (1).

30. The method according to claim 19, characterised in that after the activation of the indicator in the coating layer (4, 4') the visually distinctive colour zone (8) lightens.

31. The method according to claim 19, characterised in that after the activation of the indicator in the coating layer (4, 4¹) the visually distinctive colour zone (8) gradually vanishes completely.

32. The method according to claim 25 or 28, characterised in that a colour changing speed of the colour zone (8) is adjusted by changing the thickness or composition of the activating layer (10) and/or protective layer (7).

33. The method according to claim 25 or 28, characterised in that the composition of the activating layer (10) and/or protective layer (7) is selected so that temperature affects the colour changing speed of the colour zone (8).

34. The method according to claim 19, characterised in that the adhesive layer (6) is arranged to the first element (1) to fasten the first element to the product package surface (12).

35. The method according to claim 19 or 21, characterised in that the first element (1) is a thermal label.

36. The method according to claim 34, characterised in that the product package (17), on a surface (12) of which the indicator has been fastened, includes easily perishable products, such as food products, chemicals, cosmetics and drugs.