This invention relates to a method for equipping packages with indicators, as described in the introduction to Patent Claim 1, and to an indicator system, as described in the introduction to Patent Claim 9.

The method and indicator system included in the invention (hereafter referred to as "the invention") are applicable to indicators based on colour reactions, used for instance in food industry packaging.

Producers in the food industry strive to maximise their prod- ucts' shelf lives without jeopardising their quality. Shelf lives are determined with tests which cannot take into account factors such as the deterioration of foodstuffs due to breakage of packaging or incorrect storage conditions. This is why indicators have been developed which indicate the ac- tual state of the product. Examples are time/temperature indicators, leak indicators which respond to oxygen, and deterioration indicators based on various compounds released during deterioration. These indicators are usually manufactured as separate stickers, which contain both the necessary infor- mation for interpreting the indicator and the reactive indicator material.

Thus the indicator solutions known until now contain both the indicating - i.e. reactive - material and the information needed for interpreting the indicator. One problem with these known indicator solutions is that their manufacturing process is often complex and difficult, because in addition to the process of producing the indicator, it has to be printed with text.

The complexity of the production process is compounded by the fact that the foodstuffs for which the packaging is used may vary greatly, which means that the sensitivity of the indicators must vary accordingly. This means that many slightly

different product-specific indicators must be produced using expensive and complicated production processes.

Some companies request personalised indicator structures, for instance in the shape of their company logos. This complicates the indicator production process for the known solutions, as the personalisation demands must be taken into account already during production.

Another problem is the fact that many printing houses use UV inks which are unsuitable for use with foodstuffs. In other words, those inks cannot be used on existing indicator structures. A further problem is the fact that the printing ink on indicators placed inside packaging, even if it is suitable for foodstuffs, may have a deteriorating effect on the quality or perceived quality of the foodstuffs, for instance by- dyeing the product a strange colour.

The aim of this invention is to remove the problems described above and to create an affordable and simple method for equipping packages with indicators, thus also simplifying the indicator production process. The invention also aims to create a simple, safe and variable indicator system in which the same basic indicator structure can be applied to many differ- ent uses. The method created in accordance with the invention is characterised by the factors described in the characteristics section of Patent Claim 1. Further, the indicator system created in accordance with the invention is characterised by the factors described in the characteristics section of Pat- ent Claim 9. The other forms of application of the invention are characterised by factors described in the other patent claims.

The benefit of the invention lies in the fact that the indi- cator production process uses generally applicable indicator structures and shapes, which can be placed inside packages.

In other words, the indicators can be of almost any structure

and shape. They could for instance be shaped like a strip, from which suitably sized pieces can be cut for use in packaging. A further benefit is the low cost of production, as the indicators can be produced in large batches. No informa- tion or colour patterns need to be printed on the indicator itself. An essential aspect of the invention is that all information related to interpreting the indicator is printed on the outside of the package, either onto the package itself or onto a label which is then stuck to the package. Another benefit is that indicators can be produced with generally applicable structures and shapes but with several different sensitivity areas, which means that the same indicator model can be used for many products and purposes. In comparison, existing technologies require that product-specific indica- tors be produced for different products. Another benefit is that the indicators can be produced uniformly, while personalised indicator solutions can be created with the patterns printed onto the packaging or the labels to be stuck onto the packaging. A further benefit is that the information needed for interpreting the indicator can be printed using printing inks and labels which are not safe for use in contact with foodstuffs - e.g. UV printing inks - because it is printed or stuck on the outside of the packaging.

Below are detailed descriptions of the invention using application examples and referring to the following Figures, in which:

Figure 1 shows a simplified graphic of an indicator system for packages, made in accordance with the invention, viewed from the side;

Figure 2 shows a simplified graphic of different indicator systems for packages, made in accordance with the invention, viewed from the side;

Figure 3 shows a personalised indicator system made in accordance with the invention, viewed from above the package;

Figure 4 shows an indicator system in which colour changes in the indicator can be interpreted with the help of a scale, made in accordance with the invention, viewed from above the package;

Figure 5 shows a different indicator system in which colour changes in the indicator can be interpreted with the help of a scale, made in accordance with the invention, viewed from above the package;

Figure 6 shows a simplified graphic of an indicator system for packages, using an indicator which reacts in different areas of sensitivity, made in accordance with the invention, viewed from the side;

Figures 1, 2 and 6 show simplified graphics of indicator systems made in accordance with the invention, viewed from the side. The indicator system is implemented such that an indicator sticker, 1, is placed inside a package consisting of transparent packaging film, 2, and indicator sticker 1 is viewed through transparent packaging film 2 or through label 3, stuck onto the film. The information related to interpreting and using indicator 1 is printed onto label 3, which will be stuck onto the outside of the package, at the same time as the label is printed. If there is no label, the information is printed onto the surface of packaging film 2, e.g. at a time when other printing work is done.

For the package in Figure Ia, label 3 has been equipped with a hole, 4, made in the desired shape e.g. by die-cutting. Hole 4 is placed in line with indicator 1, which is stuck onto transparent packaging film 2 on the

inside of the package. Thus changes in colour on indicator 1 can be observed through hole 4 and through transparent packaging film 2. An essential aspect is that all the information, instructions, illustrations and colours needed for interpreting the indicator are printed on label 3.

Similarly, Figure Ib shows a solution according to Figure Ia, where hole 4 is covered with protective film 5. Depending on the structure of protective film 5, it can be used for several different purposes. Protective film 5 could be an ultraviolet-ray absorbent film or a colour film which emphasises the indicator's colour changes. In addition, protective film 5 could be silicon-coated to repel dirt or a simple film to protect against scratches. Protective film 5 can also be a tearable, flap-style film which is not removed until someone wishes to read the indicator. In this case, protective film 5 can consist for instance of a thin aluminium foil or a similar, good protector against UV rays.

Figure Ic shows an indicator system made in accordance with the invention, in which the information related to the product and the information related to the interpretation of indicator 1 are both printed onto label 3, which is stuck on the outside of the package, while indicator 1 is placed on the inside of the package consisting of packaging film 2, next to label 3. In this arrangement, label 3 does not need a separate hole through which indicator 1 can be read.

Figure 2a shows an indicator system made in accordance with the invention, in which label 6, which contains the information related to the product and the information related to the interpretation of indicator 1, printed onto label 6 with printing ink 7, is transparent and is stuck onto the outer surface of packaging film 2. Label 6 is printed so that an area, 4a, is left free of any printing ink. At the

same time, indicator 1 is attached to the inside surface of packaging film 2 in line with transparent area 4a, which is free of printing ink. In this solution, indicator 1 is read through ink-free area 4a on label 6 and through transparent packaging film 2.

Figure 2b shows an indicator system made in accordance with the invention, in which the information related to the product and the information related to the interpretation of indicator 1, are printed onto the outer surface of transparent packaging film 2 with printing ink 7, such that area 4a is left free of any printing ink. Indicator 1 is attached to the inside surface of packaging film 2 in line with transparent area 4a, which is free of printing ink. In this solution, indicator 1 is read through ink-free area 4a on transparent packaging film 2.

Figures 3, 4 and 5 display indicator systems made in accordance with the application system described in the inven- tion, viewed from above. In principle, the layer structures of the indicator systems are similar to those shown in Figures 1 and 2. In these cases, the indicator is placed on the inside of the packaging, and the information needed for interpreting the indicator is printed either onto a label or onto the outer surface of the packaging material. Figures 3, 4 and 5 show some alternative types of indicators, which can be used in accordance with the indicator systems described in the invention.

Figures 3a and 3b show personalised indicator systems, which are easy to create in accordance with the invention. In Figure 3a, the area surrounding indicator 1, which is placed inside the package, is dyed on the outside of the packaging with reference dye 8, which is the same colour as indicator 1 when the indicator has reacted. Figure 3a shows a label, 3, equipped e.g. through die-cutting with a hole in the desired shape - in this case that of the company' s

logo. Label 3 is printed with reference dye 8. Label 3 can also simultaneously be printed with other information needed for interpreting the indicator, or with product information, etc. Reference dye 8, with its patterns and in- formation, can also be printed directly onto the outside of the packaging film. On the left of Figure 3a, indicator 1 has not reacted and the company' s logo is clearly visible within reference dye 8. Meanwhile, on the right of Figure 3a, indicator 1 has begun reacting and the colour of the pattern located within reference dye 8 has begun to resemble reference dye 8, as the colour of the indicator changes. When indicator 1 has reacted completely, it will have changed to be exactly the colour of reference dye 8 and the logo will be invisible.

Figure 3b shows a similar indicator system to that in Figure 3a, except that the reference dye, 9, has been selected so that it is the same colour, when seen from above, as indicator 1 when no reaction has taken place in indicator 1. On the left of figure 3b, indicator 1 has not reacted and the company' s logo, selected as the pattern, is invisible within reference dye 9. Meanwhile, on the right of Figure 3b, indicator 1 has begun reacting and the colour of the pattern located within reference dye 9 has begun to change so that the pattern is beginning to be visible within reference dye 9.

In these personalised indicator solutions, the colours of the reference dye, 9, and of the indicator, 1, have been selected so that, as a reaction is produced in indicator 1 and the colour of the indicator changes, the hole cut into the shape of the company logo either disappears from view or, if it was initially invisible, appears.

Figure 4 shows a solution in accordance to the invention, which incorporates a scale, 10. Different reference dyes, w, x, y and z, have been placed on the scale to represent

different stages of the reaction. Scale 10 can be in the shape of a circle, for example, with four evenly sized sectors dyed with the different colours w, x, y and z. In the middle of scale 10 there is a concentric hole, 4b, through which indicator 1, placed within the packaging, can be seen. Scale 10 can be linked to a specific variable, such as time, in which case the indicators used will be so-called time/temperature indicators. Similarly, scale 10 can be linked to the concentration of a specific reactant chemical, in which case the indicators used will be for instance oxygen or hydrogen sulphide indicators. Indicator 1, which is visible through hole 4b on scale 10, changes colour slowly as the reaction progresses. The colour of indicator 1 can be compared to the reference dyes w, x, y and z printed on scale 10. On the left of Figure 4, indicator 1 has not yet begun reacting. In the middle, indicator 1 is the colour of reference dye w. On the right, the reaction has progressed so far that indicator 1 is the colour of reference dye y.

In the solution displayed in Figure 5, the indicator structure is such that a whole section of the indicating surface of indicator 1 reacts and finishes reacting before the reaction moves on to the next section of the indicator sur- face. A scale, 11, equipped with a rectangular hole, 4b, with the help of which the progress of the reaction on the indicator surface of indicator 1, which is placed on the inside of the packaging in line with scale 11, can be interpreted, is printed onto the outside of the package, ei- ther onto a label or directly onto the packaging material. These kinds of reactions, which progress in a specific order, can be achieved for instance by coating the surface of indicator 1 in protective coatings of different thicknesses. The reaction progresses most quickly in the areas with the thinnest coating. Another possibility is a structure in which the reactant gas is only allowed to access indicator 1 from a specific point, in which case the reac-

tion will begin spreading from this point to elsewhere on indicator 1. This can be achieved for example by leaving a small channel with no adhesive on the adhesive side of indicator 1. The gas passes through this channel in between the inside of the packaging and the indicator, and the reaction begins on indicator 1 at the end of the channel and progresses along the indicator so that the progress of the reaction can be followed on scale 11. In addition to the scale, the label or packaging is printed with any other information needed for interpreting the indicator.

The solution in Figures 6a and 6b is structured so that different parts of indicator 1, attached on the inside of the packaging, have different levels of sensitivity, indi- eating for example different concentrations of the reactant substance. In other words, the concentration would be highest at one end of indicator 1 and lowest at the other end. Thus the same indicator can be used e.g. in differently sized packages by making a hole, 4, made e.g. by die- cutting for the purpose of viewing indicator 1, in label 3 on the outside of the packaging to align with the part of indicator 1 which has the sensitivity level needed for that package. It is also possible to die-cut holes, 4, in several parts of label 3, which would create a scale consist- ing of the holes.

Thus, in the invention, at least one indicator, 1, which reacts to changes in the product inside the packaging, is placed on the inside of a package consisting of packaging film 2, which is at least partly transparent. The package is equipped with the information needed for interpreting indicator 1 such that at least the main part of the information is located on the outside of the package. According to the process, at least one indicator, 1, of a type which can be used for various different purposes and of a generally applicable shape, for instance mass-produced as a standard product, is placed inside the package, and, depending on the purpose, at

least the main part of the information needed to interpret indicator 1 is placed on the outside of the package, partly or wholly overlapping with indicator 1. The information needed to interpret indicator 1, or at least most of it, is printed onto a separate label, 3, to be stuck onto the outside of the packaging, either separately or simultaneously with other printing work. In addition, the label to be stuck on the outside of the package, label 3, is equipped with a hole, 4, in the desired shape. When the label is stuck onto the packaging, hole 4 is placed in line with indicator 1 on the inside of the package, such that indicator 1 can be read through hole 4. A second application of the invention is that the information needed to interpret indicator 1 is printed directly onto the outer surface of the packaging film, 2. In this case, instead of hole 4, an area, 4a, free of printing ink is left in the information printed on the outside of the packaging, so that when indicator 1 is attached on the inside of the packaging in line with area 4a, indicator 1 can be read through this area which is free of printing ink.

Professionals in the field will clearly see that the invention is not limited to the application examples given above, but can be varied within the scope of the patent claims given below. Thus e.g. the indicator system shown in Figure 3 could be made so that reference dye 8 or 9 is located next to the indicator, but the rest of the information needed for interpreting the indicator is on the outside of the package. In this case hole 4 or area 4a free of printing ink must be made large enough that both the pat- tern and the area dyed with reference dye 8 or 9 surrounding the pattern are visible through packaging film 2.

It will also be obvious to professionals in the field that different applications of this invention can be combined. One beneficial way of combining different applications of this invention is to use a multilayered indicator in accordance with Figure 6 together with scales in accordance with

Figures 4 and 5, which will allow for a large number of variations.