WO1999031501A1

WO1999031501A1 - Method and device for activating an indicator

Info

Publication number: WO1999031501A1
Application number: PCT/SE1998/001908
Authority: WO
Inventors: Christer Ahlberg; Henning Laursen
Original assignee: Visual Indicator Tag Systems - Vitsab Ab
Priority date: 1997-11-27
Filing date: 1998-10-22
Publication date: 1999-06-24
Also published as: SE9704362D0; AU9769598A; SE9704362L; SE508602C2

Abstract

A method and a device for activating an indicator which comprises two liquid-filled ampoules (19, 20) separated by a rupturable partition (21) are disclosed. The method is characterised by exerting a compressive force for breaking the partition (21) and mixing the liquid in the ampoules by moving pressure-exerting means, preferably rolls (10-15), in a path relative to the indicator, alternatingly along the central portion of the indicator and along the edge portions of the indicator. Preferably the exertion of pressure on the central and edge portions of the indicator is repeated at least once. The device comprises pressure-exerting means (10-15) which are movable relative to the indicator in a path passing the indicator. Each pressure-exerting means (10-15) has a width smaller than the extent of the indicator transversely of the path of the pressure-exerting means relative to the indicator. A first pressure-exerting means (10) is arranged to pass in its path the central portion of the indicator. A second and a third pressure-exerting means (10, 12) are arranged to pass in their paths the edge portions of the indicator. Preferably the pressure-exerting means (10-15) are rolls, and it is particularly preferred that all rolls are arranged on a common axis (16), and that all rolls constitute an integrated cylindrical unit (9), the individual rolls being formed of ridges (10, 15) of the cylinder (9).

Description

METHOD AND DEVICE FOR ACTIVATING AN INDICATOR

Field of the Invention

The present invention relates to a method and a device for activating an indicator comprising two liquid-filled ampoules separated by a rupturable par- tition.

Background Art

There are a large number of different products, such as foodstuffs, pharmaceutical preparations, vaccines, blood products, photographic film etc. which are sensitive and should be stored or handled at a certain temperature for a limited time so as not to impair the quality thereof. Particularly well-known examples of such products are foodstuffs, such as refrigerated foodstuffs, e.g. milk, vegetables, shellfish such as shrimps, fish, minced meat etc., or deep-frozen foodstuffs, e.g. meat, fish and ice-cream. For e.g. a deep-frozen product to exhibit quality among consumers, it should not be exposed to a temperature above, for instance, about - 18 °C from the moment the deep-frozen product leaves the producer and up to the moment it reaches the consumer. For refrigerated foodstuffs, the corresponding temperature is from about +4 to +8°C. The route of a frozen food product from the producer to the consumer comprises a large number of steps, such as storage at the producer's place, transport from the producer to the wholesale dealer, storage at the wholesale dealer's place, transport from the wholesale dealer to the retail dealer, and storage at the retail dealer's place. In all these partial steps, the deep-frozen product must be handled correctly, i.e. at a temperature not exceeding about -18 °C for its quality not to be impaired. With a view to ensuring that this occurs, the temperature of the product is checked at regular intervals in each partial step, i.e. in transport and storage. Refrigerated products are checked correspondingly.

It is known to check the handling conditions of sensitive products by using indicators of different types, i.e. devices which by a visual change, such as colour change, indicate a change of the handling conditions of a product.

A preferred type of indicator indicates the temperature as a function of time, i.e. it integrates the tem- perature over time. Various time-temperature-sensitive indicators of this type are known, but a particularly preferred type consists of time-temperature-sensitive, enzymatic indicators as disclosed in US Patents 4,043,871 and 4,284,719. As stated in the latter patent, such an indicator may comprise two small closed ampoules of a flexible material, preferably plastic. The plastic ampoules are separated by a common rupturable partition, one plastic ampoule containing an aqueous solution of an enzyme and a pH indicator while the other ampoule con- tains a substrate suspended in an aqueous medium. When the checking of the handling conditions of a product, i.e. the indication of the temperature as a function of time, is to begin, the rupturable partition is broken by a compressing force being exerted on, for instance, one plastic ampoule. The contents of the plastic ampoules will then communicate with each other such that the contents of the ampoules are mixed and an enzymatic reaction is initiated. The enzymatic reaction proceeds with the formation of a reaction product, such as capronic acid if the substrate is tricaproin and the enzyme is a lipase in dependence on temperature and time. The pH indicator present is intended, by colouring, to indicate the exceeding of a certain amount of reaction product, such as fatty acid. The time-temperature-sensitive enzymatic indicator usually comprises, in addition to the enzymatic composition enclosed in the plastic ampoule, a surrounding package, e.g. made of paper, which is provided with an open- ing through which the colour of the ampoule can be observed. Moreover, the package of the indicator is usually provided with printed formation in connection with the opening. Furthermore, the package is preferably designed as a label, the rear of the package being provided with an adhesive layer with a protective release layer. After removal of the release layer, the indicator can, by means of the adhesive layer, be applied to the product the handling of which is to be checked. In a simpler embodi- ment, the indicator may comprise merely the two plastic ampoules which preferably consist of two rectangular opposed plastic films which are hot-sealed to each other along the edges. One more hot seal transversely of the plastic film and in parallel with the short sides thereof forms the rupturable partition and defines two rectangular spaces between the plastic films, one on each side of the rupturable partition. These two spaces are filled with an enzyme solution and a substrate solution respectively and form the two indicator ampoules. For fixing to the product that is to be indicated, the indicator ampoules can on one side be provided with an adhesive layer and a release layer, the release layer being removed when the indicator is to be fixed to the product.

The above-described type of time-temperature-sensi- tive enzymatic indicators is normally a very satisfactory type of indicator with an indication that in a true manner imitates the time-temperature course of the product, such as a food product, the handling of which is to be checked or monitored. A problem in the context, however, is the activation of the indicator, i.e. the starting of the monitoring function of the indicator by breaking the rupturable partition and mixing the solutions in the ampoule to start the enzymatic reaction of the indicator. For the monitoring and indication of the indicator to be correct and reproducible from indicator to indicator, the activation of the indicator, i.e. the breaking of the rupturable partition and the mixing of the ampoule solu- tions, must occur in a uniform and reproducible manner. Above all the mixing of the ampoule solutions in connection with the activation must be accurate and complete. If the activation is effected manually, for instance, by squeezing an ampoule between one's fingers so that the partition breaks, there is a risk of the mixing of the ampoule solutions being incomplete such that, for instance, originally only part of the substrate solution is contacted with the enzyme solution. This results in the enzymatic reaction being incomplete. Certainly the ampoule solutions can, by diffusion, be further mixed over time so that finally the entire substrate solution is mixed with the enzyme solution, but the originally incomplete mixing means that the indicating procedure as a whole becomes misleading. It is thus most important that the activation of the indicator occurs in a uniform and reproducible manner. Summary of the Invention

The above drawbacks in the activation of indicators comprising two liquid-filled ampoules separated by a rupturable partition are obviated according to the present invention by a simple and reproducible method which accomplishes accurate mixing of the solutions of the indicator ampoules by alternatingly exerting a compress- ing force on the central portion and edge portions of the indicator.

The present invention thus provides a method of activating an indicator which comprises two liquid-filled ampoules separated by a rupturable partition, character- ised by exerting a compressing force for breaking the partition and mixing the liquid in the ampoules by moving pressure-exerting means in a path relative to the indicator, alternatingly along the central portion of the indi^¬ cator and along the edge portions of the indicator. According to the invention, a device is also provided for activation of an indicator which comprises two liquid-filled ampoules separated by a rupturable partition, characterised in that the device comprises a) a carrier for carrying the indicator, b) at least one set of pressure-exerting means with three pressure-exerting means in each set, c) each pressure-exerting means being movable relative to the indicator on the carrier in a path passing the indicator, d) each pressure-exerting means in a set of pres- sure-exerting means having a width which is smaller than the extent of the indicator transversely of the path of the pressure-exerting means relative to the indicator, e) a first pressure-exerting means in each set of pressure-exerting means being arranged to pass in its path the central portion of the indicator while exerting a pressure thereon, f) the second and third pressure-exerting means in each set of pressure-exerting means, which second and third pressure-exerting means are positioned side by side and at a distance from each other, being arranged to pass in their paths the edge portions of the indicator while exerting a pressure thereon.

Further characteristic features and advantages of the invention will appear from the following description and the appended claims.

To ensure a complete mixing of the ampoule solutions during the activation, it is preferred that the above exertion of pressure on the central and edge portions of the indicator is repeated at least once. Accord- ing to a specially preferred embodiment, the exertion of pressure on the central and edge portions of the indi^¬ cator occurs four times. As will be described in more detail below, this can occur by the pressure-exerting means making a reciprocating motion over the indicator. The extent of the exertion of pressure on the central portion and edge portions, respectively, of the indicator may vary, but according to the invention the exertion of pressure on the central portion of the indicator preferably comprises essentially the centrally located or central third of the extent of the indicator transversely of the path of the pressure-exerting means relative to the indicator.

In the same way as it is preferable that the exertion of pressure on the central portion of the indicator comprises essentially the central third of the extent of the indicator transversely of the path of the pressure- exerting means relative to the indicator, the exertion of pressure on the edge portions of the indicator is preferred to comprise essentially the two outer thirds of the extent of the indicator transversely of the path of the pressure-exerting means relative to the indicator. The exertion of pressure along the central portion of the indicator results in the ampoule liquid being compressed and breaking the rupturable partition so that the ampoule solutions will contact each other. During the pressure-exerting motion along the central portion of the indicator, the ampoule solution in the central portion is moved in front of the pressure-exerting means and sideways, thereby achieving a mixing of the ampoule solutions. The exertion of pressure on the central portion of the indicator is then followed by exertion of pressure along the edge portions of the indicator, the ampoule liquids in these portions being moved in front of the pressure-exerting means and sideways, towards the central portion of the indicator, thereby achieving additional mixing of the ampoule liquids. By repeating the exertion of pressure on the central and edge portions of the indicator at least once, the mixing of the ampoule liquids is further improved.

The pressure-exerting means of the device according to the present invention can be of different design and may consist of, for instance, plates or strips having a sufficiently low friction to be able to move freely in the above-mentioned path relative to the indicator. With a view to reducing the friction, the pressure-exerting means can have a surface of polished metal or some other low-friction surface, such as a surface made of poly- tetrafluoroethylene. However, it is particularly prefer- red according to the invention that the pressure-exerting means have the form of rolls which are rotatable and movable relative to the indicator. In a set of rolls comprising a first, a second and a third roll, the first roll can be arranged between and in front of the second and third rolls, the second and third rolls being arranged side by side and at a distance from each other, so that the distance between the second and third rolls corresponds to the width of the first roll.

When the pressure-exerting means are rolls, it is, however, quite particularly preferred in the present invention that all rolls are arranged on a common axis. The above steps comprising alternating exertion of pressure along the central portion of the indicator and along the edge portions of the indicator are achieved in the particularly preferred embodiment of the pressure-exerting means in the form of rolls arranged on a common axis by the indicator being moved relative to the rolls so that the central portion of the indicator is first arranged opposite to the first roll, whereupon, when the first roll has passed the central portion of the indicator, the indicator is moved relative to the rolls so that its edge portions are arranged opposite to the second and the third roll, whereupon these two rolls are moved relative to the indicator along the edge portions thereof while exerting a compressing force.

In this context "relative movement" between the pressure-exerting means and the indicator means that either the pressure-exerting means move while the indicator is immovable, or that the indicator moves while the pressure-exerting means are immovable.

In the above, particularly preferred embodiment in which all rolls are arranged on a common axis, it is besides preferable that all the rolls constitute an integrated cylindrical unit, the individual rolls being formed of ridges of the cylinder. Such a cylindrical unit having rolls in the form of ridges can be easily made of a cylindrical blank by turning the blank in a lathe to form valleys and ridges, i.e. rolls. As material for the pressure-exerting rolls, rubber or a rubber-coated metal is preferred.

As stated above, the indicator normally is of an elongate rectangular shape which comprises two rectangular, liquid-filled ampoules, separated by a rupturable partition. In the presently preferred embodiment, the indicator is arranged with its short side, i.e. with one ampoule directed towards the pressure-exerting means, such that the pressure-exerting means (rolls) during activation move in a path along the long side of the indicator, i.e. over one ampoule, past the partition between the ampoules and over the second ampoule. However it is also possible, although less preferred, to arrange the indicator with its long side directed to the pressure-exerting means (rolls) so that the rolls during activation move along the short side of the indicator. In this case, the first roll moves over the central third of the indicator which comprises the rupturable partition, and then the second and the third roll move over the two remaining thirds of the indicator which comprise the two outer portions of the respective ampoules. Brief Description of the Drawings

To further facilitate the understanding of the pre- sent invention, it will now be described with reference to a preferred embodiment shown in the accompanying Figures 1-4.

Fig. 1 is a side view of the preferred embodiment of the pressure-exerting means when being rolls arranged on a common axis. Fig. 2 is a top plan view of the pressure-exerting means in Fig. 1, certain parts being removed and a sectional view along line II-II in Fig. 1 being shown.

Fig. 3 is a side view of a packing machine which comprises an activating device according to the invention.

Fig. 4 is a top plan view of the packing machine in Fig. 3.

Figs 3 and 4 show a packing machine 1 for packing a product, such as a food product, by placing it from above on a packing table 2. In the embodiment illustrated, the product is packed in a plastic package in such manner that a base sheet 3 of plastic is deep-drawn at a station 4 with the aid of heat and vacuum to form depressions (not shown) in which the product is to be placed. While forming these depressions, also other, smaller depressions (not shown) are made by deep-drawing of the sheet 3. These depressions are intended to accommodate an indicator of the type described above, such as a time-tempe- rature-sensitive enzymatic indicator. The base sheet 3 with the depressions and the product and the indicator arranged therein are fed towards a welding station 5, to which a top sheet 6 from a storage roll 7 is supplied over a guide roll 8 above the base sheet 3 and is welded thereto with the aid of heat and pressure exerted by welding plates (not shown) at the welding station 5. The temperature during welding is generally about 120-140°C and the welding time 1-4 s according to the plastic material used for the base sheet 3 and the top sheet 6. During welding the base sheet 3 and the top sheet 6 form a sealed casing round the product and the indicator. The welding operation is carried out such that the top sheet 6 is welded to the base sheet 3 along the edge portion round the depression containing the product and along the edge portion round the depression containing the indicator. The welding thus results in welded or sealed portions which surround on the one hand the depression containing the product and, on the other hand, the depression containing the indicator. This means that the product as well as the indicator are sealed inside the casing which is formed of the base sheet 3 and the top sheet 6 while at the same time the product and the indicator are separated.

To permit observation of the indicator and its colour from the outside of the package, one of the base sheet 3 and the top sheet 6, or both, preferably at least the top sheet 6, is made of transparent plastic.

After the sealing at the welding station 5, the package comprising the product, the indicator and a surrounding, sealed casing consisting of the base sheet 3 and the top sheet 6 is discharged, and the formed package is separated from the next by means of a cutting device (not shown) .

In connection with the welding at the welding station 5, the atmosphere in the package is preferably removed and replaced by vacuum or a protective gas, which can be selected among, for instance, nitrogen and/or carbon dioxide, possibly in combination with oxygen.

By integrating the indicator with the package in the manner described above, it is not necessary for the indicator to be an ampoule containing an indicator solution and being provided with an external label with text and an adhesive layer with a release foil on the underside. Instead it is sufficient for the indicator which is integrated with the package to consist of an indicator ampoule, preferably made of plastic, containing an indi- cator solution, preferably an enzymatic indicator solution comprising an enzyme and an enzymatic substrate. The label with the printed information and the adhesive layer with the release foil can thus be omitted from the indicator. This entails a considerable simplification and saving in cost.

The indicator which is arranged in and integrated with the package is inserted in the associated depression in the package by placing it from above on the table 2. The indicator which is placed in the package is activated. The activation of the indicator and the placing thereof in the package will now be described in more detail.

As shown in Figs 1-2, the pressure-exerting means 9 are in the form of a cylinder, on which rolls 10-15 in the form of projecting peripheral ridges are formed. The rolls 10-15 of the cylinder 9 have a common axis 16. The cylinder 9 is preferably made of rubber 17 on a core of metal 18.

As is also shown in Fig. 2, the indicator has the above-described form of two rectangular, liquid-filled ampoules 19, 20 separated by a rupturable partition 21, which is indicated by dashed lines. The two liquid-filled ampoules 19, 20 are otherwise defined by welded edge portions 22. Of the two ampoules 19, 21, one contains an enzyme solution while the other contains a substrate solution. Moreover, one of the ampoule solutions, or both, contains a pH indicator for generating a colour change.

Fig. 2 shows how an indicator is arranged in front of a roll 10, which when moving over the indicator (to the left in Fig. 2) compresses the central part of the indicator and causes the rupturable partition 21 to rupture so that the solutions in the ampoules 19 and 20 are contacted with each other and are mixed with each other. When the roll 10 has moved over the indicator once (to the left in Fig. 2) , it is then moved back (to the right in Fig. 2) for one more compression of the central third of the indicator. Then the indicator is supplied sideways relative to the cylinder 9 (upwards in Fig. 2) so as to be located in front of the other two rolls 11, 12 in a set of rolls. As appears from Fig. 2, each roll has a width which corresponds to approximately one third of the indicator, the rolls 11 and 12 being arranged adjacent to the two outer thirds of the indicator. The rolls 11, 12 are then moved over the indicator (to the left in Fig. 2) , the two outermost thirds of the indicator being compressed such that the ampoule solutions are pressed towards the centre of the indicator. The rolls 11 and 12 are then moved back (to the right in Fig. 2) during renewed compression of the outer portions of the indicator. By the shown cylinder 9 comprising a total of 6 rolls 10-15, corresponding to two sets of rolls with three rolls in each set, the above-described activating procedure involving a reciprocating motion of each roll 10-15 means that each central and edge portion of the indicator is exposed to a compressive force a total of four times during the activating procedure. This entails an extremely intense and accurate mixing of the ampoule solutions, i.e. the activation of the indicator is complete.

The activating procedure described above in connection with Figs 1-2 is used in the activating device in Figs 3-4 of the drawings. An activating device generally designated 22 is mounted on the packing machine 1. The activating device comprises a frame 23 having a shaft 24 for a roll 25 with indicators. As indicated in Figs 3-4, the indicators 26 are arranged on a release layer 27, and each indicator is separately arranged on the release layer with its long side arranged essentially perpendicular to the feeding direction of the release layer. The indicator roll 25 is unwound over a resilient guide bar 28 to an activating station 29, where the indicator is arranged on a carrier 30 and exposed to a compressive force applied by an activating cylinder 9 with activating rolls, in the manner as described above. The activating cylinder 9 then moves back and forth over the indicators 26 with the release layer 27 which are arranged on the carrier 30. After each reciprocating activating motion of the cylinder 9, the indicators are advanced step by step for the next activating operation. After having undergone activation at the activating station 29 in the manner described above, the indicators are discharged from the activating station and supplied to an application station 31. At the application station, a turnable application head 32 (see the encircled partial picture in Fig. 3) engages the indicators and removes these one by one from the release layer 27 by means of suction cups 33. Subsequently the release layer 27 is removed from the application station 31 by means of feed rollers 34, 35.

The turnable application head 32 and the indicators 26 fixed thereto by suction are then fed by means of a motor 36 sideways over the machine 1 in the transverse direction of the table 2. The application equipment is then programmed by means of programming equipment (not shown) in such manner that, when the application head 32 is located above and opposite to a depression in the base sheet 3 which is intended for an indicator, the lateral movement of the application equipment is stopped and the negative pressure in the suction cups 33 for the indicator which is positioned above the depression is equalised such that the indicator is released and arranged in the depression. Subsequently the application of the next indicator is carried out correspondingly.

The activation of an indicator according to the invention has been described above with reference to a especially preferred embodiment of an activating device according to the invention in connection with a special packing machine, but it will be appreciated that the invention is not limited thereto, and that the activating method and the activating device according to the inven- tion can be varied in many ways within the scope of the appended claims, and that the inventive activating device can be combined with different types of packing machines.

Claims

1. A method of activating an indicator (26) compris- ing two liquid-filled ampoules (19, 20) separated by a rupturable partition (21) , c h a r a c t e r i s e d by exerting a compressive force for breaking the partition (21) and mixing the liquid in the ampoules (19, 20) by moving pressure-exerting means (10-15) in a path relative to the indicator, alternatingly along the central portion of the indicator and along the edge portions of the indicator.

2. A method as claimed in claim 1, c h a r a c t e r i s e d by repeating the exertion of pressure on the central and edge portions of the indicator at least once .

3. A method as claimed in claim 1 or 2, c h a r a c t e r i s e d in that the exertion of pressure on the central portion of the indicator comprises essentially the central third of the extent of the indicator transversely of the path of the pressure-exerting means relative to the indicator.

4. A method as claimed in any one of claims 1-3, c h a r a c t e r i s e d in that the exertion of pressure on the edge portions of the indicator comprises essentially the two outer thirds of the extent of the indicator transversely of the path of the pressure-exerting means relative to the indicator.

5. A device for activating an indicator (26) com- prising two liquid-filled ampoules (19, 20) separated by a rupturable partition (21) , c h a r a c t e r i s e d in that the device comprises a) a carrier for carrying the indicator (26) , b) at least one set of pressure-exerting means (10-15) with three pressure-exerting means (10, 11,

12; 13, 14, 15) in each set, c) each pressure-exerting means being movable relative to the indicator (26) on the carrier (30) in a path passing the indicator, d) each pressure-exerting means in a set of pres- sure-exerting means (10-12; 13-15) having a width which is smaller than the extent of the indicator transversely of the path of the pressure-exerting means relative to the indicator, e) a first pressure-exerting means (10; 13) in each set of pressure-exerting means (10-12; 13-15) being arranged to pass in its path the central portion of the indicator (26) while exerting a pressure thereon, f) the second and third pressure-exerting means (11, 12; 14, 15) in each set of pressure-exerting means, which second and third pressure-exerting means are positioned side by side and at a distance from each other, being arranged to pass in their paths the edge portions of the indicator while exerting a pressure thereon.

6. A device as claimed in claim 5, c h a r a c - t e r i s e d in that each pressure-exerting means

(10-15) has a width essentially corresponding to one third of the extent of the indicator (26) transversely of the path of the pressure-exerting means relative to the indicator.

7. A device as claimed in claim 5 or 6, c h a r a c t e r i s e d in that the second and third pressure- exerting means (10, 12; 14, 15) in each set of pressure- exerting means are arranged at a distance from each other which essentially corresponds to one third of the extent of the indicator (26) transversely of the path of the pressure-extending means relative to the indicator.

8. A device as claimed in any one of claims 5-7, c h a r a c t e r i s e d in that the pressure-exerting means (10-15) are rolls.

9. A device as claimed in claim 8, c h a r a c t e r i s e d in that all rolls are arranged on a common axis (16) .

10. A device as claimed in claim 8 or 9, ch a r a c t e r i s e d in that all rolls (10-15) constitute an integrated cylindrical unit (9) , the individual rolls being formed of ridges of the cylinder (9) .