WO2008148964A2 - Indicator indicating that a temperature threshold has been crossed - Google Patents

Indicator indicating that a temperature threshold has been crossed Download PDF

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Publication number
WO2008148964A2
WO2008148964A2 PCT/FR2008/050716 FR2008050716W WO2008148964A2 WO 2008148964 A2 WO2008148964 A2 WO 2008148964A2 FR 2008050716 W FR2008050716 W FR 2008050716W WO 2008148964 A2 WO2008148964 A2 WO 2008148964A2
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WO
WIPO (PCT)
Prior art keywords
state
compound
temperature
colorless
colored
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Application number
PCT/FR2008/050716
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French (fr)
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WO2008148964A3 (en
Inventor
Renaud Vaillant
Catherine Bonaiti-Fleurie
Frédéric Chaput
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Sa Cryolog
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Publication of WO2008148964A2 publication Critical patent/WO2008148964A2/en
Publication of WO2008148964A3 publication Critical patent/WO2008148964A3/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/12—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in colour, translucency or reflectance

Definitions

  • the present invention relates to a control of crossing a temperature threshold, downward and / or upward, using a reversible thermochromic compound.
  • Such cookies, or indicators are useful for monitoring any perishable products or substances that need to be stored under specified temperature conditions. It is primarily concerned with the agri-food sector, especially for all fresh or frozen products, but also the pharmaceutical and medical fields, some drugs to be kept at a given temperature, as well as some vaccines, blood bags ...
  • thermochromic compound having a hysteresis curve for the variation of the color as a function of temperature
  • thermochromic compounds which have a memory effect of their coloring over a greater or lesser temperature range after they have undergone a color change.
  • FIG. 1 shows the ideal evolution of the coloration of such a compound as a function of the temperature and the thermal history of this compound.
  • the compound can take two distinct states of coloration (I and II) and that, depending on the direction of change of state (increase or decrease in temperature), the change is made at temperatures T hau t e and T ba sse are also distinct or even far apart (the difference ⁇ T can reach sixty degrees).
  • This difference between the high and low state change temperatures characterizes the width of the hysteresis cycle of this thermochromic compound, and it is this large width that makes it possible to use such a compound to produce a threshold crossing indicator. Indeed, if one places oneself under certain conditions, for example in a restricted temperature range comprising only one of the two change of state temperature of the compound, then any change of state of the compound in this irreversible interval.
  • the reversibility of the color change of the compound over an unbounded temperature range is potentially irreversible over some bounded temperature ranges. If one refers again to Figure 1, for example shows that if the temperature is less than T hau t e and the system is in state I, then any intervening change in color in this interval will necessarily : i) following a temperature drop, ii) from state I to state II, iii) irreversible, since the compound will always remain below the high change temperature T hau t e , and therefore can not return in the state I. In practice, the compound will therefore be chosen so that its low state change temperature is close to or equal to / at the threshold temperature which it is desired to monitor the crossing.
  • thermochromic compounds however, has a significant disadvantage: the reversibility of the change of state of these compounds. Indeed, even if this one is "circumvented” by the use which is made of these compounds, this one remains very real and raises problems of confidence and thus of security of the witnesses.
  • FIG. 2 represents the change of state cycle of a compound having change temperatures of 0 ° C. and 30 ° C. respectively. It can be used to produce a lower threshold crossing control, for example to monitor that vaccines do not cross the temperature of 0 0 C. Indeed, some vaccines must be kept at a temperature close to 5 ° C, and their storage temperature should not fall below 0 0 C, otherwise the vaccine may be damaged. If such a scenario occurs, this would involve a change in the color of the compound (passage from state I, colorless, to state II, very colored) which would be visible and would indicate to the persons concerned that the vaccine is damaged. However, it can be seen in FIG.
  • the storage temperature rises above 30 ° C. (ie the high change temperature of the thermochromic compound), then it is modified again the color of the witness (who returns to his state I). If the temperature then stabilizes at its nominal value of about 5 ° C, then the control shows no coloration.
  • the information provided by the witness is therefore erroneous because it is in its initial state while the vaccine has successively reached two critical temperatures, 0 0 C and 30 0 C: although the witness displays the contrary information, the vaccine is in unusable reality.
  • the object of the invention is to overcome the drawbacks described above by proposing a temperature threshold crossing control using a reversible thermochromic compound, the information of which is provided that can not be tampered with, thereby guaranteeing complete safety as regards the good preservation of the products concerned.
  • the invention relates to a temperature crossing indicator, making it possible to establish whether a product, in particular a perishable product, has passed at least one of two threshold temperature values forming the lower and upper ends of a range of surveillance, the witness comprising: a first reversible thermochromic compound having, depending on the temperature and its history of variations, either a colored state or a colorless or slightly colored state, the transition from one state to another occurring at two different temperatures depending on the temperature varies in increasing or decreasing
  • thermochromic compound having, depending on the temperature and its history of variations, either a colored state or a colorless or slightly colored state,
  • the first compound being in an initial state, at a temperature comprised between the two threshold values, colored or colorless, a change of state occurring when one of the two threshold values is crossed,
  • the second compound being in an initial state, at a temperature between the two threshold values, colored or colorless, a change of state occurring during the crossing of the second threshold value, in the opposite direction to the crossing of the first threshold value; , before the first compound returns to its initial state, so that at least one of the two compounds is no longer in its initial state when one of the two threshold temperatures has been crossed, temporarily or not.
  • any accidental discoloration of the first compound occurring after a coloration following the crossing of a threshold temperature is surely compensated by the prior or simultaneous coloring of the second compound.
  • the witness according to the invention thus has a total reliability as to the information it provides on the good or bad conservation of the monitored product. Indeed, the control will be definitively colored as soon as the storage temperature of the product has crossed, even temporarily, one of the two temperatures forming the ends of the monitoring range.
  • the color change of the second thermochromic compound is irreversible.
  • the change of state temperature of the second compound is:
  • the second compound is a reversible thermochromic compound.
  • the initial state of the first and second compounds is the colorless state.
  • the first and second compounds are such that: the temperature of transition from the colored state to the colorless state of the second compound is less than or equal to the transition temperature from the colorless state to the colored state of the first compound.
  • the temperature of transition from the colorless state to the colored state of the second compound is between the two change-of-state temperatures of the first compound.
  • the initial state of the first and second compounds is the colored state.
  • the first and second compounds are such that: the temperature of transition from the colorless state to the colored state of the second compound is greater than the transition temperature from the colored state to the colorless state of the first compound; compound,
  • the temperature of transition from the colored state to the colorless state of the second compound is between the two change of state temperatures of the first compound.
  • the transition temperatures from the colorless state to the colored state and from the colored state to the colorless state of the second compound respectively coincide with the transition temperatures from the colored state to the colorless state. and passing from the colorless state to the colored state of the first compound.
  • the second compound comprises a thermochromic ink and / or a spin transition compound.
  • the first compound comprises a thermochromic ink and / or a spin transition compound.
  • the first and second compounds are identical and packaged during manufacture of the control each in a different initial staining state, one being colorless while the other is stained.
  • the first and second compounds are arranged to form a pattern.
  • the first compound passes from the colorless state to the colored state as the temperature increases.
  • the first compound passes from the colorless state to the colored state as the temperature varies in a decreasing manner.
  • the control comprises two films of which at least one is partially transparent, the two films being hermetically assembled to contain the first and the second compounds.
  • the first and second compounds are packaged in two separate compartments.
  • FIGS. 1 and 2 already described, represent the coloring cycle as a function of the temperature of a reversible thermochromic compound
  • FIG. 3 represents the spin state change cycle as a function of the temperature of a spin transition compound
  • FIG. 4 represents an example of use of a control according to the invention
  • FIG. 5 represents the color variation of a control according to the invention when the change of state of the second thermochromic compound is irreversible
  • FIGS. 6, 7 and 8 represent different combinations of the first and second compounds when the change of state of the second compound is reversible
  • FIG. 9 represents an embodiment of the invention in which two identical compounds are used in different starting states.
  • the control 10 is in the form of a colorless label, in the self-adhesive example, intended to be affixed to each product to be monitored.
  • the control 10 comprises a first reversible thermochromic compound A and a second thermochromic compound B.
  • a thermochromic ink can be used, for example as those described in the documents EP1657073 and US5,558,699.
  • the coloring of compound B must take place at a predetermined temperature, so as to be able to compensate for a possible change to the colorless state of compound A if the successive temperature variations have had the consequence that after crossing the temperature threshold, compound A described a complete cycle of staining / discoloration.
  • the examples described below show that in addition to providing absolute security to the control, the presence of a second thermochromic compound B makes it possible to produce a control which provides both downward and upward monitoring, allowing ensure that the temperature has remained within a given range or monitoring range.
  • the compounds A and B are trapped in two separate compartments of the control 10, which thus has two viewing windows juxtaposed.
  • the reading of the control is very simple: since the initial state of the two compounds A and B is the colorless state, there has been a lack of conservation since at least the one of the windows displays a color.
  • the compounds A and B can be combined in a single package, as long as their mixing is possible without affecting the operation of the control.
  • FIGS. 5 and 6 show that compound A is identical to the compound used in the example of FIG. FIG. 2: it moves from the colorless or slightly colored state (state I A ) to the colored state (state II A ) at a temperature T ba sse-A close to zero degrees Celsius, thus making it possible to "mark" the vaccine if it has been stored at a temperature below 0 ° C, even temporarily.
  • the control 10 also comprises a second thermochromic compound B, reversible or not.
  • FIG. 5 describes an embodiment of the invention where the second thermochromic compound B has an irreversible state change.
  • Compound B is chosen so that its temperature T hau t e -B of transition from the colorless state (state I B ) to the colored state (state II B ) is less than or equal to the temperature of inverse passage T hau t e -A compound A.
  • T hau t e -B of transition from the colorless state (state I B ) to the colored state (state II B ) is less than or equal to the temperature of inverse passage T hau t e -A compound A.
  • the monitoring range of the indicator 10 is defined by the temperatures T ba sse-A and T hau te-B-
  • Figures 6, 7 and 8 show different variants of an embodiment of the invention wherein compound B is a reversible thermochromic compound.
  • compound B has two change temperatures T low eB and T high -B, and the different variants presented below depend on the relative values of these temperatures with respect to the change of state temperatures of the first compound A.
  • FIG. 6 shows a variant in which the low TB and T high -B T-state change temperatures of the second B compound are such that each change of state of the compound B coincides with the inverse change of the compound A.
  • T basS eB is equal to T low- A (or very close to T low- A)
  • T hau t e- B is equal to T hau t e- A (or very close to T hau t e - A) -
  • the control 10 works in the same way as in Figure 5, except that when the temperature exceeds T high- B and compound B becomes colored (the compound A becoming colorless), the coloring of compound B is not definitive. Indeed, if the temperature is brought down below T low eB, then the compound B becomes colorless again.
  • the security provided by the control according to the invention is always complete because, at the same time, compound A becomes colored again.
  • the indicator will be colored if one of status change Lower temperatures T A or T B Upper, the compound A, has been crossed.
  • T A or T B Upper, the compound A are the two change temperatures state of the first compound A which define the monitoring range of the control 10.
  • FIG. 7 represents a variant in which the second compound B is such that its change of state temperatures T ba sse-B and T high - B are respectively lower than the inverse change temperature of the compound A.
  • T ba sse-B is less than or equal to Tbasse-A
  • T hau te-B is less than or equal T hau t e -A-
  • the monitoring range, narrower is defined by the Bass T eA and Th temperatures ute-B- witness however, works in the same way: the initial state of the two compounds A and B is the colorless state (state 1).
  • the security of the witness is therefore absolute: as soon as at least one of the temperature limits of the monitoring range will be crossed, even temporarily and for a short period of time, then at least one of the compounds A or B will be colored.
  • the variant of FIG. 7 further shows that the control can be adapted in a simple manner by combining thermochromic compounds and their change of state temperatures in order to precisely define the desired monitoring page.
  • a third variant is shown in Figure 8.
  • the initial state of the compounds A and B is in this example the colored state.
  • the The temperature of the change of state T ba sse-B and T hau t e -B of the second compound B are respectively greater than each inverse change temperature of the compound A.
  • T ba sse-B is greater than or equal to Tbasse-A and T hau te-B is greater than or equal to T ue t e -A- It is therefore the temperatures T low eB and T high -A which define here the monitoring range.
  • control according to the invention makes it possible to monitor the exceeding of a temperature threshold upwards or downwards with total security as to the information provided by the witness: no falsification or accidentally erroneous information is possible as for the indicators of the prior art.
  • thermochromic compounds used comprises a spin-transition compound, for example those described in document FR2755696.
  • Figure 3 shows an example of a hysteresis loop of spin transition compounds. On the ordinate, a magnitude has been reported which reflects the spin state and not the color state; the state of coloration exhibits an inverted hysteresis cycle comparable to that represented in FIG. 1.
  • These compounds exhibit a transition of spin states, between a so-called low spin state (LS) and a so-called high spin state (HS) which is induced thermally, and that is accompanied by electronic configuration change and structural modifications of the molecules causing an abrupt change in the absorption spectrum of the molecules, and therefore the color of the compounds.
  • LS low spin state
  • HS high spin state
  • thermochromic compounds A and A ' of the type represented in FIG. 1, are used, but brought during the manufacturing each in a different initial state from each other. .
  • the compound A will be in the initial state I, while the compound A 'will be in the initial state II.
  • the compounds A and A ' are packaged in two separate compartments, as for the example of FIG.
  • the window of the compartment containing A does not display coloring
  • the second window that of the compartment containing A '
  • the two windows thus indicate states of opposite colorations.
  • the control 10 is then affixed to a product to be monitored.
  • the operation of the control 10 is then as follows: i) if the temperature thereof exceeds T hau t e -A, then the compound A 'will go from the state II to the I state, while the compound A does not change its state (state I).
  • the two windows will then indicate the same coloring state, in this case the colorless state.
  • ii) if, on the contrary, the temperature of the monitored product falls below T ba sse-A, then the compound A goes from state I to state
  • the compounds A and A ' are trapped in the same package, and these are packaged during manufacture in such a way that their difference in color forms a pattern, in the example in the shape of a cross.
  • the control of FIG. 9 can be obtained by using compound A, deposited in its II state (colored) at ambient temperature, and by heating the part intended to form the pattern locally, which then becomes transparent.
  • the indicator 10 Before use, the indicator 10 therefore has a single viewing window displaying a pattern. So we see that if the temperature exceeds the temperature T hau t e -A, the portion of the control in the colored state will pass to the colorless state, the surface of the control 10 will be completely colorless. Conversely, if the temperature exceeds the temperature T ba sse-A, then the portion of the control in the colorless state will change to the colored state, the witness then being fully colored. The witness of FIG. 9 will therefore indicate a defect of conservation since it no longer makes it possible to discern any motive, whether the state indicated is colorless or colored.

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Abstract

The invention relates to a temperature crossing indicator making it possible to establish whether a product, particularly a perishable product, has crossed a threshold temperature value, in an increasing or decreasing direction manner, the indicator comprising: a first reversible thermochromic compound (A) having, depending on the temperature and its history of variations, either a coloured state (IU) or a colourless or slightly coloured state (U), the transition from one state to the other occurring at two distinct temperatures depending on whether the temperature varies in an increasing or decreasing manner, a second thermochromic compound (B) having, depending on the temperature and its history of variations, either a coloured state (HB) or a colourless or slightly coloured state (IB), the second compound being such that its transition to the coloured state (HB) compensates for the transition to the colourless state (U) of the first compound.

Description

TÉMOIN DE FRANCHISSEMENT D'UN SEUIL DE TEMPÉRATURE TEMPERATURE THRESHOLD TEMPERATURE THRESHOLD
La présente invention est relative à un témoin de franchissement d'un seuil de température, à la baisse et/ou à la hausse, utilisant un composé thermochrome réversible.The present invention relates to a control of crossing a temperature threshold, downward and / or upward, using a reversible thermochromic compound.
De tels témoins, ou indicateurs, sont utiles pour surveiller tous produits ou substances périssables qui doivent être conservées dans des conditions de température spécifiées. Est concerné en premier lieu le domaine agroalimentaire, notamment pour tous les produits frais ou surgelés, mais également les domaines pharmaceutique et médical, certains médicaments devant être conservés à une température donnée, de même que certains vaccins, poches de sang...Such cookies, or indicators, are useful for monitoring any perishable products or substances that need to be stored under specified temperature conditions. It is primarily concerned with the agri-food sector, especially for all fresh or frozen products, but also the pharmaceutical and medical fields, some drugs to be kept at a given temperature, as well as some vaccines, blood bags ...
Il est connu d'utiliser un composé thermochrome réversible, présentant une courbe d'hystérésis pour la variation de la coloration en fonction de la température, pour réaliser un témoin de franchissement de seuil de température. Ces témoins utilisent les propriétés de certains composés thermochromes, qui présentent un effet mémoire de leur coloration sur un intervalle de température plus ou moins grand après qu'ils aient subi un changement de couleur. La figure 1 montre l'évolution idéale de la coloration d'un tel composé en fonction de la température et de l'historique thermique de ce composé. On peut voir sur cette figure que le composé peut prendre deux états de coloration bien distincts (I et II) et que, selon le sens de changement d'état (augmentation ou diminution de la température), le changement se fait à des températures Thaute et Tbasse également bien distinctes, voire très éloignées (la différence ΔT pouvant atteindre une soixantaine de degrés). Cette différence entre les températures de changement d'état haute et basse caractérise la largeur du cycle d'hystérésis de ce composé thermochrome, et c'est cette largeur importante qui permet d'utiliser un tel composé pour réaliser un témoin de franchissement de seuil. En effet, si l'on se place dans certaines conditions, par exemple dans un intervalle de température restreint ne comprenant qu'une seule des deux températures de changement d'état du composé, on rend alors tout changement d'état du composé dans cet intervalle irréversible. En d'autres termes, la réversibilité du changement de coloration du composé sur un intervalle de température non borné est potentiellement irréversible sur certains intervalles de température bornés. Si l'on se réfère de nouveau à la figure 1 , on voit par exemple que si la température reste inférieure à Thaute et que le système est dans l'état I, alors tout changement de coloration intervenant dans cet intervalle sera nécessairement : i) consécutif à une baisse de température, ii) de l'état I vers l'état II, iii) irréversible, puisque le composé restera toujours en dessous de la température de changement haute Thaute, et ne pourra donc revenir à l'état I. En pratique, le composé sera donc choisi de manière à ce que sa température de changement d'état basse soit proche ou égale de/à la température seuil dont on souhaite surveiller le franchissement.It is known to use a reversible thermochromic compound, having a hysteresis curve for the variation of the color as a function of temperature, to produce a temperature threshold crossing control. These controls use the properties of certain thermochromic compounds, which have a memory effect of their coloring over a greater or lesser temperature range after they have undergone a color change. FIG. 1 shows the ideal evolution of the coloration of such a compound as a function of the temperature and the thermal history of this compound. It can be seen in this figure that the compound can take two distinct states of coloration (I and II) and that, depending on the direction of change of state (increase or decrease in temperature), the change is made at temperatures T hau t e and T ba sse are also distinct or even far apart (the difference ΔT can reach sixty degrees). This difference between the high and low state change temperatures characterizes the width of the hysteresis cycle of this thermochromic compound, and it is this large width that makes it possible to use such a compound to produce a threshold crossing indicator. Indeed, if one places oneself under certain conditions, for example in a restricted temperature range comprising only one of the two change of state temperature of the compound, then any change of state of the compound in this irreversible interval. In other words, the reversibility of the color change of the compound over an unbounded temperature range is potentially irreversible over some bounded temperature ranges. If one refers again to Figure 1, for example shows that if the temperature is less than T hau t e and the system is in state I, then any intervening change in color in this interval will necessarily : i) following a temperature drop, ii) from state I to state II, iii) irreversible, since the compound will always remain below the high change temperature T hau t e , and therefore can not return in the state I. In practice, the compound will therefore be chosen so that its low state change temperature is close to or equal to / at the threshold temperature which it is desired to monitor the crossing.
Ces trois points sont valables, mutatis mutandis, si l'on se place dans un intervalle de température comprenant Thaute et ne comprenant pas Tbasse, ce qui permet alors d'utiliser le composé comme témoin de franchissement de seuil à la hausse.These three points are valid, mutatis mutandis, if one places oneself in a temperature range comprising Thaute and not including Tbasse, which then makes it possible to use the compound as a threshold crossing control on the rise.
Une telle utilisation de composés thermochromes présente cependant un inconvénient de taille : la réversibilité du changement d'état de ces composés. En effet, même si celle-ci est « contournée » par l'utilisation qui est faite de ces composés, celle-ci reste bien réelle et pose des problèmes de confiance et donc de sécurité des témoins.Such use of thermochromic compounds, however, has a significant disadvantage: the reversibility of the change of state of these compounds. Indeed, even if this one is "circumvented" by the use which is made of these compounds, this one remains very real and raises problems of confidence and thus of security of the witnesses.
Ainsi, la figure 2 représente le cycle de changement d'état d'un composé présentant des températures de changement respectivement de 00C et 300C. Il peut être utilisé pour réaliser un témoin de franchissement de seuil à la baisse, par exemple pour surveiller que des vaccins ne franchissent pas la température de 00C. En effet, certains vaccins doivent être conservés à une température proche de 5°C, et leur température de conservation ne doit pas descendre en dessous de 00C, sous peine d'endommager le vaccin. Si un tel scénario se produisait, cela impliquerait un changement de coloration du composé (passage de l'état I, incolore, à l'état II, très coloré) qui serait donc visible et indiquerait aux personnes concernées que le vaccin est endommagé. Cependant, on voit sur la figure 2 que, si après être descendu en dessous de 00C, la température de conservation remonte au-dessus de 300C (i.e. la température de changement haute du composé thermochrome), alors on modifie à nouveau la couleur du témoin (qui revient à son état I). Si la température se stabilise ensuite à sa valeur nominale d'environ 5°C, alors le témoin ne présente aucune coloration. L'information fournie par le témoin est donc erronée car il est dans son état initial alors que le vaccin a atteint successivement deux températures critiques, 00C et 300C : bien que le témoin affiche l'information contraire, le vaccin est en réalité inutilisable.Thus, FIG. 2 represents the change of state cycle of a compound having change temperatures of 0 ° C. and 30 ° C. respectively. It can be used to produce a lower threshold crossing control, for example to monitor that vaccines do not cross the temperature of 0 0 C. Indeed, some vaccines must be kept at a temperature close to 5 ° C, and their storage temperature should not fall below 0 0 C, otherwise the vaccine may be damaged. If such a scenario occurs, this would involve a change in the color of the compound (passage from state I, colorless, to state II, very colored) which would be visible and would indicate to the persons concerned that the vaccine is damaged. However, it can be seen in FIG. 2 that, if, after being lowered below 0 ° C., the storage temperature rises above 30 ° C. (ie the high change temperature of the thermochromic compound), then it is modified again the color of the witness (who returns to his state I). If the temperature then stabilizes at its nominal value of about 5 ° C, then the control shows no coloration. The information provided by the witness is therefore erroneous because it is in its initial state while the vaccine has successively reached two critical temperatures, 0 0 C and 30 0 C: although the witness displays the contrary information, the vaccine is in unusable reality.
Il se pose donc un sérieux problème de confiance quant à l'utilisation de ce type de témoins, d'autant plus que le scénario décrit plus haut peut se produire non seulement accidentellement, à cause de dysfonctionnements dans le système de conservation, mais également de manière volontaire et frauduleuse. En effet, il faut envisager qu'une personne responsable du stockage de produits qui auraient été par erreur soumis à des températures interdites puisse volontairement chauffer (ou refroidir selon le type de témoin) les échantillons afin de faire disparaître la coloration qui aurait indiqué un défaut de conservation, avec pour conséquence la perte du stock. L'invention a pour objet de remédier aux inconvénients décrits ci- dessus, en proposant un témoin de franchissement de seuil de température utilisant un composé thermochrome réversible, dont l'information fournie soit infalsifiable, garantissant ainsi une sécurité totale quant à la bonne conservation des produits concernés. Ainsi, l'invention concerne un témoin de franchissement de température, permettant d'établir si un produit, notamment un produit périssable, a franchi au moins l'une de deux valeurs de température seuil formant les extrémités inférieure et supérieure d'une plage de surveillance, le témoin comprenant : - un premier composé thermochrome réversible, présentant en fonction de la température et de son historique de variations soit un état coloré soit un état incolore ou peu coloré, le passage d'un état à l'autre intervenant à deux températures distinctes selon que la température varie de manière croissante ou décroissante,There is therefore a serious problem of trust regarding the use of this type of witness, especially since the scenario described above can occur not only accidentally, because of dysfunctions in the conservation system, but also voluntarily and fraudulently. Indeed, it is necessary to consider that a person responsible for the storage of products which would have been mistakenly subjected to forbidden temperatures can voluntarily heat (or cool according to the type of witness) the samples in order to make disappear the coloration which would have indicated a defect of conservation, with consequent loss of stock. The object of the invention is to overcome the drawbacks described above by proposing a temperature threshold crossing control using a reversible thermochromic compound, the information of which is provided that can not be tampered with, thereby guaranteeing complete safety as regards the good preservation of the products concerned. Thus, the invention relates to a temperature crossing indicator, making it possible to establish whether a product, in particular a perishable product, has passed at least one of two threshold temperature values forming the lower and upper ends of a range of surveillance, the witness comprising: a first reversible thermochromic compound having, depending on the temperature and its history of variations, either a colored state or a colorless or slightly colored state, the transition from one state to another occurring at two different temperatures depending on the temperature varies in increasing or decreasing
- un second composé thermochrome, présentant en fonction de la température et de son historique de variations soit un état coloré soit un état incolore ou peu coloré,a second thermochromic compound having, depending on the temperature and its history of variations, either a colored state or a colorless or slightly colored state,
- le premier composé étant dans un état initial, à une température comprise ente les deux valeurs seuil, coloré ou incolore, un changement d'état intervenant lors du franchissement d'une des deux valeurs seuil,the first compound being in an initial state, at a temperature comprised between the two threshold values, colored or colorless, a change of state occurring when one of the two threshold values is crossed,
- le second composé étant dans un état initial, à une température comprise entre les deux valeurs seuil, coloré ou incolore, un changement d'état intervenant lors du franchissement de la deuxième valeur seuil, dans le sens inverse du franchissement de la première valeur seuil, avant que le premier composé ne revienne à son état initial, de sorte qu'au moins l'un des deux composés n'est plus dans son état initial dès lors qu'une des deux températures seuil a été franchie, temporairement ou non. Ainsi, grâce à l'invention, toute décoloration accidentelle du premier composé survenant après une coloration consécutive au franchissement d'une température seuil est compensée de manière sure par la coloration préalable ou simultanée du second composé. Le témoin selon l'invention présente donc une fiabilité totale quant à l'information qu'il fournit sur la bonne ou mauvaise conservation du produit surveillé. En effet, le témoin sera coloré de manière définitive dès lors que la température de conservation du produit a franchi, même temporairement, l'une des deux températures formant les extrémités de la plage de surveillance.the second compound being in an initial state, at a temperature between the two threshold values, colored or colorless, a change of state occurring during the crossing of the second threshold value, in the opposite direction to the crossing of the first threshold value; , before the first compound returns to its initial state, so that at least one of the two compounds is no longer in its initial state when one of the two threshold temperatures has been crossed, temporarily or not. Thus, thanks to the invention, any accidental discoloration of the first compound occurring after a coloration following the crossing of a threshold temperature is surely compensated by the prior or simultaneous coloring of the second compound. The witness according to the invention thus has a total reliability as to the information it provides on the good or bad conservation of the monitored product. Indeed, the control will be definitively colored as soon as the storage temperature of the product has crossed, even temporarily, one of the two temperatures forming the ends of the monitoring range.
Dans une réalisation, le changement de coloration du second composé thermochrome est irréversible.In one embodiment, the color change of the second thermochromic compound is irreversible.
Dans une réalisation, la température de changement d'état du second composé est :In one embodiment, the change of state temperature of the second compound is:
- inférieure ou égale à la température de passage de l'état coloré à l'état incolore du premier composé si ce passage s'effectue suivant une variation de température croissante ; - supérieure ou égale à la température de passage de l'état coloré à l'état incolore du premier composé si ce passage s'effectue suivant une variation de température décroissante.- less than or equal to the temperature of transition from the colored state to the colorless state of the first compound if this passage takes place according to an increasing temperature variation; - greater than or equal to the temperature of transition from the colored state to the colorless state of the first compound if this passage takes place according to a decreasing temperature variation.
Dans une réalisation, le second composé est un composé thermochrome réversible.In one embodiment, the second compound is a reversible thermochromic compound.
Dans une réalisation, l'état initial des premier et second composés, est l'état incolore.In one embodiment, the initial state of the first and second compounds is the colorless state.
Dans une réalisation, les premier et second composés sont tels que : - la température de passage de l'état coloré à l'état incolore du second composé est inférieure ou égale à la température de passage de l'état incolore vers l'état coloré du premier composé.In one embodiment, the first and second compounds are such that: the temperature of transition from the colored state to the colorless state of the second compound is less than or equal to the transition temperature from the colorless state to the colored state of the first compound.
- la température de passage de l'état incolore à l'état coloré du second composé est comprise entre les deux températures de changement d'état du premier composé.the temperature of transition from the colorless state to the colored state of the second compound is between the two change-of-state temperatures of the first compound.
Dans une réalisation, l'état initial des premier et second composés, est l'état coloré.In one embodiment, the initial state of the first and second compounds is the colored state.
Dans une réalisation, les premier et second composés sont tels que : - la température de passage de l'état incolore à l'état coloré du second composé est supérieure à la température de passage de l'état coloré vers l'état incolore du premier composé,In one embodiment, the first and second compounds are such that: the temperature of transition from the colorless state to the colored state of the second compound is greater than the transition temperature from the colored state to the colorless state of the first compound; compound,
- la température de passage de l'état coloré à l'état incolore du second composé est comprise entre les deux températures de changement d'état du premier composé.the temperature of transition from the colored state to the colorless state of the second compound is between the two change of state temperatures of the first compound.
Dans une réalisation, les températures de passage de l'état incolore à l'état coloré et passage de l'état coloré à l'état incolore du second composé coïncident respectivement avec les températures de passage de l'état coloré vers l'état incolore et de passage de l'état incolore vers l'état coloré du premier composé.In one embodiment, the transition temperatures from the colorless state to the colored state and from the colored state to the colorless state of the second compound respectively coincide with the transition temperatures from the colored state to the colorless state. and passing from the colorless state to the colored state of the first compound.
Dans une réalisation, le second composé comprend une encre thermochrome et/ou un composé à transition de spin.In one embodiment, the second compound comprises a thermochromic ink and / or a spin transition compound.
Dans une réalisation, le premier composé comprend une encre thermochrome et/ou un composé à transition de spin. Dans une réalisation, les premier et second composés, sont identiques et conditionnés lors de la fabrication du témoin chacun dans un état de coloration initial différent, l'un étant incolore tandis que l'autre est coloré.In one embodiment, the first compound comprises a thermochromic ink and / or a spin transition compound. In one embodiment, the first and second compounds are identical and packaged during manufacture of the control each in a different initial staining state, one being colorless while the other is stained.
Dans une réalisation, les premier et second composés sont disposés de manière à former un motif.In one embodiment, the first and second compounds are arranged to form a pattern.
Dans une réalisation, le premier composé passe de l'état incolore vers l'état coloré lorsque la température varie de manière croissante.In one embodiment, the first compound passes from the colorless state to the colored state as the temperature increases.
Dans une réalisation, le premier composé passe de l'état incolore vers l'état coloré lorsque la température varie de manière décroissante. Dans une réalisation le témoin comprend deux films dont au moins un est partiellement transparent, les deux films étant assemblé hermétiquement afin de contenir le premier et le second composés.In one embodiment, the first compound passes from the colorless state to the colored state as the temperature varies in a decreasing manner. In one embodiment the control comprises two films of which at least one is partially transparent, the two films being hermetically assembled to contain the first and the second compounds.
Dans une réalisation, le premier et le second composés, sont conditionnés dans deux compartiments séparés. D'autres caractéristiques et avantages de l'invention apparaîtront avec la description faite ci-dessous, cette dernière étant effectuée à titre descriptif et non limitatif en faisant référence aux figures ci-après sur lesquelles :In one embodiment, the first and second compounds are packaged in two separate compartments. Other features and advantages of the invention will appear with the description given below, the latter being carried out for descriptive and non-limiting purposes with reference to the following figures in which:
- les figures 1 et 2, déjà décrites, représentent le cycle de coloration en fonction de la température d'un composé thermochrome réversible ;FIGS. 1 and 2, already described, represent the coloring cycle as a function of the temperature of a reversible thermochromic compound;
- la figure 3 représente le cycle de changement d'état de spin en fonction de la température d'un composé à transition de spin ;FIG. 3 represents the spin state change cycle as a function of the temperature of a spin transition compound;
- la figure 4 représente un exemple d'utilisation de témoin selon l'invention ; - la figure 5 représente la variation de coloration d'un témoin selon l'invention lorsque le changement d'état du second composé thermochrome est irréversible ;FIG. 4 represents an example of use of a control according to the invention; FIG. 5 represents the color variation of a control according to the invention when the change of state of the second thermochromic compound is irreversible;
- les figures 6, 7 et 8 représentent différentes combinaisons des premier et second composés lorsque le changement d'état du second composé est réversible ;FIGS. 6, 7 and 8 represent different combinations of the first and second compounds when the change of state of the second compound is reversible;
- la figure 9 représente un mode de réalisation de l'invention dans lequel on utilise deux composés identiques dans des états de départ différents.FIG. 9 represents an embodiment of the invention in which two identical compounds are used in different starting states.
En référence aux figures 4 à 9, on décrit ci-dessous plusieurs modes de réalisation d'un témoin 10 de franchissement de seuil selon l'invention, apte à détecter un franchissement « à la baisse » et/ou à la « hausse », c'est-à-dire de détecter le franchissement d'une limite de température basse et/ou d'une limite haute. Ainsi, comme visible sur la figure 4, le témoin 10 se présente sous la forme d'une étiquette incolore, dans l'exemple autocollante, destinée à être apposée sur chaque produit devant être surveillé. Selon l'invention, le témoin 10 comprend un premier composé thermochrome réversible A et un second composé thermochrome B. Pour réaliser le composé A, on peut utiliser une encre thermochrome, par exemple comme celles décrites dans les documents EP1657073 et US5,558,699.With reference to FIGS. 4 to 9, several embodiments of a threshold crossing control device according to the invention, capable of detecting a "downward" crossing and / or "Rise", that is to say to detect the crossing of a low temperature limit and / or a high limit. Thus, as shown in FIG. 4, the control 10 is in the form of a colorless label, in the self-adhesive example, intended to be affixed to each product to be monitored. According to the invention, the control 10 comprises a first reversible thermochromic compound A and a second thermochromic compound B. To produce the compound A, a thermochromic ink can be used, for example as those described in the documents EP1657073 and US5,558,699.
Selon l'invention, la coloration du composé B doit intervenir à une température déterminée, de manière à pouvoir compenser un éventuel passage à l'état incolore du composé A si les variations de températures successives ont eu pour conséquence qu'après franchissement de la température seuil, le composé A a décrit un cycle complet de coloration/décoloration. Les exemples décrits ci-dessous montrent qu'en plus de procurer une sécurité absolue au témoin, la présence d'un second composé thermochrome B permet de réaliser un témoin assurant une surveillance à la fois à la baisse et à la hausse, permettant de s'assurer que la température est restée dans un intervalle donné ou une plage de surveillance.According to the invention, the coloring of compound B must take place at a predetermined temperature, so as to be able to compensate for a possible change to the colorless state of compound A if the successive temperature variations have had the consequence that after crossing the temperature threshold, compound A described a complete cycle of staining / discoloration. The examples described below show that in addition to providing absolute security to the control, the presence of a second thermochromic compound B makes it possible to produce a control which provides both downward and upward monitoring, allowing ensure that the temperature has remained within a given range or monitoring range.
Dans l'exemple de la figure 4, les composés A et B sont emprisonnés dans deux compartiments séparés du témoin 10, qui présente ainsi deux fenêtres de visualisation juxtaposées. Comme on peut le voir sur la figure 4, la lecture du témoin est très simple : comme l'état initial des deux composés A et B est l'état incolore, il y a eu défaut de conservation dès lors qu'au moins l'une des fenêtres affiche une coloration. En variante, les composés A et B peuvent être réunis dans un conditionnement unique, pour autant que leur mélange soit possible sans affecter le fonctionnement du témoin.In the example of Figure 4, the compounds A and B are trapped in two separate compartments of the control 10, which thus has two viewing windows juxtaposed. As can be seen in FIG. 4, the reading of the control is very simple: since the initial state of the two compounds A and B is the colorless state, there has been a lack of conservation since at least the one of the windows displays a color. Alternatively, the compounds A and B can be combined in a single package, as long as their mixing is possible without affecting the operation of the control.
Le témoin 10 décrit dans cet exemple est réalisé de manière à surveiller les vaccins décrits plus haut en référence à la figure 2. Ainsi, on voit sur les figures 5 et 6 que le composé A est identique au composé utilisé dans l'exemple de la figure 2 : il passe de l'état incolore ou peu coloré (état IA) vers l'état coloré (état IIA) à une température Tbasse-A proche de zéro degré Celsius, permettant ainsi de « marquer » le vaccin s'il a été conservé à une température inférieure à 00C, même temporairement. Selon l'invention, le témoin 10 comprend également un second composé thermochrome B, réversible ou non. La figure 5 décrit un mode de réalisation de l'invention ou le second composé thermochrome B présente un changement d'état irréversible. Le composé B est choisi de manière que sa température Thaute-B de passage de l'état incolore (état IB) à l'état coloré (état IIB) soit inférieure ou égale à la température de passage inverse Thaute-A du composé A. Ainsi, si les produits surveillés (état 1 ) ont franchi le seuil de O0C (état 2A, coloration de A), et que la température dépasse ensuite la trentaine de degrés, alors le composé A redeviendra incolore (état 4A), mais, peu avant ou bien au même moment, le composé B se colorera de manière irréversible (état 3A). Ainsi, la coloration de la fenêtre du témoin 10 correspondant au compartiment contenant le composé B sera définitive, quelles que soient les variations ultérieures de la température de conservation. Le témoin indiquera donc clairement et de manière sûre aux personnes concernées que le produit surveillé est endommagé et ne doit pas être utilisé. Dans l'exemple, la plage de surveillance du témoin 10 est définie par les températures Tbasse-A et Thaute-B-The control described in this example is carried out so as to monitor the vaccines described above with reference to FIG. 2. Thus, FIGS. 5 and 6 show that compound A is identical to the compound used in the example of FIG. FIG. 2: it moves from the colorless or slightly colored state (state I A ) to the colored state (state II A ) at a temperature T ba sse-A close to zero degrees Celsius, thus making it possible to "mark" the vaccine if it has been stored at a temperature below 0 ° C, even temporarily. According to the invention, the control 10 also comprises a second thermochromic compound B, reversible or not. FIG. 5 describes an embodiment of the invention where the second thermochromic compound B has an irreversible state change. Compound B is chosen so that its temperature T hau t e -B of transition from the colorless state (state I B ) to the colored state (state II B ) is less than or equal to the temperature of inverse passage T hau t e -A compound A. Thus, if the monitored product (state 1) crossed the threshold 0 O C (condition A 2, A staining), and the temperature then exceeds thirty degrees, then the compound A will again become colorless (state 4 A ), but, shortly before or at the same time, compound B will stain irreversibly (state 3 A ). Thus, the coloring of the control window 10 corresponding to the compartment containing the compound B will be final, regardless of the subsequent variations in the storage temperature. The witness will therefore clearly and clearly indicate to the persons concerned that the monitored product is damaged and should not be used. In the example, the monitoring range of the indicator 10 is defined by the temperatures T ba sse-A and T hau te-B-
Les figures 6, 7 et 8 représentent différentes variantes d'un mode de réalisation de l'invention dans lequel le composé B est un composé thermochrome réversible. Dans ce cas, il présente deux températures de changement TbasSe-B et Thaute-B, et les différentes variantes présentées ci- dessous dépendent des valeurs relatives de ces températures par rapport aux températures de changement d'état du premier composé A.Figures 6, 7 and 8 show different variants of an embodiment of the invention wherein compound B is a reversible thermochromic compound. In this case, it has two change temperatures T low eB and T high -B, and the different variants presented below depend on the relative values of these temperatures with respect to the change of state temperatures of the first compound A.
La figure 6 représente une variante dans laquelle les températures de changement d'état TbasSe-B et Thaute-B du second composé B sont telles que chaque changement d'état du composé B coïncide avec le changement d'état inverse du composé A. En d'autres termes, TbasSe-B est égale à Tbasse-A (ou très proche de Tbasse-A ) et Thaute-B est égale Thaute-A (ou très proche de Thaute-A)- Ainsi, le témoin 10 fonctionne de la même manière qu'à la figure 5, à la différence que, lorsque la température dépasse Thaute-B et que le composé B devient coloré (le composé A devenant alors incolore), la coloration du composé B n'est pas définitive. En effet, si la température est amenée à redescendre en dessous de TbasSe-B, alors le composé B redevient incolore. Cependant la sécurité procurée par le témoin selon l'invention est toujours totale car, au même moment, le composé A redevient coloré. Le témoin sera donc coloré si l'une des températures de changement d'état Tbasse-A ou Thaute-B, du composé A, a été franchie. Dans cet exemple, ce sont les deux températures de changement d'état du premier composé A qui définissent la plage de surveillance du témoin 10. Comme on va le voir dans les exemples suivants, il n'est pas nécessaire que les températures de changement d'état du composé B coïncident avec les températures de changement d'état inverse du composé A pour que le témoin fonctionne.FIG. 6 shows a variant in which the low TB and T high -B T-state change temperatures of the second B compound are such that each change of state of the compound B coincides with the inverse change of the compound A. In other words, T basS eB is equal to T low- A (or very close to T low- A) and T hau t e- B is equal to T hau t e- A (or very close to T hau t e - A) - Thus, the control 10 works in the same way as in Figure 5, except that when the temperature exceeds T high- B and compound B becomes colored (the compound A becoming colorless), the coloring of compound B is not definitive. Indeed, if the temperature is brought down below T low eB, then the compound B becomes colorless again. However, the security provided by the control according to the invention is always complete because, at the same time, compound A becomes colored again. The indicator will be colored if one of status change Lower temperatures T A or T B Upper, the compound A, has been crossed. In this example, these are the two change temperatures state of the first compound A which define the monitoring range of the control 10. As will be seen in the following examples, it is not necessary that the change of state temperature of the compound B coincide with the change temperatures. reverse state of compound A for the control to operate.
En effet, la figure 7 représente une variante dans laquelle le second composé B est tel que ses températures de changement d'état Tbasse-B et Thaute- B sont inférieures respectivement aux températures de changement d'état inverse du composé A. En d'autres termes, Tbasse-B est inférieure ou égale à Tbasse-A et Thaute-B est inférieure ou égale Thaute-A- L'intérêt de cette configuration est notamment d'obtenir, avec un même composé A, une plage de surveillance différente de celle de l'exemple de la figure 6. Dans le présent exemple, la plage de surveillance, plus resserrée, est définie par les températures TbasSe-A et Thaute-B- Le témoin fonctionne cependant de la même manière : l'état initial des deux composés A et B est l'état incolore (état 1 ). Si le témoin franchit la température Thaute-B, qui définit la limite haute de la plage de surveillance du témoin, alors le composé B passe à l'état coloré (état 2B). Si ce dépassement est important (état 3B), le composé B reste coloré tandis que le composé A ne change pas d'état et reste à l'état incolore. Si ensuite la température diminue et qu'elle franchit la limite basse de la plage de surveillance TbasSe-A, alors le composé A va passer à l'état coloré. Les deux composés A et B seront alors tous les deux à l'état coloré (état 4B). Si la température continue à descendre et devient inférieure à TbasSe-B, alors le composé B va repasser à l'état incolore, tandis que le composé A reste coloré (état 5B). Si, par la suite la température remonte et se stabilise à l'intérieur de la plage de surveillance, le composé A sera toujours coloré. La sécurité du témoin est donc absolue : dès lors qu'au moins une des températures limites de la plage de surveillance sera franchie, même temporairement et pour un court laps de temps, alors au moins un des composés A ou B sera coloré. La variante de la figure 7 montre de plus que l'on peut adapter le témoin de manière simple en combinant des composés thermochromes et leurs températures de changement d'état, pour définir avec précision la page de surveillance souhaitée.In fact, FIG. 7 represents a variant in which the second compound B is such that its change of state temperatures T ba sse-B and T high - B are respectively lower than the inverse change temperature of the compound A. In other words, T ba sse-B is less than or equal to Tbasse-A and T hau te-B is less than or equal T hau t e -A- The advantage of this configuration is in particular to obtain, with a even compound a, a different tracking range to that of the example of Figure 6. in the present example, the monitoring range, narrower, is defined by the Bass T eA and Th temperatures ute-B- witness however, works in the same way: the initial state of the two compounds A and B is the colorless state (state 1). If the control passes the temperature Th at te-B, which sets the high limit of the monitoring range of the control, then compound B changes to the colored state (state 2B ). If this overshoot is important (state 3 B ), compound B remains colored while compound A does not change state and remains in a colorless state. If then the temperature decreases and it crosses the lower limit of the monitoring range T basS eA, then the compound A will go to the colored state. Both compounds A and B will then both be in a colored state (state 4B ). If the temperature continues to fall and becomes lower than T low eB, then compound B will go back to a colorless state while compound A remains colored (state B ). If, subsequently, the temperature rises and stabilizes within the monitoring range, compound A will still be colored. The security of the witness is therefore absolute: as soon as at least one of the temperature limits of the monitoring range will be crossed, even temporarily and for a short period of time, then at least one of the compounds A or B will be colored. The variant of FIG. 7 further shows that the control can be adapted in a simple manner by combining thermochromic compounds and their change of state temperatures in order to precisely define the desired monitoring page.
Une troisième variante est représentée sur la figure 8. A la différence des variantes représentées aux figures 6 et 7, l'état initial des composés A et B est dans cet exemple l'état coloré. Dans cet exemple, les températures de changement d'état Tbasse-B et Thaute-B du second composé B sont supérieures respectivement à chaque température de changement d'état inverse du composé A. En d'autres termes, Tbasse-B est supérieure ou égale à Tbasse-A et Thaute-B est supérieure ou égale Thaute-A- Ce sont donc les températures TbasSe-B et Thaute-A qui définissent ici la plage de surveillance. Comme l'état initial des deux composés est l'état coloré, le témoin indiquera qu'il y a eu défaut de conservation si au moins l'un des deux composés est à l'état incolore, et non à l'état coloré comme pour les variantes des figures 6 et 7. Pour le reste, le fonctionnement est identique aux variantes des figures précitées.A third variant is shown in Figure 8. Unlike the variants shown in Figures 6 and 7, the initial state of the compounds A and B is in this example the colored state. In this example, the The temperature of the change of state T ba sse-B and T hau t e -B of the second compound B are respectively greater than each inverse change temperature of the compound A. In other words, T ba sse-B is greater than or equal to Tbasse-A and T hau te-B is greater than or equal to T ue t e -A- It is therefore the temperatures T low eB and T high -A which define here the monitoring range. Since the initial state of the two compounds is the colored state, the control will indicate that there has been a defect of conservation if at least one of the two compounds is in the colorless state, and not in the colored state as for the variants of Figures 6 and 7. For the rest, the operation is identical to the variants of the aforementioned figures.
Comme le montrent les exemples décrits ci-dessus, le témoin selon l'invention permet de surveiller le dépassement d'un seuil de température à la hausse ou à la baisse avec une sécurité totale quant à l'information fournie par le témoin : aucune falsification ou information accidentellement erronée n'est possible comme pour les indicateurs de l'art antérieur.As shown by the examples described above, the control according to the invention makes it possible to monitor the exceeding of a temperature threshold upwards or downwards with total security as to the information provided by the witness: no falsification or accidentally erroneous information is possible as for the indicators of the prior art.
En variante, au moins l'un des composés thermochromes utilisés comprend un composé à transition de spin, comme par exemple ceux décrits dans le document FR2755696. La figure 3 montre un exemple de cycle d'hystérésis de composés à transition de spin. En ordonnée il a été reporté une grandeur qui traduit l'état de spin et non l'état de coloration ; l'état de coloration présente un cycle d'hystérésis inversé comparable à celui représenté en figure 1. Ces composés présentent une transition d'états de spin, entre un état dit bas spin (LS) et un état dit haut spin (HS) qui est induite thermiquement, et qui est accompagnée de changement de configuration électronique et de modifications structurelles des molécules provoquant un changement abrupt du spectre d'absorption des molécules, et donc de la couleur des composés. Ainsi, dans l'exemple, les composés sont pourpres dans l'état bas spin (LS), alors que dans l'état haut spin (HS) ces composés sont blancs.Alternatively, at least one of the thermochromic compounds used comprises a spin-transition compound, for example those described in document FR2755696. Figure 3 shows an example of a hysteresis loop of spin transition compounds. On the ordinate, a magnitude has been reported which reflects the spin state and not the color state; the state of coloration exhibits an inverted hysteresis cycle comparable to that represented in FIG. 1. These compounds exhibit a transition of spin states, between a so-called low spin state (LS) and a so-called high spin state (HS) which is induced thermally, and that is accompanied by electronic configuration change and structural modifications of the molecules causing an abrupt change in the absorption spectrum of the molecules, and therefore the color of the compounds. Thus, in the example, the compounds are purple in the low spin state (LS), whereas in the high spin state (HS) these compounds are white.
Dans une autre variante, pour réaliser le témoin 10, on utilise deux composés thermochromes réversibles A et A' identiques, du type représenté à la figure 1 , mais amenés lors de la fabrication chacun dans un état initial différent l'un de l'autre. Ainsi, le composé A sera dans l'état initial I, tandis que le composé A' sera dans l'état initial II.In another variant, to produce the control 10, two identical reversible thermochromic compounds A and A ', of the type represented in FIG. 1, are used, but brought during the manufacturing each in a different initial state from each other. . Thus, the compound A will be in the initial state I, while the compound A 'will be in the initial state II.
Dans un premier exemple, les composés A et A' sont conditionnés dans deux compartiments séparés, de même que pour l'exemple de la figure 4. Ainsi, avant utilisation, la fenêtre du compartiment contenant A n'affiche pas de coloration, tandis que la deuxième fenêtre, celle du compartiment contenant A', affiche une coloration. Les deux fenêtres indiquent donc des états de colorations opposées. Le témoin 10 est ensuite apposé sur un produit à surveiller. Le fonctionnement du témoin 10 est alors le suivant : i) si la température de celui-ci dépasse Thaute-A, alors le composé A' va passer de l'état II à l'état I, tandis que le composé A ne modifie pas son état (état I). Les deux fenêtres indiqueront alors un même état de coloration, dans ce cas l'état incolore. ii) si, à l'opposé, la température du produit surveillé descend en dessous de Tbasse-A, alors le composé A passe de l'état I à l'étatIn a first example, the compounds A and A 'are packaged in two separate compartments, as for the example of FIG. Thus, before use, the window of the compartment containing A does not display coloring, while the second window, that of the compartment containing A ', displays a coloration. The two windows thus indicate states of opposite colorations. The control 10 is then affixed to a product to be monitored. The operation of the control 10 is then as follows: i) if the temperature thereof exceeds T hau t e -A, then the compound A 'will go from the state II to the I state, while the compound A does not change its state (state I). The two windows will then indicate the same coloring state, in this case the colorless state. ii) if, on the contrary, the temperature of the monitored product falls below T ba sse-A, then the compound A goes from state I to state
II tandis que le composé A' ne modifie pas son état (état II). Les deux fenêtres indiqueront alors un état identique : l'état coloré. iii) si le cas visé à l'alinéa ii) se produit après que la variation de température ait déjà abouti une première fois au cas visé à l'alinéa i), le résultat sera identique car alors les deux composés passent conjointement de l'état I vers l'état II lors du franchissement de TbasSe- iv) Idem, mutatis mutandis, si les cas ii) et i) se produisent successivement dans cet ordre.II while the compound A 'does not modify its state (state II). The two windows will then indicate an identical state: the colored state. (iii) if the case referred to in subparagraph (ii) occurs after the change in temperature has already occurred for the first time in the case referred to in subparagraph (i), the result will be identical because then the two compounds pass jointly from the state I to state II when crossing T basS e- iv) Idem, mutatis mutandis, if cases ii) and i) occur successively in this order.
On voit donc que, si elle est différente des autres exemples, la lecture du témoin reste toujours aussi simple : il y aura ici défaut de conservation dès lors que la coloration des deux fenêtre est identique, quel que soit l'état de coloration. La plage de surveillance est ici définie par l'intervalle entre Tbasse-A et Thaute-A-It is therefore seen that, if it is different from the other examples, the reading of the control remains always simple: there will be here lack of conservation since the coloration of the two windows is identical, whatever the state of coloration. The monitoring range is here defined by the interval between T ba sse-A and T high eA-
Dans un second exemple, représenté sur la figure 9, on emprisonne les composés A et A' dans un même conditionnement, et ceux-ci sont conditionnés lors de la fabrication de telle façon que leur différence de coloration dessine un motif, dans l'exemple en forme de croix. On peut par exemple obtenir le témoin de la figure 9 en utilisant le composé A, déposé dans son état II (coloré) à température ambiante, et en chauffant localement la partie destiné à former le motif, qui devient alors transparente. Dans l'exemple représenté à la figure 9, les températures de changement d'état du composé AIn a second example, represented in FIG. 9, the compounds A and A 'are trapped in the same package, and these are packaged during manufacture in such a way that their difference in color forms a pattern, in the example in the shape of a cross. For example, the control of FIG. 9 can be obtained by using compound A, deposited in its II state (colored) at ambient temperature, and by heating the part intended to form the pattern locally, which then becomes transparent. In the example shown in FIG. 9, the change of state temperatures of compound A
(ou A') sont de +1°C et +15°C. Avant utilisation, le témoin 10 présente donc une fenêtre de visualisation unique affichant un motif. On voit donc que si la température dépasse la température Thaute-A, la partie du témoin à l'état coloré va passer à l'état incolore, la surface du témoin 10 sera donc intégralement incolore. Inversement, si la température franchit la température Tbasse-A, alors la portion du témoin à l'état incolore passera à l'état coloré, le témoin étant alors entièrement coloré. Le témoin de la figure 9 indiquera donc un défaut de conservation dès lors qu'il ne permet plus de discerner aucun motif, que l'état indiqué soit incolore ou coloré. (or A ') are + 1 ° C and + 15 ° C. Before use, the indicator 10 therefore has a single viewing window displaying a pattern. So we see that if the temperature exceeds the temperature T hau t e -A, the portion of the control in the colored state will pass to the colorless state, the surface of the control 10 will be completely colorless. Conversely, if the temperature exceeds the temperature T ba sse-A, then the portion of the control in the colorless state will change to the colored state, the witness then being fully colored. The witness of FIG. 9 will therefore indicate a defect of conservation since it no longer makes it possible to discern any motive, whether the state indicated is colorless or colored.

Claims

REVENDICATIONS
1. Témoin (10) de franchissement de température, permettant d'établir si un produit, notamment un produit périssable, a franchi au moins l'une de deux valeurs de température seuil formant les extrémités inférieure et supérieure d'une plage de surveillance, le témoin (10) comprenant :1. Temperature crossing indicator (10), used to establish whether a product, particularly a perishable product, has passed at least one of two threshold temperature values forming the lower and upper ends of a monitoring range, the control (10) comprising:
- un premier composé (A) thermochrome réversible, présentant en fonction de la température et de son historique de variations soit un état coloré (IU) soit un état incolore (U) ou peu coloré, le passage d'un état à l'autre intervenant à deux températures distinctes selon que la température varie de manière croissante ou décroissante,a first reversible thermochromic compound (A) exhibiting, depending on the temperature and its history of variations, either a colored state (IU) or a colorless (U) state or little color, the transition from one state to another intervening at two different temperatures depending on whether the temperature is increasing or decreasing,
- un second composé (B) thermochrome, présentant en fonction de la température et de son historique de variations soit un état coloré (HB) soit un état incolore (IB) ou peu coloré,a second thermochromic compound (B) exhibiting, depending on the temperature and its history of variations, either a colored state (H B ) or a colorless (I B ) state or a colorless state,
- le premier composé (A) étant dans un état initial, à une température comprise ente les deux valeurs seuil, coloré (IU) ou incolore (U), un changement d'état intervenant lors du franchissement d'une des deux valeurs seuil,the first compound (A) being in an initial state, at a temperature lying between the two threshold values, colored (IU) or colorless (U), a change of state occurring when crossing one of the two threshold values,
- le second composé (B) étant dans un état initial, à une température comprise entre les deux valeurs seuil, coloré (HB) OU incolore (IB), un changement d'état intervenant lors du franchissement de la deuxième valeur seuil, dans le sens inverse du franchissement de la première valeur seuil, avant que le premier composé (A) ne revienne à son état initial, de sorte qu'au moins l'un des deux composés n'est plus dans son état initial dès lors qu'une des deux températures seuil a été franchie, temporairement ou non.- the second compound (B) being in an initial state, at a temperature between the two threshold values, colored (H B ) OR colorless (I B ), a change of state occurring when crossing the second threshold value, in the opposite direction of the crossing of the first threshold value, before the first compound (A) returns to its initial state, so that at least one of the two compounds is no longer in its initial state when one of the two threshold temperatures has been crossed, temporarily or not.
2. Témoin (10) selon la revendication 1 , dans lequel le changement de coloration du second composé (B) thermochrome est irréversible.The control (10) of claim 1, wherein the color change of the second thermochromic compound (B) is irreversible.
3. Témoin (10) selon la revendication 2, dans lequel la température de changement d'état du second composé (B) est :The control (10) of claim 2, wherein the change of state temperature of the second compound (B) is:
- inférieure ou égale à la température de passage de l'état coloré (IU) à l'état incolore (U) du premier composé (A) si ce passage s'effectue suivant une variation de température croissante ; - supérieure ou égale à la température de passage de l'état coloré (IU) à l'état incolore (U) du premier composé (A) si ce passage s'effectue suivant une variation de température décroissante- less than or equal to the temperature of transition from the colored state (IU) to the colorless state (U) of the first compound (A) if this passage takes place according to an increasing temperature variation; - greater than or equal to the temperature of transition from the colored state (IU) to the colorless state (U) of the first compound (A) if this transition takes place according to a decreasing temperature variation
4. Témoin selon la revendication 1 , dans lequel le second composé (B) est un composé thermochrome réversible.4. The control of claim 1, wherein the second compound (B) is a reversible thermochromic compound.
5. Témoin selon la revendication 4, dans lequel l'état initial des premier et second composés (A, B) est l'état incolore.5. The control of claim 4, wherein the initial state of the first and second compounds (A, B) is the colorless state.
6. Témoin (10) selon la revendication 5, dans lequel :The indicator (10) of claim 5, wherein:
- la température de passage de l'état coloré (HB) à l'état incolore (IB) du second composé (B) est inférieure ou égale à la température de passage de l'état incolore (U) vers l'état coloré (IU) du premier composé (A).the temperature of transition from the colored state (H B ) to the colorless state (I B ) of the second compound (B) is less than or equal to the transition temperature from the colorless state (U) to the state colored (IU) of the first compound (A).
- la température de passage de l'état incolore (IB) à l'état coloré (IIB) du second composé (B) est comprise entre les deux températures de changement d'état du premier composé (A).- The temperature of transition from the colorless state (I B ) to the colored state (II B ) of the second compound (B) is between the two change of state temperature of the first compound (A).
7. Témoin selon la revendication 1 , dans lequel l'état initial des premier et second composés (A, B) est l'état coloré.The indicator according to claim 1, wherein the initial state of the first and second compounds (A, B) is the colored state.
8. Témoin selon la revendication 7, dans lequel :8. The control of claim 7, wherein:
- la température de passage de l'état incolore (IB) à l'état coloré (IIB) du second composé (B) est supérieure à la température de passage de l'état coloré (IU) vers l'état incolore (U) du premier composé (A),the temperature of transition from the colorless state (I B ) to the colored state (II B ) of the second compound (B) is greater than the transition temperature from the colored state (IU) to the colorless state ( U) of the first compound (A),
- la température de passage de l'état coloré (IIB) à l'état incolore (IB) du second composé (B) est comprise entre les deux températures de changement d'état du premier composé (A).- The temperature of transition from the colored state (II B ) to the colorless state (I B ) of the second compound (B) is between the two change of state temperature of the first compound (A).
9. Témoin selon la revendication 5 ou 7, dans lequel les températures de passage de l'état incolore (IB) à l'état coloré (IIB) et passage de l'état coloré (HB) à l'état incolore (IB) du second composé (B) coïncident respectivement avec les températures de passage de l'état coloré (IU) vers l'état incolore (U) et de passage de l'état incolore (U) vers l'état coloré (IU) du premier composé (A).9. Control according to claim 5 or 7, wherein the transition temperatures from the colorless state (I B ) to the colored state (II B ) and transition from the colored state (H B ) to the colorless state. (I B ) of the second compound (B) coincide respectively with the transition temperatures from the colored state (IU) to the colorless state (U) and from the colorless state (U) to the colored state ( IU) of the first compound (A).
10. Témoin (10) selon l'une des revendications 4 à 9, dans lequel le second composé (B) comprend une encre thermochrome et/ou un composé à transition de spin.10. The indicator (10) according to one of claims 4 to 9, wherein the second compound (B) comprises a thermochromic ink and / or a spin transition compound.
11. Témoin (10) selon l'une des revendications 1 à 10, dans lequel le premier composé (A) comprend une encre thermochrome et/ou un composé à transition de spin. 11. The light (10) according to one of claims 1 to 10, wherein the first compound (A) comprises a thermochromic ink and / or a spin transition compound.
12. Témoin (10) selon la revendication 10 ou 11 , dans lequel les premier et second composés (A, B) sont identiques et conditionnés lors de la fabrication du témoin (10) chacun dans un état de coloration initial différent, l'un étant incolore tandis que l'autre est coloré.The control (10) according to claim 10 or 11, wherein the first and second compounds (A, B) are identical and packaged in the manufacture of the control (10) each in a different initial staining state, one being colorless while the other is colored.
13. Témoin selon la revendication 12, dans lequel les premier et second composé (A, B) sont disposés de manière à former un motif.13. A control according to claim 12, wherein the first and second compounds (A, B) are arranged to form a pattern.
14. Témoin (10) selon l'une des revendications précédentes, dans lequel le premier composé (A) passe de l'état incolore (U) vers l'état coloré (IU) lorsque la température varie de manière croissante.14. Indicator (10) according to one of the preceding claims, wherein the first compound (A) goes from the colorless state (U) to the colored state (IU) when the temperature varies increasingly.
15. Témoin (10) selon l'une des revendications 1 à 13, dans lequel le premier composé (A) passe de l'état incolore (U) vers l'état coloré (IU) lorsque la température varie de manière décroissante.15. Indicator (10) according to one of claims 1 to 13, wherein the first compound (A) goes from the colorless state (U) to the colored state (IU) when the temperature varies decreasingly.
16. Témoin (10) selon l'une des revendications précédentes, comprenant deux films dont au moins un est partiellement transparent, les deux films étant assemblé hermétiquement afin de contenir le premier et le second composés (A, B).16. Indicator (10) according to one of the preceding claims, comprising two films, at least one of which is partially transparent, the two films being assembled hermetically to contain the first and the second compounds (A, B).
17. Témoin (10) selon l'une des revendications précédentes, dans lequel le premier et le second composés (A, B) sont conditionnés dans deux compartiments séparés. 17. Control (10) according to one of the preceding claims, wherein the first and the second compounds (A, B) are packaged in two separate compartments.
PCT/FR2008/050716 2007-04-19 2008-04-21 Indicator indicating that a temperature threshold has been crossed WO2008148964A2 (en)

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