OA17962A - Detecting a marker in a liquid - Google Patents

Abstract

A detection device for detecting a marker in a liquid, comprising a reaction chamber, provided with a thermosensitive sensor, wherein said reaction chamber comprises an photopolymer capable of releasing or generating a chemical species that is capable of undergoing or initiating an exothermic or endothermic chemical reaction with a marker present in the liquid.

Description

The technical field of the présent invention is the thermal détection of reactive molécules in a liquid environment. Specifically, the présent invention relates to a détection device for detecting a marker in a liquid. The présent invention likewise relates to related Systems and methods.

Background of the invention

Currently, enthalpy changes due to chemically reactive species are detected using bench laboratory equipment, as DSC (Differential Scanning Calorimeter) or Photo-DSC analyzer. DSC equipment yield accurate information, but they can bebig and expensive.Moreover, theiroperation may require skilled people and the performed analysis can betimeconsuming.

The object of the invention is toprovidea cheap and portable solution for the détection of spécifie markers that can be detected when dissolved in a liquid at low concentration, in particular in fuel liquids, such as refined petroleum products including gasoline, diesel, kerosene, etc. The markerspreferablyhave a good solubility in the liquid, and arepreferably difficult to be identified, extracted and separated. The proposed solutions preferably provide a fast and reliable détection of the presence of amarker in a liquid, such as liquid fuel.

Summary of the invention

The mentioned problems and objects are solved by the subject-matter of the independent claims. Further preferred embodiments are defined in the dépendent claims and are also described in the following spécification.

According to an embodiment of the présent invention there is provided a détection device for detecting a marker in a liquid, comprising a reaction chamber, provided with a thermosensitive sensor, wherein said reaction chamber comprises an photopolymer capable of releasing or generating a chemical species that is capable of undergoing or initiating an exothermic or endothermie chemical reaction with a marker présent in the liquid.

According to another embodiment of the présent invention there is provided a System comprising a détection device according to a correspondingembodiment of the présent invention, a fuel as said liquid; and a marker dissolved in the fuel with a concentration < 150 ppm, which is preferably an epoxy compound.

According to another embodiment of the présent invention there is provided amethod for manufacturing a détection device according to any one of steps 1 to 10 comprising the steps of: depositing a photocurable epoxy composition layer exhibiting an excess of photoinitiator on the walls and/or on the floor of a reaction chamber and/or on a thermosensitive sensor placed in the reaction chamber;photocuring with UV radiation the photocurable epoxy composition layer exhibiting an excess of photoinitiator, so that unreacted acid molécules resulting from the décomposition of the photoinitiator maintain in the bulk and/or on the surface of the acidified photopolymer layer.

According to yet another embodiment of the présent invention there is provided a method for detecting a marker in a liquid, comprising the steps of introducing the marked liquid into the reaction chamber of a detecting device according to any one of a corresponding embodiment;letting the marker react in the reaction chamber with a chemical species released or generated from the photopolymer to cause a température increase or decrease at the position of the thermosensitive sensor by an exothermic or endothermie reaction of the marker and the chemical species released or generated from the photopolymer; andmeasuring the voltage or current output generated by the thermosensitive sensor placed in the reaction chamber.

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Brief description of the drawings

Embodiments of the présent invention, which are presented for better understanding the inventive concepts and which are not to be seen as limiting the invention, will now be described with reference to the figures in which:

Figure 1	shows a schematic view of a single sensor enthalpy detecting device according to an embodiment of the présent invention;
Figure 2	shows an exemplary characteristic curve of a cold unmarked fuel;
Figure 3	shows an exemplary characteristic curve of a cold marked fuel with approx.100 ppm concentration;
Figure 4	shows an example of a calculated différence between the curves in Fig. 2 and 3;
Figure 5	shows a schematic view of a dual sensor differential enthalpy detecting device according to an embodiment of the présent invention;
Figure 6	shows a schematic view of a dual sensor differential enthalpy mono-channel detecting device according to an embodiment of the présent invention;
Figures 7, 8, and 9	show schematic views of a dual sensor differential enthalpy vapor detecting device (bottom layer) according to an embodiment of the présent invention;

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Figure 10	shows a schematic view of l,2-epoxy-2-methylpropane;
Figure 11	shows a schematic view of 1,2,5,6-diepoxycyclooctane;
Figure 12	shows a schematic view of 1,2-epoxyhexane;
Figure 13	shows a schematic view of Diethylenetriamine;
Figure 14	shows a schematic view of Triethyl amine;
Figure 15	shows a schematic view of 3',-4'- (Epoxycyclohexane)methyl 3',-4'-Epoxycyclohexyl- carboxylate;
Figure 16	shows a schematic view of Tetrahydrofuran;
Figure 17	shows a schematic view of Benzylic Alcohol;
Figure 18	shows a schematic view of (3-Glycidoxypropyl) Trimethoxysilane (Silquest A187);
Figure 19	shows a schematic view of 9,10-Dibutoxyanthracene (Anthracure UVS1331);
Figure 20	shows a schematic view of Triarylsulfonium hexalfuoroantimonate sait (1:1 in propylene carbonate);
Figure 21	shows a schematic view of Araldite ECN9699; and

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Figure 22 shows a schematic view ofl, 4-Bis(hexafluoro-2-hydroxy-

2-propyl)benzene [1, 4-HFAB].

Detailed description

According to an embodiment of the présent invention, a détection device is provided that is able to identify a highly diluted marker in a liquid by measuring the reaction enthalpy of the reaction between said marker and a component inside the device. According to a further embodiment of the présent invention, a device can be achieved that detects low concentrations of different types of markers diluted in a fuel (at total concentration of preferably < lOOppm for ail markers). Such devices can contain a polymer able to release a chemical species (preferably an acid) that reacts with the marker dissolved in the liquid, developing a reaction heat that can be in turn detected by a pyroelectric thermal sensor provided in the device, preferably close to the polymeric active surface. The sensor signal can be preferablya function of the kinetic reaction mechanism.

In order to hâve a lab-on-chip of small size able to detect one or more markers solubilized in the liquid fuel at a total concentration equal to or lower than 100 ppm, a device according to an embodiment of the invention can contain a photopolymeric material able to generate or release acidic species and a pyroelectric sensor able to detect température variations of a liquid close to the photopolymeric material. The device of a corresponding embodiment comprises three communicating areas: an injection chamber where the marked fuel is introduced; a reaction chamber, where the thermosensitive sensor is placed, that is connected to the injection chamber and thatcontains the photopolymeric layer capable of releasing the chemical species that reacts with the marker; and a third chamber, connected to the reaction chamber, used for venting the device.

The marker dissolved in the fuel reacts with a chemical species, preferably an acid, released or generated by the photopolymer; and the reaction generates or absorbs heat (exothermic

-517962 or endothermie reaction) with a distinctive kinetic profile. The reaction heat produces a température variation (i.e. a température increase or decrease, depending on the reaction being exothermic or endothermie) on the sensor located in the device; and the sensor, as a conséquence of the température variation, generates a voltage or current signal. The shape of the curve resulting from the voltage/current signal vs. time highly dépends on the type of the one or more markers and their respective concentration, as well as on the chemical characteristics of the photopolymeric layer contained in the reaction chamber, in particular the kind and amount of the chemical species that is released or generated and its reaction kinetics with the one or more marker.

According to a further embodiment, the device is configured to detect or react to the presence of one or more reactive markers dissolved in a liquid. In principle, any compound that is capable of reacting with thechemical species (preferably an acid) that is released by the photopolymer can be used as a marker, as any such reaction will either be endothermie or exothermicand will give rise to a certain shape of the curve measured as signal by the sensor.

The marker of the présent invention is preferably one or more compounds selected from the following:

- inorganic and organic bases, of which organic bases are préférable, with aliphatic or aromatic amines being more préférable,and which further preferably hâve one or more basic nitrogen atoms;

- compounds capable of undergoing an addition reaction upon contact with the chemical species released by the photopolymer, preferably ethylenically unsaturated compounds, more preferably those having a terminal ethylenically unsaturated group, including compounds having avinyl,allylic, or vinylether group.

- esters, preferably carboxylic acid esters, which are preferably able to undergo saponification upon reaction with the chemical species released by the photopolymer;

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- silanes of formula SiR^RbR^ wherein at least one of Ri, R₂, R3, and Rrepresents a hydrogen atom and the remaining represent an organic group, preferably an alkoxy group having 1 to 6 carbon atoms,

- compounds having an epoxy group which are preferably able of performing a ring-opening reaction upon contact with the chemical species released by the photopolymer, preferably compounds having more than one epoxy group,

- méthacrylates and acrylates (in the following commonly referred to as (meth) acrylates), which are preferably Ci_₆alkyl esters of acrylic acid and methacrylic acid; and

- alcohols having one or more hydroxyl groups, preferably aliphatic alcohols or aromatic alcohols, such as éthanol, propanol, butanol, hexanol or phénol.

In this group, amines and epoxy compounds are preferred.

Each molécule belonging to these chemical classes will exhibit a distinctive kinetic reaction curve. This will allow the device to identify its presence and concentration in a liquid, e.g. by comparingthe obtained signal with a predetermined expected (stored) signal or curve.

In the method for detecting a marker, the marker may serve as authenticating means for authenticating the quality and/or origin of the liquid. For this purpose, the marker is typically présent in a concentration of 1,000 ppm or less, preferably 500 ppm or less, and more preferably 100 ppm or less, in the liquid to be tested. Herein and throughout the description, values referred to in ppm or % are by weight.

The liquid contains one or more markers. Herein and throughout the description, the phrase one or more is used to dénoté that one or more of the respective element is présent, such as one, two, three, four, five, six, or seven. Preferably, one or more means one, two or three.

In a preferred embodiment the device is especially adapted to work with epoxies, vinylethers and amines. For these three classes, there are different types of reactions, -717962 including a ring opening cationic addition mechanism (which may be a polyaddition); a cationic addition mechanism (which may be a polyaddition); andan acid-base reaction.

Generally, adevice according to embodiments of the invention can be made in a two-part configuration, including a top part and a bottom part that are assembled together within a précisé alignment using different techniques like heat bonding, adhesive bonding, solvent bonding, laser welding etc.

Figure 1 shows a schematic view of a single sensor enthalpy detecting device according to an embodiment of the présent invention.

The shown device comprises a substrate 1 made of organic or inorganic material that is preferably résistant to the target liquid, such as fuel. Thematerial is preferably suitable for mechanic machining, so that it can be well machined by mechanical manufacturing techniques (drilling, milling, etc...) or photolithographic patterning, in order to obtain the hydraulic circuit and the i n let/outlet holes.

The device is provided with an injection chamber 2 having an inlet 3 for introducing the liquid or fuel. The injection chamber is in communication with the reaction chamber 5 where the pyroelectric sensor 6 is arranged.

A suitable pyroelectric sensor of small size can be, for example, provided as a pyroelectric device that comprises a plurality of layers of a polar dielectric material exhibitingpyroelectric properties. The device may further comprise a plurality of conductive électrodes, wherein each conductive electrode is substantially in contact with at least a portion of one surface of a respective at least one of said plurality of layers of polar dielectric material. Said électrodes are then electrically connected in a parallel configuration as to form a sériés of capacitors comprised of said plurality of layers of polar dielectric material and plurality of conductive électrodes. By means of such a configuration, a pyroelectric sensor can be obtained that provides a sufficiently small form factor as well a sufficient sensitivity in terms of output signal resolution vs. heat exchange in the active région and time.

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Next, the photopolymer capable of releasing the chemical species that reacts with the marker is described.

In the présent invention, the term photopolymer is used to dénoté a polymer that is produced by reaction of a polymerizable composition including monomers by initiation of the polymerization reaction by means of a photopolymerization initiator. That is, the polymerizable composition is irradiated with electromagnetic radiation (typically UV light with a wavelength in the range from 200 to 380 nm, or with light of a wavelength of e.g. up to 450 nm) to décomposé a photopolymerization initiator. Thereby, the photopolymerization initiator is decomposed, causing the formation of radicals or other species (such as cations) capable of initiating the polymerization reaction ofthe polymerizable components in the polymerizable composition.

Using a suitable process, the photopolymeric material is deposited on the walls and the floor ofthe reaction chamber and/or on the sensor 6 itself. The réticulation is carried out by means of UV radiation using a traditional UV mercury lamp or a LED irradiation system.The polymerization reactionis initiated by means of UV radiation using a conventionalUV mercury lamp or a LED irradiation system.

The photopolymer is typically an epoxy based material that can provide high chemical résistance to the liquid (e.g. the fuel) after the photocuring. It is crucial that the formed photopolymeris able to generate or release a chemical species that is capable of reacting with the marker présent in the liquid fuel.

This species may be included in the photopolymer at the time of contact with the liquid, and is then released into the liquid to react therewith, such as in the case of an acid resulting from an excess of (cationic) photoinitiator used and decomposed at the time of forming the photopolymer. Yet, the chemical species may also be generated by the photopolymer as reaction to an external stimulus. For instance, it is envisaged to use a photopolymer that is able to generate acids under irradiation in the UV (200 - 380 nm) or visible spectrum. Also, it is envisages that a part of the photoinitiator contained in the formulation remains unreacted until contact with the liquid in the device.

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During the contact, an external stimulus may be used to generate the chemical species (e.g. the acid), for instance by UV exposure.

One way how this can be achieved is e.g. by employing an excess of photoinitiator, which is able to generate the chemical species that reacts with the marker molécule. This chemical species may for instance be acid molécules that are reactive with the marker, leading to e.g. polymerization or ring-opening reaction of epoxy functionalities.

The exceeding unreacted chemical species, e.g. the acid, remains absorbed inside the bulk of the photopolymer and adsorbed on the surface of the photopolymer. A suitable outlet 4 allows the correct liquid flow, venting the hydraulic circuit.

In the présent invention, the photopolymer is capable of generating or releasing a chemical species that reacts with the marker in the liquid in an exothermic or endothermie reaction. The chemical species released or generated by the photopolymer can be any compound capable of reacting with the marker in an endothermie or exothermic reaction, but is preferably an acid. Herein, the term acid is not limited to Bronsted-acids, but also includes Lewis-acids. Preferably, the acid is a Bronsted acid, and further preferably is a Bronsted having a pKa of 5 or less, more preferably 1 or less, and even further preferably 0 or less. It above ail préférable that the acid is a superacid, i.e. is an acid with an acidity greater than that of 100% pure sulfuric acid, which has a Hammett acidity function (H0) of -12. Examples of such acids include hexafluoroantimonic acid or hexafluorophosphoric acid

The top device part comprises a printed circuit board (PCB) to which the pyroelectric sensor 6 is bonded and two conductive tracks 7 ledout the signal from the sensor to an external circuit, such as an instrument 8 (data acquisition hardware or an oscilloscope, for example) in order to collect the data.When the liquid or fuel, containing a reactive marker, is injected into the device, it contacts the photopolymer close to the pyroelectric sensor. The photopolymer released the chemical species, e.g. an acid, and the reaction takes place on the photopolymer surface. The sensor measures the reaction heat and the

-1017962 signal is readout by the electrical tracks of the PCB.The recording instrument 8generates a plot of voltage (or current) as a function of time. The plot shape will be dépendent on the kinetic of the reaction and so it will dépend on the molécule type and its concentration inside the fuel. In general, the signal indicates the température change over time.

A prototypal device implementing an embodiment of the présent invention has been prepared to comprise a reaction chamber coated with a photopolymer capable of releasing an acid and a pyroelectric sensor nearby. An oscilloscope has been interfaced to the sensor which detects the température variations inside the reaction chamber, in order to collect a plot with the voltage vs. time.In this prototypal device two different liquids hâve been injected in sequence: (1) fuel (diesel) without additive (cf. Figure 2); and (2) fuel (diesel) containing areactive marker (approx. lOOppm of l,2-epoxy-2methylpropane) (cf Figure 3).

In each experiment the injected liquid and the sensor initially were not at the same température. According to a further embodiment, a configuration can be provided for bringing the liquid and the sensor into thermal equilibrium, by means of, for example, a suitable thermostatic ancillary equipment, in order to hâve no cooling effect during the first contact of the liquid to the sensor. This may be particularly advantageous for a more secure identification of the marker, as the measured signal reflects the reaction kinetics of the reaction. The shape of the obtained signal curve may then be different for different températures, as the reaction kinetics can differ at different températures.

Figure 2 shows an exemplary characteristic curve of a cold (near to 20°C.) unmarked fuel. Specifically, the results are shown of the first test performed with simple fuel, without any marker: the liquid was at a lower température with respect to the sensor, so the oscilloscope recorded a négative voltage variation, due to the cooling down of the pyroelectric device. There wasalso noreactive additive other than a marker in the fuel, therefore there appeared no evidence of a heating effect due to exothermic

-1117962 reactions within the device chamber. As a conséquence, the température différence between the liquid and sensor plays the major rôle in the output voltage signal.

Figure 3 shows an exemplary characteristic curve of a cold marked fuel. In this second test, the fuel containedapprox.. 100 ppm of a reactive marker (l,2-epoxy-2methylpropanejwas injected into the reaction chamber. The output signal is shown in Figure 3, where, during the first few seconds, one observes an opposing effect that contrasts the sensor cooling observed and described in conjunction with figure 2: after the first descending part of the curve, due to the sudden contact between liquid and sensor, there is a nearly fiat portion, indicating that an exothermic effect was contrasting the cooling. This exothermic effect is a heating effect caused by the expected exothermic reaction of the reactive marker with the acid species released by the photopolymer, close to the sensor.

As expected, the reaction can bequite fast and as a conséquence of the low concentration it can be advisable to zoom-inon the thermogram, focusing onto the first seconds in order to hâve a more précisé analysis. As previously mentioned, a possible further improvement could include a température matching of the fuel and the sensor before letting the reaction take place. This would avoid the physical cooling effect and the pure reaction signal would be obtained.

Figure 4 shows an example of a calculated différence between the curves in Fig. 2 and 3. In preliminary tests, the signal has been cleaned from the unwanted cooling effect subtracting numerically the first experimental curve (cf. Figure 2) from the second one (cf. Figure 3). The resuit of this différence operation is depicted in Figure 4 that demonstratesthe net signal depending on the chemical reaction, in this graphie the subtraction of the two plots is highlighted: the shape of this function and in particular its intégral and the peak voltage value reached is dépendent on the enthalpy and on the reaction kinetic of the additive with the acid species generated from the photopolymer formulation. It can be of advantage to get a high reproducibility of both reaction chambers and sensors with respect to the processes and materials adopted

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Figure 5 shows a schematic view of a dual sensor differential enthalpy detecting device according to an embodiment of the présent invention. According to this embodiment, adifferential approach isadopted to simplify the détection equipment. In this case, after the injection chamber 2 the fuel splits up in two flowpaths, reaching at the same time, but independently, two pyroelectric sensors 61 and 62 arrangedin two separated/different chambers. The outlets 4 allow the venting of the hydraulic circuit. Only one of these two chambers will contain the photopolymer 51 so that only in this chamber the reaction will take place. Both the sensors will record the effect due to the different température of the liquid with respect to the sensor, but only one will detect also the reaction heating, because of the presence of the chemical species released or generated by the photopolymer inside its own chamber. Choosing the suitable poling direction for each sensor and connecting them opportunely through the wires 71 and 72, a differential signal can be directly obtained and recorded or displayed in the measuring equipment 8, without the need of numerical operations. This embodiment could avoid the need of the preliminary température matching of fuel and sensor.

in the fuel marker detecting devices according to embodiments of the présent invention, the photopolymer5 canbe arranged as close as possible to the pyroelectric sensor 6, so that the heat generated through the reaction at the polymer surface can cause an appréciable and well-pronounced effect in the sensor, before spreading throughout the whole liquid. Therefore, the reaction chamber size can be designed to house the sensor, allowing the liquid to flow without leaving too much room between the chamber walls and the sensor surface.

A possible alternative solution is to coat the surface of the sensor itself with the photopolymer, instead of or in addition to coating the reaction chamber walls: the close proximity between the sensor and the reactive surface can allow for a very effective

-1317962 response of the sensor to the heat generated by the reaction. Such a situation is also depicted in Figure 5, where the sensor 61 is uncoated, whilst the sensor 62 has on its own surface the photopolymer coating 51, able to react with the fuel marker. Of course, the previous solution, where the coating is on the internai chamber walls, could be conveniently pursued also in a differential embodiment.

Figure 6 shows a schematic view of a dual sensor differential enthalpy mono-channel detecting device according to an embodiment of the présent invention. There, the differential approach is accomplished in a device with a single reaction chamber; this solution can provide the advantage to hâve a simplified hydraulic circuit. In this embodiment the uncoated sensor 61 and the coated one 62 are connected at one end with the contact lead 74, whilst the other ends, through the wires 73, provide the differential electrical signal for the measuring equipment 8.

Figures 7, 8, and 9 show schematic views of a dual sensor differential enthalpy vapor detecting device (bottom layer) according to an embodiment of the présent invention. Specifically, in conjunction with these figures it is described an alternative device configuration with a higher sensitivity able to generate and detect vapors and more in general volatile fractions from the marked fuel or liquid. This configuration and the related methodology concentrate the marker contained into the fuel increasing the final output signal. This device comprises a heater element 76 (e.g. an electrical resistor) on the bottom layer (cf. figure 7); this bottom layer 77 could be a simple PCB which contains an inlet hole 3. On the top layer (cf. figure 8) there is arranged a microhydraulic circuit 75 which is preferablybonded to the bottom of the device; this channel can thus convey the liquid on the heater element 76 where it is heated to a spécifie température next to the boiling point of the marker, with preferably a controlled rate. The vapor having a concentrated fraction of marker can thus contact the two sensors 62 and 61,and the reactive polymer 51 nearby sensor 62canreact with the concentrated marker giving a characteristic signal function of the reaction enthalpy between vaporized marker and reactive polymer. The fuel or liquid could contain more than one marker with different boiling points. In general, different markers can be

-1417962 detected separately as the température increases. Preferably, the device is adapted to work at atmospheric pressures thanks to the outlet hole 4.

The configuration described in figure 9 provides a signal having less background noise (due to contact between polymer and not-reactive fuel fraction) and which is, in an advantageous manner, in principle able to detect very low concentrations of the one or more markers. Finally, this method may also increase the selectivity by introducing a crossing évaluation of physical properties of each molécule marker (the boiling point) in parallel to the enthalpy reaction with a reactive polymer.

Different chemical species diluted into the diesel fuel (provided by ENI) at a concentrations of 100 ppm hâve been tested as markers: l,2-epoxy-2-methylpropane; 1,2,5,6diepoxycyclooctane; 1,2-epoxyhexane; and diethylenetriamine. These markers are listed below in Table 1, and their molecular structures are reported in Figures 10 to 15. The output voltage levels detected with the pyroelectric device were in the range 1 to 5mV, depending on the additive type.

The epoxy compounds are able to react withthe chemical species released by the photopolymer, e.g. on the surface of the photopolymer bywell-known cationic polyaddition ring opening reaction initiated by an acid released from the photopolymer. The amine tested is able to react with the released chemical species, i.e. an acid in this case, on or close to the surface of the photopolymer bya common acid-base reaction.

The different reaction mechanisms are well noticeable by evaluating the kinetics of the reaction: the epoxy ring opening réactions are faster than the amine reaction. This demonstrates that even within the the same molecular class itis possible to distinguish between the presence of a certain compound employed as a markerand another by monitoring the intensity of the signal with respect to the reaction time. For example, two solutions containing different epoxy molécules in the same concentration in weight, but having different epoxy équivalent values or different degrees of molécule mobility, will typicallygive a different voltage signal.

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Other possible reactive compounds commercially available from supplies such as Sigma Aldrich and which areconsidered suitable for the use as marker in the présent inventionare listed in Table 3.

The photopolymer forms a reactive coating in the device. The components used in the formulation are summarized in Table 4. Their molecular structures are reported in Figures 16 to 22.

Three formulations, used for the application, are listed in Table 5 for comparison. Ail of them were adopted, but the preferred one is F241W.

The reactivity toward markers in table 2 hâve been tested by means of DSC instrument by introducing each pure marker in contact to the photopolymer. The instrument records the heating or cooling signal characteristic of the reaction.

Each molécule tested in table 1 provides an appréciable heating or cooling signal détectable by DSC instrument. The pyroelectric sensor is able to detect exothermic and endothermie reactions between marker and photopolymer. In table 2 some reactive markers toward polymeric formulation F241W hâve been tested by means of DSC equipment. Pure diesel has been tested as well showing no appréciable DSC signal.

DSC évaluations hâve been executed with the following procedure:

• Déposition of a known quantity of photopolymerizable composition into an aluminum pot;

• UV exposure of the photopolymerizable composition by means of UV Fusion equipment with exposure energies equals or higher than 2000 mJ/cm2 in UVA, UVB, UVC région;

• Déposition of the UV exposed sample into DSC instrument;

• Déposition of a small amount of one marker listed in table 2 in contact with the UV exposed photopolymer;

• Detecting of the characteristic heat of reaction.

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In table 2 are also listed solubility data of tested markers in diesel fuel.

Ail the formulations are in form of liquid and could be dispensed on the desired surface by spray or spin or dip coating techniques or also using a microsyringe. Once dispensed, the polymeric compositioncould be photocured using a UV radiation source with an émission wavelength in the range of 250 to 450 nm. In this spécifie case, the irradiation causes the décomposition of the photoinitiator and further leads to the génération of super acid species that are stabilized in the photopolymermatrix. After the réticulation, the photopolymer is ready to use, without any additional process.

As previously mentioned, the photopolymeriazble composition can be dispensed either on the internai walls of the reaction chamber or onto the surface of the pyroelectric sensor; the latter solution could provide a better heat transfer to the sensor, if the polymer coating layer is very thin.

Three photocurable epoxy compositions exhibiting an excess of photoinitiators hâve been used to préparé the photopolymer in the reaction chamber of the détection device. These photopolymers are able to release acidic species upon contact with a liquid, such as fuel. Their compositions before UV irradiation are listed in table 5.The components are listed in table 4.

Table 1: Additives tested in the fuel

Additive name By

1.2- epoxy-2-methylpropane

1,2,5,6-diepoxycyclooctane Sigma- Aldrich

3',4'-(Epoxvcvclohexane)methyl3',4'Epoxycyclohexyl-carboxylate

1.2- epoxyhexane

Diethylenetriamine

Triethylamine

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Table 2:List of markertested on F241W polymer formulation

Maximum evaluated

Ingrédients concentration of markersoluble

Heat Variation into diesel fuel l,2-epoxy-2- methylpropane (Sigma-Aldrich) < 10000 ppm

Exothermic

1,2,5,6diepoxycyclooctane (Sigma-Aldrich) < 100 ppm

Exothermic

3',4'-(Epoxycyclohexane) methyl 3',4’

Epoxycyclohexyl< 10000 ppm

Exothermic carboxylate (Sigma-Aldrich)

1,2-epoxyhexane
(Sigma-Aldrich)	< 1000 ppm	Exothermic
Diethylenetriamine (Sigma-Aldrich)	< 100 ppm	Exothermic
Triethylamine (Sigma-Aldrich)	< 1000 ppm	Endothermie
Diesel fuel (EN 1)	/	No signal

Table 3: List of possible epoxy additives

Name

Molecular Formula

Allyl glycidyl ether	C6H10O2
Bis[4-(glycidyloxy)phenyl]methane	C19H20O4
1,3-butadiene diepoxide	C4H6O2

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1,4-butanediol diglycidyl ether	C10H18O4
Butyl glycidyl ether	C7H14O2
tert-butyl glycidyl ether	C7H14O2
1,4-cyclohexanedimethanol diglycidyl ether	C14H24O4
Cyclohexene oxide	C6HioO
Cyclopentene oxide	C5H8O
Dicyclopentadiene dioxide	C10H12O2
Dieldrin	C^HsCUO
1,2,7,8-diepoxyoctane	C8H14O2
Diglycidyl 1,2-cyclohexanedicarboxylate	C14H20O6
N,N-diglycidyl-4-glycidyloxyaniline	C15H19NO4
1,2-epoxybutane	c4h8o
2,3-epoxybutane	c4h8o
3,4-epoxy-l-butene	c4h6o
3.4- epoxycyclohexylmethyl- 3.4- epoxycyclohexanecarboxylate	Ci4H2o04
1,2-epoxydodecane	C12H24O

Table 4: list ofthe polymer components

Araldite ECN9699

Huntsmann's aromatic epoxy oligomer derived from

Novolac resin

1,4-HFAB

Fluorinated aromatic diol by Central Glass, used in a cationic System as a chain transfer promoter 1331-UVS Anthracure

Photosensitizer for cationic Systems produced by

Kawasaki Kasei Chemicals LTD.

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Triarylsulfonium hexalfuoroantimonate sait (1:1 in propylene carbonate)

Cationic photoinitiator useful to generate the superacid by means of UV irradiation, from SigmaAldrich.

(3-Glycidoxypropyl) Trimethoxysilane (Silquest A187)

Adhesion promoter by Momentive.

Byk 310

Non ionic silicone-containing surface additive for solvent-free and solvent-borne coating Systems, by Byk

Chemie

Tetrahydrofuran and Benzylic alcohol

Common organic solvents by Sigma-Aldrich

Araldite ECN9699 is an aromatic epoxy oligomer used into the formulation; it defines, after the polymerization step, the chemical, physical and mechanical properties of the polymer. This oligomer is able to reticulate by cationic polyaddition mechanism.

1,4-HFABis a diol used into the formulation as a chain transfer agent for the cationic polyaddition of the epoxy monomer/oligomer (Araldite ECN9699). This component contributes to an increase of epoxy conversion into the final polymer. It also reduces the réticulation density of the polymer, increasing its flexibility.

1331-UVS Anthracureis an anthracene compound used in order to absorbe UV-Vis radiation at wavelengths where the photoinitiator is not photosensible. The 1331-UVS Anthracure excited state induces décomposition of the photoinitiator and conséquent génération of superacid polymerization initiator.

Triarylsulfonium hexalfuoroantimonate saltis a photoinitiator that initiâtes, under UV radiation exposure, the epoxy ring opening. UV irradiation at certain wavelengths produces photoinitiator décomposition and conséquent superacid initiator génération

-2017962 (hexafluoroantimonic acid). Once the epoxy réticulation is concluded ail the superacid excess remain absorbed into the polymeric structure.

(3-Glycidoxypropyl) Trimethoxysilane (Silquest A187) is an adhesion promoter able to react contemporary with polar groups présent on a surface (typically hydroxides, amines and thiols) and the epoxy based formulation, developing high adhesion between the polymer and the surface.

Byk 310 is a surfactant useful for solvent based Systems to reduce their surface tension. It increases the wettability of liquid formulation, before its réticulation, toward surfaces like plastic, metals, etc...

Tetrahydrofuran and Benzylic alcohol (phenol)are two common organic solvents useful to solubilize ail the ingrédients inside an homogeneus low viscous formulation. Organic solvents contribute to reduce surface tension ofthe liquid formulation.

Table 5: Further Embodiments

F239W F240W F241W

Name % Wt

Araldite ECN9699	44,24	44,24	22,12
Benzylic alcohol	28	0	0
Tetrahydrofuran		28	14
1, 4-bis(hexafluoro-2-hydroxy-2propyl)benzene [1, 4-HFAB]	10	10	5
(3-glycidoxypropyl)trimethoxy- silane[Silquest A187]	5,14	5,14	2,57
9,10-dibuthoxyanthracene [1331-UVS Anthracure]	0,47	0,47	0,23

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Triarylsulfonium hexalfuoroantimonate sait (1:1 in propylenecarbonate)

12 56

Byk310 0,15 0,15 0,075

The ingrédients listed in table 4 and 5 are Araldite ECN9699, Triarylsulfonium hexafluoroantimonate sait and one organic solvent in order to solubilize these two components.

In principle any photopolymerizable composition having epoxy based oligomers/monomers can be used in the présent invention. The photoinitiator contained therein should be able to produce a suitable amount of acid (preferably superacid) after UV exposure. In many instances it is observed that the higherthe pKa value ofthe acid, the higher is the heating or cooling signal is detected by the pyroelectric sensor.

So it is préférable to hâve photoinitiators having anionsof superacids, like hexafluoroantimonate, hexafluorophosphate, Tris(4-(4- acetylphenyl)thiophenyl)sulfonium tetrakis(penta-fluorophenyl)borate, ortris(trisfluoromethanesulfonyl)methide.

If an epoxy-based photopolymer capable of releasing an acid is used, and the acid released therefrom is derived from a decomposed photoinitiator, a correct value ofthe starting ratio epoxy/photoinitiator is important. A photoinitiator weight ratioequal to higher than 10%, preferably equal to or higher than 50%, and in some cases equal to or higher than 100% with respect to the epoxy starting material prior to the formation of the photopolymer (i.e. before irradiation)is préférable.

After UV irradiation, some of the initiator will be consumed, and possibly there is also a certain loss of more volatile fractions. The formed photopolymer after UV irradiation preferably contains acids and/or unreacted photoinitiator in an amount of 0.1-5% by weight, or 1 - 8% by weight, or 2 -10% by weight, in order to hâve a good reactivity with the marker.

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It is self-evident to the skilled person that the organic solvents used in the formulation should not inhibit the photogeneration of e.g. acid species or the stabilization of carbocationic species in the epoxy fraction. It is therefore préférable to exclude the presence of any basic compound in the formulation, such as amines, amides, azotate cycles, thiols, sulfides.

Suitable solvents like alcohols, ethers, esters, aromatic hydrocarbons, glycoethers could be useful to dilute the formulation.

It is préférable to hâve a polymer like F241W having an ïntrinsic ability to be swelled by the marker contained into the fuel; the higher the marker perméation is, the higher is the reaction volume and consequently the higher is the signal detected by the pyroelectric sensor.

It is préférable to use a polymer which is soft, i.e. exhibits a low glass transition température (Tg) of 150 °C or less, preferably 130°C or less. . In such a way, the release of acid from the polymer is facilitated.

At a température change rate of 10°C/min between 25 and 200°C we hâve measured the following values of Tg for the polymers obtained by the photocurable compositions in Table 5:

F239W and F240W: Tg = 124 °C

F241W : Tg = 54 °C

The used photopolymer exhibits therefore preferably a Tg between 25° and 150°C, more preferably between 45° and 130 °C.

The markers proposed in this invention are difficult to be found out once dissolved into the fuel, and their détection is performed using a spécifie (and typically unknown) polymer. Therefore, the présent invention provides a method for authenticating a material marked

-2317962 with a marker, as a person wishing to forge the liquid would not only hâve to find out about the presence and concentration of the marker, but would also need to know which kind of polymer is used in the device.

Although detailed embodiments hâve been described, these only serve to provide a better understanding of the invention defined by the independent daims, and are not to be seen as limiting.

Claims (19)

1. A détection device fordetecting a marker in a liquid, comprising:

a reaction chamber, provided with a thermosensitive sensor, wherein said reaction chamber comprises an photopolymer capable of releasing or generating a chemical species that is capable of undergoing or initiating an exothermic or endothermie chemical reaction with amarker présent in the liquid.

2. The détection device according to claim 1, wherein the chemical species generated or released by the photopolymer is an acid, preferably a superacid.

3. The détection device according to claim 1 or 2, wherein the photopolymer is obtainable by photocuring a polymerizable composition comprising one or more polymerizable epoxy compounds with an excess of photoinitiator, and wherein the resulting photopolymer contains acid molécules from the decomposed photoinitiator absorbed in the bulk and/or on the surface of the photopolymer.

4. Thedetection device according to any of the preceding claims, further comprising any one of:

a substrate résistant to the liquid;

an injection chamber in communication with the reaction chamber exhibiting an inletfor introducingthe liquid; and an outlet, connected to the reaction chamber, to vent the hydraulic circuit.

5. Thedetection device accordingto any of the preceding claims, further comprising:

a heater element placed on a bottom layer suitable to heat and to evaporate the marker dissolved in the liquid, and to convey said vapor towards a thermosensitive sensor coated with an acidified photopolymer film, exhibiting acid molécules capable to promote an exothermic or endothermie chemical reaction with the marker vapor.

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6. Thedetection device according to any of the preceding daims, wherein the thermosensitive sensor is a pyroelectric sensor, and further comprises:

at least two conductive tracks transmitting the signais generated by the pyroelectric sensor to a current or voltage measurement device, preferably an oscilloscope.

7. Thedetection device according to any of the preceding daims, wherein a marker diluted in the liquid at a concentration smaller thanl50 ppm generates on the voltage measurement device a voltage greaterthan 1 mV.

8. Thedetection device according to any of the preceding daims, wherein the photopolymer is obtainable by a method comprising the following steps:

- a step of depositing a photocurable epoxy composition layer exhibiting an excess of photoinitiator on the walls and/or on the floor of the reaction chamber and/or on the thermosensitive sensor itself;

- a step of photocuring with UV radiation the photocurable epoxy composition layer exhibiting an excess of photoinitiator, so that exceeding unreacted acid molécules are left adsorbed in the bulk and/or on the surface ofthe acidified photopolymer layer.

9. Thedetection device according to any one of daims 3 to 8, wherein the photocurable epoxy composition comprises:

a) 20 to 50%wt of an epoxy monomer or oligomer, preferably an aromatic epoxy oligomer derived from a Novolac resin;

b) 5 to 60%wt, preferably 6 to 40%wt, more preferably 6 to 30%wt of a cationic photoinitiator, preferably a hexalfluoroantimonate or hexalfluorophosphate sait;

c) 10 to 30%wt of an organic solvent, preferably benzyl alcohol or tetrahydrofuran;

-2617962 based on the total weight of the photocurable composition.

10. Thedetection device according to any one of claims3 to 9, wherein the ratio epoxy équivalents / acid équivalents of the photocurable composition used to produce the acidified photopolymer is between 18 and 1.

11. The détection device according to any one of claims 1 to 9, wherein the liquid is a fuel and the marker is a diluted marker dissolved in said fuel.

12. A System comprising:

A. A détection device according to any of the preceding claims;

B. A fuel as said liquid;

C. A marker dissolved in the fuel with a concentration < 150 ppm, which is preferably an epoxy compound.

13. A method formanufacturing a détection device according to any one of steps 1 to 10 comprising the steps of:

depositing a photocurable epoxy composition layer exhibiting an excess of photoinitiator on the walls and/or on the floor of a reaction chamber and/or on a thermosensitive sensor placed in the reaction chamber;

photocuring with UV radiation the photocurable epoxy composition layer exhibiting an excess of photoinitiator, so that unreacted acid molécules resulting from the décomposition of the photoinitiator maintain in the bulk and/or on the surface of the acidified photopolymer layer.

14. The method according to claim 13, wherein the photocurable epoxy composition comprises:

a) 20 to 50%wt of an epoxy monomer or oligomer, preferably an aromatic epoxy oligomer derived from a Novolac resin;

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b) 5 to 60%wt, preferably 6 to 40%wt, more preferably 6 to 30%wt of a cationic photoinitiator, preferably a hexalfluoroantimonate or hexalfluorophosphate sait;

c) 10 to 30%wt of an organic solvent, preferably benzyl alcohol or tetrahydrofuran;

based on the total weight of the photocurable composition.

15. The method according to claim 13 or 14, wherein the ratio epoxy équivalents / acid équivalents of the photocurable composition used to produce the acidified photopolymer is between 18 and 1.

16. A method fordetecting a marker in a liquid, comprising the steps of:

introducing the marked liquidinto the reaction chamber of a detecting device according to any one of daims 1 to 11;

letting the marker react in the reaction chamber with a chemical species released or generated from the photopolymer to cause a température increase or decrease at the position of the thermosensitive sensor by an exothermic or endothermie reaction of the marker and the chemical species released or generated from the photopolymer; and measuring the voltage or current output generated by the thermosensitive sensor placed in the reaction chamber.

17. Themethod according to claim 16, wherein the liquid is a fuel and the marker is a diluted marker dissolved in said fuel.

18. The method according to any one of daims 15 to 17, wherein the liquid contains more than one marker, preferably two or three markers, the species released or generated by the photopolymer is able to cause a reaction with the more than one markers, and the obtained voltage and current output generated by the thermosensitive sensor is représentative for the presence and/or concentration of the more than one marker.

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19. The method according to any one of daims 15 to 18, wherein the chemical species released or generated from the photopolymer is an acid, preferably a superacid, and wherein the marker is a compound that reacts with the acid by ring-opening or polymerization, preferably a compound having one or more epoxy groups or a 5 compound having one or more ethylenically unsaturated groups.