WO2014041564A1

WO2014041564A1 - Covert security markers composition and authentication method

Info

Publication number: WO2014041564A1
Application number: PCT/IN2013/000553
Authority: WO
Inventors: Ashwinkumar Ramesh SHARMA; Premnath Venugopalan; Sangeeta Sunil HAMBIR
Original assignee: Council Of Scientific & Industrial Research
Priority date: 2012-09-12
Filing date: 2013-09-12
Publication date: 2014-03-20
Also published as: WO2014041564A4

Abstract

A new covert security feature for paper/polymeric substrates using a coating/marking ink which have sharp and distinct infra-red absorption is disclosed herein. Further, the invention discloses a method for incorporating the said security markers into the substrate and the use for authentication thereof.

Description

COVERT SECURITY MARKERS COMPOSITION AND

AUTHENTICATION METHOD

TECHNICAL FIELD OF INVENTION

The present invention relates to Covert infra-red security markers composition which serves as a covert security feature. Particularly, present invention relates to infra-red markers with sharp and distinct infra-red absorption. More particularly, present invention relate to a method for incorporating the said security markers into the substrate and the use for authentication thereof.

BACKGROUND OF THE INVENTION

Controlling the legitimacy and brand integrity of products in the era of globalization is becoming challenging to the governments and law enforcing organizations worldwide. Counterfeiting is observed in currencies, documents, arts and artifacts, software, toys, pharmaceutical and consumer products, electronics etc. Counterfeiting in drugs and food products wherein these counterfeit products are increasingly making their way into the public healthcare system have been identified as a threat to the public health by the Food and Drug Administration (FDA). One of the problems in addressing counterfeiting is that it can take different forms in the supply chain at the item-level or through diversion. For example, counterfeiting at the item level is observed in peripheral electronics equipment such as replaceable ink printer cartridges.

Industry world-wide has to bear huge financial losses due to counterfeiters. These losses not only affect the producers of genuine items, but they also involve social costs. Inadvertently, consumers are also the victims of this unfair activity. They receive poor-quality goods at an excessive price and are sometimes exposed to health and safety dangers. Governments lose out on unpaid tax and incur large costs in enforcing intellectual property rights.

l It is estimated that trade in counterfeit goods is now worth more than 5 per cent of world trade.

A number of factors can be attributed to the increased illegal trade such as advances in technology; increased international trade, emerging markets; and increased share of products that are attractive to copy such as branded clothing, branded vanity items, software etc.

Companies, governments and law enforcing agencies are becoming increasingly aware with regards to counterfeiting. Measures are now taken to adequately protect the genuine products and to implement effective anti- counterfeiting policies to deal with the menace. A great number of technologies such as holograms, biometric markers and inks, smart cards etc. are used to protect and authenticate the genuine products.

The security/authentication features can be of two types: a) Overt (visible feature), b) covert (hidden markers). The overt security features are visible to the naked eye and can be verified by a common person. The covert features are not visible to the naked eye and needs an authentication device/ method to verify that the feature exists. Both overt and covert security features have their usefulness and are used together to improve security of the product.

Examples of covert security features include special marking inks that can be printed on any type of substrate and appears only under certain conditions such as U.V or I.R.; embedded images, watermarks, laser coding, RFID (radio frequency identity tagging) and the like.

Special marking inks or chemical markers in general are the substances or a mixture of such substances which when incorporated or applied to an article renders specific properties distinguishing the articles and guaranteeing its identification. There are other chemical markers which have a distinct absorption in the IR region which is attributed to the different vibrational energy of the bonds, excited states in the molecule which determines their molecular structure. The use of chemical markers/ marking inks which show absorption in UV, Near infra- red regions are known in the art of which few are discussed below. US20110043789 relate to a method for marking and authenticating a security article such as a banknote, a document, a ticket, a foil, a thread, a label, a card, or a commercial good. Dyes and pigments which are useful for implementing the method and for making a printing ink or coating composition in said publication are selected from the group comprising cyanines (polymethines) and the related cyanin-type chromophores; quinones and the related quinone-type chromophores; porphines, phthalocyanines and the related macrocyclic chromophores; as well as heterosubstituted polycyclic hydrocarbon chromophores. Dyes 2, 3, 4, 5 disclosed in said publication have absorption maxima in the visible (425, 500, 575, 650 nm), and dyes 6,7,8,9,10 have absorption maxima in the IR (725, 800, 875, 950 and 1,025 nm wavelength). Dyes such as Hexadeca-(3-ethoxy-l-thiophenolato)-phthalocyanato- zinc(II) absorb in the region of 780 nm and Deca-(3-ethoxy-l-thiophenolato)-hexa-(3- methyl-l-thiophenolato)-phthalocy- anato-zinc(II) show absorption in the region of 850 nm.

US7070646 discloses an ink composition selected from the polymorph type X form of metal free phthalocyanine, the polymorph type Y form and Phase I & II forms of titanyloxy phthalocyanine, the polymorph Phase II form of vanadyloxy phthalocyanine, and the polymorph Phase V forms of hydroxygallium phthalocyanine and methoxygallium phthalocyanine having an absorption maximum in each of the near infra-red region from 700 to 1500 nm and visible region from 400 to 700 nm of the electromagnetic spectrum in a security method.

US5093147 relates to a method for providing intelligible markings that are virtually invisible to the unaided eye on the surface of an article, comprising: applying onto the surface, by a jet printing process, a marking medium comprising a compatible liquid or viscous substance containing an organic laser dye (typically IR- 125 in a concentration of about 0.005 to 0.05 percent by weight of the medium) that is poorly absorptive of radiation in the visible range of about 400 to 700 nanometers, is highly absorptive of radiation in the near infrared range of at least about 750 nanometers in wavelength (typically about 750 to 900 nanometers), and fluoresces in response to radiation excitation in the said near infrared range to produce fluorescent radiation of wavelengths longer than the wavelength of the excitation (typically in the range of about 800 to 1100 nanometers). Other useful laser dyes disclosed comprise DTTCI, DNTTCI, HDITCI, DDTTCI, IR-140, DDCI-4, or IR-132.

US20070281139 relate to a chemically reactive security ink, comprising: a solvent soluble dye, and a non-drying vehicle or ink base. The solvent soluble dye comprises a solvent soluble dye selected from the group of azo, xanthene, anthraquinone, triarylmethane, azine, thiazine, phthalocyanine, and metal complexes of the same. The articles which are protected include banknotes, cheques, credit cards, shares, passports, identity documents, driving licenses, entry tickets, revenue stamps, ID cards, travel tickets, postage stamps, packaging materials, seals, labels or articles of daily use.

US5723338 describe a method for tagging hydrocarbons and for detecting the presence of tagged hydrocarbons in a hydrocarbon mixture. The method is utilized to tag gasoline, diesel fuel, heating oil, lubricating oil or crude petroleum. The hydrocarbon to be tagged is blended with a relatively small amount of a fluorescent dye. The presence of the tagged hydrocarbon is subsequently determined by exciting the dye to fluoresce at wavelengths in the higher portion of the visible spectral region or the lower portion of the near infrared spectral region. The dye is selected from the group consisting of naphthalocyanine dye, phthalocyanine dye, cyanine dye, methine dye, croconium dye and squarylium dye. The dye is capable of absorbing radiation in an absorption band consisting of wavelengths of about 600 to about 2500 nanometers associated with a transformation to the excited state and emitting radiation in a fluorescent band consisting of wavelengths of about 600 to about 2500 nanometers associated with a return to the base state, and the excitation band overlapping the absorption band at an appropriate intensity to transform a significant portion of the dye from the base state to the excited state. EP0509818 relates to Liquid petroleum products that are marked with markers having the general formula:

wherein the groups Rl and R2 are the same or different and each represents hydrogen or a C1-C7 alkyl group, provided that at least one, and preferably both, groups Rl are C3-C7 alkyl; and wherein the groups R3 are the same or different and each represents -H, -N02, -CI, -Br, -F, -CN, and -Me, provided that at least one R3 is selected from - N02, -CI, -Br, -F, and -CN. The markers may be detected in the petroleum products by extraction with a reagent comprising water and a water-soluble amine, and, preferably a water-miscible co solvent. This reagent system not only extracts the marker from the liquid petroleum product, but causes the marker to react or complex, producing a clearly defined color that identifies the petroleum product as to source, permitted use, etc.

Covert security features such as use of marking inks though are very valuable investigative tool, counterfeiters may be able to copy many of the simpler features unless they are applied skillfully and their details are kept secret. Hence there remains a continuous need to provide solutions to curb the ever growing fraud in counterfeiting of products.

Infra-red difference spectra usually contain many different bands indicating the wealth of information that is encoded in the spectrum. However, extracting information is often difficult and requires a characteristic conformational change in the spectrum that can be used to detect and define the transient conformational states in the chemical compounds. There are a vast majority of chemical substances that exhibit fundamental vibrational absorption bands in the mid-infrared spectral region and the absorption of light by these fundamental bands can provide a means for their detection. While the prior art has explored IR markers as security features, security features based IR markers in the range of 1800-2500 cm^"1 have been overlooked and are thus novel. We further find that markers in this IR rane surprisingly give very high sensitivity and selectivity at extremely low and hence non toxic concentrations and at very high detection speeds, which has hitherto not been possible with IR markers known in the art and other novel IR markers.

In view of the above, the present inventor felt a need to explore chemical molecules as novel marking inks which can show distinct absorption in the mid infra- red region and would be helpful for mapping of the samples to overcome counterfeiting.

OBJECTS OF THE INVENTION Main object of the present invention is to provide unique chemical marker composition that show characteristic absorption in mid infra-red beamline as new covert security feature which can be easily detected through an authentication device. Another object of the present invention is to provide IR markers which are stable, non- hazardous, cheap which can be incorporated in paper, paper pulp, ink, varnish etc. and can also be included in the coating to identify/detect a variety of commercial and security products.

Yet another object of the present invention is to provide a method for incorporating the said security markers into the substrate and the use for authentication thereof.

SUMMARY OF THE INVENTION

Accordingly, present invention provides a composition comprising 0.1-70% of one or more covert security marker compounds selected from compound of general formula (I),

General formula I

Wherein, 'A' represents a phenyl group or an alkali metal or heteroaryl group; R_\ and R₂ are selected independently of each other from hydrogen, halogen, - OH, - N0₂, -COOH, -CH₂Br, -C≡C-Br;

R3 represents -C≡N or N^"=N⁺=N^"; with the provisio, when R₃ is N^~=N⁺=N^~, A is an alkali metal; When R₃ is C≡N, A represents phenyl or heteroaryl group which may be substituted or unsubstituted β-alanine or potassium ferri cyanide along with 30-99.9% acceptable ingredients characterized by having at least one sharp and distinct infra-red absorption in wave number region 1800-2500 cm^"1 for identification and authentication of articles, such that the authentication is possible accurately in less than five scans.

In yet another embodiment of the present invention, the marker compounds are selected from a group of substituted benzonitriles of general formula (II),

Formula II

Wherein, Rl and R2 are selected independently of each other from hydrogen, halogen, -OH, -N02, -COOH, -CH2Br.

In yet another embodiment of the present invention, representative compounds of formula 1 comprises:

i. 4-chloro-3-nitrobenzonitrile;

ii. 3-(Bromomethyl)benzonitrile;

iii. Sodium Azide;

iv. 4-Hydroxybenzonitrile; v. 3-Bromo, 4-hydroxybenzonitrile;

In yet another embodiment of the present invention, acceptable ingredients is selected from the group consisting of resins, inks, surfactants, thinners, binders and such like.

In yet another embodiment of the present invention, the IR marker compounds are used either alone or in combination thereof. In yet another embodiment of the present invention, the covert security marker compounds are incorporated into the article or are applied on to the article for identification and authentication of articles.

In yet another embodiment of the present invention, the method for authenticating an article comprises steps of;

a. providing fine powder of IR marker compounds , which when exposed to radiation in wave number region 1800-2500 cm^"1 exhibits at least one peak at said wave number in the IR region, wherein at-least one of said peaks define a signature for authentication;

b. mixing said IR marker(s) with acceptable ingredients wherein said ingredients does not show absorption in the said IR region;

c. coating the mixture as obtained in step (b) uniformly on to the article to be authenticated using Doctor blade method;

d. injecting ink loaded with the IR marker(s) in an empty cartridge of an inkjet printer used to print on paper; or

e. injecting ink loaded with the IR marker(s) in an empty cartridge of an inkjet printer;

f. analyzing said marker(s) using a micro Attenuated Total reflection (ATR)-FTIR to determine the existence of said signatures to authenticate the said article. In yet another embodiment of the present invention, use of covert security marker compounds characterized in having at least one sharp and distinct infra-red absorption in wave number region 1800-2500 cm^"1 for identification and authentication of products/articles wherein said security markers are selected from compound of general formula (I), β-alanine or potassium ferri cyanide

General formula I

Wherein, 'A' represents a phenyl group or an alkali metal or heteroaryl group; Ri and R₂ are selected independently of each other from hydrogen, halogen, - OH, - N0₂, -COOH, -CH₂Br, -C≡C-Br;

R₃ represents -C≡N or N^"=N⁺=N^"; with the provisio, when R₃ is N^"=N⁺=N^", A is an alkali metal; When R₃ is C≡N, A represents phenyl or heteroaryl group which may be substituted or unsubstituted.

In yet another embodiment of the present invention, method for identification and authentication of an article/ products comprising incorporating covert security markers characterized by having a sharp and distinct infra-red absorption in wave number region 1800-2500 cm-1 into the article/product or applying the markers on to the article/product.

In yet another embodiment of the present invention, concentration of the covert security markers in the range of 0.1-70% that may be incorporated or may be applied onto the article/product for identification and authentication. BRIEF DESCRIPTION OF THE FIGURES

Figure la-lg: shows Attenuated Total reflection (ATR) spectrum of molecules of invention to be used as IR markers.

Figure 2a and 2b: ATR spectrum of paper coated with IR transparent resin. Figure 3a-3f: ATR for authentication of paper coated with resin loaded with IR markers.

Figure 4a and 4b: ATR of coating of paper with resin loaded with two IR markers. Figure 5a-5e: Loading of IR markers in printing ink followed by printing.

Figure 6a-6c: Loading of two IR markers in printing ink followed by printing.

Figure 7: Coating of Polymeric substrate with resin loaded with two IR markers.

DETAILED DESCRIPTION OF THE INVENTION DEFINITIONS

Sharp and distinct peak: A peak that is distinct and sharp and covers at least 80% of scale of Y axis in an IR spectrum.

In the process of exploring chemical molecules that would be useful as markers for detecting counterfeiting, the inventors have found molecules that exhibit unique IR absorption spectrum in the mid infra red region.

The present invention relates to a new covert security feature for paper/polymeric substrates using a coating/marking inks which have sharp and distinct infra -red absorption and to a method for incorporating the said security markers into the substrate and the use for authentication thereof.

Accordingly, the present invention relate to stable, cheap non-hazardous covert security markers of formula (I) with a sharp and distinct infra-red absorption in wave number region 1800-2500 cm-1 for identification and authentication of articles;

Formula I

Wherein, 'A' represents a phenyl group or an alkali metal or heteroaryl group; Ri and R₂ are selected independently of each other from hydrogen, halogen, -OH, -

N0₂, -COOH, -CH2Br. R₃ represents -C≡N or N^"=N =N^";

With the proviso that, when R3 is N^"=N⁺=N^", A is an alkali metal;

When R3 is C≡N, A represents phenyl or heteroaryl group which may be substituted or unsubstituted.

The invention provides IR markers of compounds of formula I encompasses substituted benzonitriles of formula (II).

Formula II

The IR marker compounds of formula I encompasses sodium azide.

The present invention provides stable, cheap non-hazardous IR markers selected from a group of substituted benzonitriles, or heteronitriles or sodium azide that may be used in the concentration range of 10-70%, with a sharp and distinct infra-red absorption in wave number region 1800-2500 cm^"1 as covert security feature for identification and authentication of articles.

The General strategy disclosed includes the following steps:

1. Identify molecules that produce strong and stable (do not change with time or exposure to environment etc) IR signatures between 1800-2500 cm-1.

2. Screening for molecules includes checks for:

a. Strong and sharp IR signature (high signal to noise ratio at reasonable concentration used; can be machine authenticated)

b. Stability with respect to UV, moisture, temperature (say, 45C) c. Safety and non-hazardous nature d. Suitable form (solid/liquid) for specific method of use and/or convertible to suitable form

e. Should not leach or dissolve out.

3. Place one or more of the selected molecules on the printed paper note or a part of it by a suitable method such that it produces a unique IR signature in the form of one or more bands (Bl, B2, etc) of intensities (II, 12 etc).

4. Change combinations to get different signatures.

5. Develop an authentication method to detect the presence or absence of the unique IR signature.

On the basis of above, the present invention provides the following novel IR markers which have a sharp and distinct IR band in the region 1800-2500 cm-1 which defines the signature of authentication.

Table 1

The said IR markers can be used alone or in combination thereof and may be incorporated into the article or may be applied on to the article for authentication. The said IR markers can be incorporated in paper, paper pulp, ink, varnish etc. and can also be included in the coating to identify/detect a variety of commercial and security articles such as banknotes, cheques, credit cards, shares, passports, identity documents, driving licenses, entry tickets, revenue stamps, ID cards, travel tickets, postage stamps, packaging materials, seals, labels or articles of daily use to provide for an easy authentication of said article using authentication device. The said IR markers may be incorporated in other products for detection of adulteration, mixing or adding impurities or diluting products, thus affecting their economic value or affecting safety of the products. The IR markers of the invention provide a rugged, reliable, selective, sensitive, precise and accurate method of detecting counterfeiting, in a substantially fool proof manner.

Further, the IR markers may be optionally combined with other known methods of detecting counterfeiting.

The mid-infrared (mid-IR) spectral region is a key area in the infra-red spectroscopy because of its specific sensitivity for the organic functional group, such as C=0, C=C, C— H, C≡C, or O— H, -C≡N, that absorbs infrared radiation. In that range occur most of the fundamental molecular vibrations and many of the first overtones and combinations. The bands in the mid-infrared tend to be sharp and have very high absorptivity' s, with both characteristics being desirable. Because the bands are sharp, most small molecules have distinctive spectral "fingerprints" that can be readily identified in mixtures. Also, because individual peaks can often be associated with individual functional groups, it is possible to see changes in the spectrum of an individual reagent due to a specific chemical reaction. The mid-infrared absorption spectrum of a compound is thus very specific for that compound.

Present invention discloses the method for loading of IR markers in the printing ink. Accordingly, IR marker molecule is taken and crushed using a mortar and pestle to a fine powder. The fine powder (Sample 5 A - 10 wt% and Sample 5B-20 wt%) are mixed with an ink selected from Magenta; Flow Jet+ Water Based Die Ink; etc that are IR transparent ink in the region 1800-2500cm- 1. The ink loaded with the IR marker is further injected in an empty cartridge of an inkjet printer which is then used to print on A4 Modi Xerox paper. Present invention provides a method for coating of IR markers on to the substrate. The process includes crushing the IR markers (either alone or mixture thereof) using a mortar and pestle to a fine powder. This is followed by mixing the powdered IR markers with a transparent resin (i.e. transparent in the region of 1800- 2500cm- 1 ) and uniformly coating on the article using doctor blade method.

The IR transparent resin (transparent in 1800-2500cm-l region) is prepared using the mixture of DOS A (Dodecenyl succinic anhydride), Embed 812, NMA (NADIO Methyl anhydride), 2,4,6 (tri(dimethylaminoethyl)phenol) which is commercially available. IR transparent resin (transparent in 1800-2500cm-l region) is further diluted using toluene in order to reduce the viscosity and curing time of the resin.

The present invention discloses a method for authenticating an article including the following steps:

1. providing fine powder of IR markers, which when exposed to radiation in wave number region 1800-2500 cm^"1 emits at least one peak at said wave number in the IR region, wherein at-least one of said peaks define a signature for authentication;

mixing said IR markers with transparent resin/ink wherein the transparent resin/ink does not show absorption in the said IR region;

uniformly coating the said mix of step (2) on to the article to be authenticated using Doctor blade method; or

injecting ink loaded with the IR marker in an empty cartridge of an inkjet printer used to print on A4 Modi Xerox paper; and

Analyzing said markers using a micro ATR-FTIR to determine the existence of said signatures to authenticate the said article.

The present invention relates to the use of IR markers either alone or combination thereof with a sharp and distinct absorption in the infra- red region wave number 1800-2500 cm^"1 for identification and authentication of articles. From the foregoing description and following examples, it is evident that the present invention has successfully provided novel chemical molecules as IR markers with a sharp and distinct absorption in the wave number region 1800-2500 cm-1 as covert security feature for authentication of the objects/articles. The chemical molecules identified as IR markers in the instant invention are cheap, stable with respect to UV, moisture, temperature (45°C), is non-hazardous in nature, can be provided in suitable form (solid/liquid) for specific method of use and/or convertible to suitable form and do not leach or dissolve out. Further, they can be applied either alone or in combination thereof and may be applied on to the object/article or injected into the object/article by the methods described above and produces a unique IR signature in the form of one or more bands of variable intensities thereby authenticating the genuinity of the object article. EXAMPLES

Following examples are given by way of illustration therefore should not be construed to limit the scope of the invention.

Example 1: Attenuated Total reflection (ATR) of markers

Table 2

The above table and figures 1 a-f indicates that the above molecules show a IR absorption in the region 1800-2500 cm-1.

Example 2

Coating of paper with resin that is IR transparent in 1800-2500cm-l

An IR transparent resin (transparent in 1800-2500cm-l region) was prepared using the mixture of lgm of DOS A (Dodecenyl succinic anhydride), 0.5 gm of Embed 812, 0.5 gm of NMA (NADIO Methyl anhydride), 0.01 gm of 2,4,6 (tri(dimethylaminoethyl)phenol) which is commercially available. IR transparent resin (transparent in 1800-2500cm-l region) was then diluted using 1 ml toluene. Now the resin was uniformly coated on paper using Doctor Blade in order to maintain the thickness of the resin coating 100 μ. It was verified that the coating does not absorb IR at 1800-2500 cm-1. An IR transparent resin (transparent in 1800-2500cm-l region) was prepared using the Phenol formaldehyde resin from Abilin Polymers in powder form was purchased. Viscous PF resin can be obtained by mixing powdered resin with the methanol(solvent) in the ratio of 2:1 wt%. Now the resin was uniformly coated on paper using Doctor Blade in order to maintain the thickness of the resin coating 100 μ. It was verified that the coating does not absorb IR at 1800-2500 cm- 1.

Example 3

Coating of paper with resin loaded with IR markers

IR marker molecules were taken and crushed in a mortar and pestle to a fine powder. The fine powder was mixed well with the IR transparent resin (transparent in 1800-2500cm-l region) as described in Example 2 in the proportion shown below.

Table 3

Further processing and coating was done as described in Example 2. Example 4

Authentication of paper coated with resin loaded with IR markers

The coated samples (3A, 3B, 3C, 3D and 3E ) was scanned for IR absorption using an ATR-FTIR. The relevant IR absorptions are shown in Figures 3a, 3b, 3c, 3d, 3e and 3f.

Table 4

The above figures indicate that the selected IR markers show a sharp, distinct signal in the region 1800-2500 cm-1 as shown in the table below.

Table 5

Example 5

Coating of paper with resin loaded with two IR markers

Two IR marker molecules (Sodium Azide and 4-Hydroxybenzonitrile) were taken, crushed and sieved using a 105 micron sieve to maintain particle size of markers. The fine powder was mixed well with the ER. transparent resin (transparent in 1800-2500cm-l region) described in Example 2 in the proportion as given in the table below.

Table 6 Sample Loaded IR Concentration % w/w Spectra number Marker

4A SA and 4HBN 25% each Figure 4a

4B SA and 4HBN SA-35% Figure 4b

4HBN-15%

The above figures indicate that the selected two IR markers show a sharp, distinct pattern in the region 1800-2500 cm-1. Also, the peak intensities vary with % Concentration Example 6

Loading of IR markers in printing ink followed by printing

IR marker molecule was taken and crushed using a mortar and pestle to a fine powder. The fine powder of markers stated in table7 was mixed with an ink (Color: Magenta; FlowJet+ Water Based Die Ink; Supplier: Jet Catridges (I) Pvt Ltd, Mumbai, India) that was IR transparent ink in the region 1800-2500cm-l. This ink loaded with the IR marker was injected in an empty cartridge of an inkjet printer. The ink loaded with the IR marker was then used to print on A4 Modi Xerox paper.

Table 7

The above figures indicate that the selected IR markers mixed with ink shows a single sharp, distinct signal in the region 1800-2500 cm- 1.

Example 7

Loading of two IR markers in printing ink followed by printing

Following sets of IR marker molecule were taken and Samples were prepared as explained in example no. 6

Table 8

The above figures indicates that the selected IR markers mixed with the ink shows the two sharp, distinct signals in the region 1800-2500 cm-1.

Example 8

Coating of Polymeric substrate with resin loaded with two IR markers.

Samples were prepared with two IR markers as given in table 9 and were coated on polymeric substrate (PP sheet) using method described in example 2 Two IR marker molecules (Sodium Azide and 4-Hydroxybenzonitrile) were taken and crushed and sieved using a 105 micron sieve to maintain particle size of markers. The fine powder was mixed well with the IR transparent resin (transparent in 1800- 2500cm- 1 region). IR transparent resin (transparent in 1800-2500cm-l region) was prepared using the mixture of DOS A (Dodecenyl succinic anhydride), Embed 812, NMA (NADIO Methyl anhydride), 2,4,6 (tri(dimethylaminoethyl)phenol) which is commercially available. IR transparent resin (transparent in 1800-2500cm-l region) was then diluted using toluene in order to reduce the viscosity and curing time of the resin. Now the resin was uniformly coated on polymeric substrate (PP sheet) using Doctor Blade in order to maintain the thickness of the resin coating. It was verified that the coating does not absorb IR at 1800-2500 cm-1. Table 9

The presence of peak (1800-2500 cm-1) in the figure indicates that the IR markers can be used on Polymeric substrates.

Example 9

Fast detection method for Authentication of paper embedded with resin loaded with IR markers Fast detection of paper embedded with resin loaded with IR markers was done by FT-IR ( ATR mode), Bruker instrument using macros. The macro programming was designed as per requirements like capturing spectra, baseline correction, smoothening of spectra, evaluating, quick comparing the reference and sample spectra and displaying result for Authentic (OK) or Fake (NOT OK).

First reference sample was scanned in the range of 2250 cm-1 to 2050 cm-1. The obtained spectra pattern was set as a reference and was loaded as reference pattern in macros for quick compare between reference and the sample to be tested as Authentic or fake. So for the fast (within 30 Sec.) detection of sample, we execute macros as function which follows the no. of steps and parameters and apply it to the sample spectra and at last compares the reference spectra with that of sample spectra and displays the result as Authentic (OK) or Fake (NOT OK). For the best and fast Authentication the co-relation function between reference and sample spectra was set to the 80%.

Example 10

Authentication of paper printed with magenta ink loaded with Congo red dye as IR marker-Comparative example

Congo red dye with two different concentrations (3.3% and 10%) was prepared in magenta ink and was printed on A4 paper and was scanned from 1575 cm-1 to 1630 cm-1 which correspond to N=N open chain azo group of Congo red dye. Now, 20 samples of each concentration were tested for N=N peak using macros in ATR mode as explained in example -9

Table 10

In the table above Positive 20/20 is a condition which indicates that the reference spectra is identical to the sample spectra at the same cone, using macros defined in example 9. Negative 20/20 indicates the reference spectra is not at all identical to the sample spectra. For both the cone. (3.3%, 10% w/w) Congo red dye shows low sensitivity and specificity as IR marker.

Example 11

Authentication of paper printed with magenta ink loaded with Sudan III dye as IR marker Comparative example

Sudan III dye with two different concentrations (3.3% and 10%) was prepared in magenta ink and was printed on A4 paper and was scanned from 1400 cm-1 to 1600 cm-1 which correspond to N=N open chain azo group of Sudan III dye. Now, 20 samples of each concentration were tested for N=N group using macros in ATR mode as explained in example -9

Table 11

Above table shows low sensitivity and specificity of Sudan III dye as IR marker. Example 12

Authentication of paper printed with magenta ink loaded with sodium Azide and 4-hydroxybenzonitrile as IR marker

Sodium azide and 4-Hydroxybenzonitrile were mixed together with two different concentrations (3.3% each and 10% each), prepared in magenta ink and were printed on A4 paper and was scanned from 2250 cm-1 to 2050 cm-1 which correspond to azide group of Sodium azide at 2100 cm-1 and nitrile group of 4Hydroxybenzonitrile at 2230 cm-1. Now, 20 samples of each concentration were tested for azide and nitrile group using macros in ATR mode as explained in example -9

Table 12

Blank (only 3.3% w/w each i.e. 10% w/w each i.e. SA, magenta ink on A4 SA, 4HBN, Mixed 4HBN, Mixed with paper) with magenta ink, magenta ink, Printed on

Printed on A4 paper A4 paper

Positive 20/20 19/20 20/20

Negative 0/20 1/20 0/20 Above table shows High sensitivity and specificity of two marker (from 1800 - 2500 cm-1) used as IR marker. Thus with reference to tables 10, 11 and 12 it is observed that when the scans are carried out for Congo Red and Sudan III, surprisingly the probability of false negative as well as false positive for low concentrations of the dyes is very high, whereas surprisingly in the IR markers of the invention, at low concentrations also, the probability of obtaining precise, accurate, specific and sensitive results is high. Example 13

Authentication of paper printed with magenta ink loaded with Potassium hexacyanoferrate(III) and Beta- Alanine as IR marker

Potassium hexacyanoferrate(III) and Beta-Alanine were mixed together with two different concentrations (20% each and 40% each), in magenta ink. A4 paper was printed with this ink and scanned from 2300 cm-1 to 1900 cm-1. Potassium hexacyanoferrate(III) shows peak at 2077 cm-1 and Beta-Alanine shows peak at 2207 cm-1. Then, 20 samples were tested using macros in ATR mode with 1 no. of scan

Table 13

Above table shows high sensitivity and specificity of two marker (from 1800 - 2500 cm-1) used as IR marker. This example also illustrates ability to get accurate results with just one scan, thus allowing high speed of detection

Example 14

Fast detection method for Authentication of paper embedded with Resin/Ink loaded with IR markers at Single Scan

Fast detection of paper embedded with resin/Ink loaded with IR markers was done by FT-IR ( ATR mode), Bruker instrument using macros. The macro programming was designed as per requirements like capturing spectra, baseline correction, smoothening of spectra, evaluating, quick comparing the reference and sample spectra and displaying result for Authentic (OK) or Fake (NOT OK).

First reference sample was scanned at single scan in the range of 2500 cm-1 to 1800 cm-1. The obtained spectra pattern was set as a reference and was loaded as reference pattern in macros for quick compare between reference and the sample to be tested as Authentic or fake. So for the fast (within 5 Sec.) detection of sample, we execute macros as function which follows the no. of steps and parameters and apply it to the sample spectra and at last compares the reference spectra with that of sample spectra and displays the result as Authentic (OK) or Fake (NOT OK). For the best and fast Authentication the co-relation function between reference and sample spectra was set to the 95%. This example also illustrates ability to get accurate results with just one scan, thus allowing high speed of detection. Example 15

Authentication of paper coated with resin that is IR transparent in 1800-2500cm- 1 loaded with IR marker and

An example of an IR transparent resin (transparent in 1800-2500cm-l region) was prepared using the Phenol formaldehyde resin from Abilin Polymers in powder form was purchased. Viscous PF resin can be obtained by mixing powdered resin with the methanol (solvent) in the ratio of 2:1 wt%. Therefore the resin loaded with IR marker was prepared by taking the IR marker soluble in the methanol; the formulation was made by taking 0.8gm of powder PF resin which was readily soluble in 0.4mg of methanol already containing 0.2 gm 4HBN as IR marker. The obtained viscous resin was coated uniformly on the paper using foam and was authenticated as explained in the example 14

Table 15

ADVANTAGES OF INVENTION

• IR markers in the wave number 1800 - 2500 cm-1 that can be detected at high speeds with respect to high sensitivity and high selectivity, thus allowing fast and error free counterfeit detection

• The markers are cheap, stable with respect to UV, moisture, temperature (45°C) and non-hazardous in nature.

• The markers can be provided in forms suitable for end use.

Claims

A composition comprising 0.1-70% of one or more covert security marker compounds selected from the group comprising of compound of general formula (I)

General formula I

Wherein, Ά' represents a phenyl group or an alkali metal or heteroaryl group;

R and R₂ are selected independently of each other from hydrogen, halogen, -OH, -N0₂, -COOH, -CH₂Br, -C≡C-Br;

R₃ represents -C≡N or N^~=N⁺=N^"; with the provisio, when R₃ is N^" =N⁺=N^", A is an alkali metal; When R₃ is C≡N, A represents phenyl or heteroaryl group which may be substituted or unsubstituted.

β-alanine or potassium ferri cyanide along with 30-99.9% acceptable ingredients characterized by having at least one sharp and distinct infra-red absorption in wave number region 1800-2500 cm^"1 for identification and authentication of articles, such that the authentication is possible accurately in less than five scans.

The covert security marker composition according to claim 1, wherein the representative compounds of are selected from a group of substituted benzonitriles of general formula (II)

Formula II

Wherein, RI and R2 are selected independently of each other from hydrogen, halogen, -OH, -N02, -COOH, -CH2Br.

3. The composition as claimed in claim 2, wherein representative compounds of formula I comprises:

i. 4-chloro-3-nitrobenzonitrile;

ii. 3-(Bromomethyl)benzonitrile;

iii. Sodium Azide;

iv. 4-Hydroxybenzonitrile;

v. 3-Bromo, 4-hydroxybenzonitrile;

vi. Potassium ferricyanide;

vii. Beta-alanine.

4. The covert security marker composition as claimed in claim 1, wherein acceptable ingredients is selected from the group consisting of resins, inks, surfactants, thinners, binders and such like.

5. The covert security marker composition as claimed in claim 1, wherein the ER markers are used either alone or in combination thereof.

The covert security marker composition according to claim 1, wherein the covert security marker compounds are incorporated into the article or are applied on to the article for identification and authentication of articles.

The covert security markers composition according to claim 1, wherein the method for authenticating an article comprises steps of;

a. providing fine powder of IR marker compounds, which when exposed to radiation in wave number region 1800-2500 cm^"1 exhibits at least one peak at said wave number in the IR region, wherein at-least one of said peaks define a signature for authentication;

b. mixing said IR marker(s) with acceptable ingredients wherein said ingredients does not show absorption in the said IR region; c. coating the mixture as obtained in step (b) uniformly on to the article to be authenticated using Doctor blade method; d. injecting ink loaded with the IR marker(s) in an empty cartridge of an inkjet printer used to print on paper; or

f. analyzing said marker(s) using a micro Attenuated Total reflection

(ATR) -FTIR to determine the existence of said signatures to authenticate the said article.

Use of covert security marker compounds characterized in having at least one sharp and distinct infra-red absorption in wave number region 1800-2500 cm^"1 for identification and authentication of products/articles wherein said security markers are selected from compound of general formula (I), β-alanine or potassium ferri cyanide

General formula I

Wherein, 'A' represents a phenyl group or an alkali metal or heteroaryl group; Ri and R₂ are selected independently of each other from hydrogen, halogen, - OH, -N0₂, -COOH, -CH₂Br, -C≡C-Br;

9. The use according to claim 8, wherein covert security markers may be used either alone or in combination thereof.

10. A method for identification and authentication of an article/ products comprising incorporating covert security markers characterized by having a sharp and distinct infra-red absorption in wave number region 1800-2500 cm- 1 into the article/product or applying the markers on to the article/product.

11. The method according to claim 10, wherein the covert security markers may be used either alone or in combination thereof. 12. The method according to claim 10, wherein the concentration of the covert security markers in the range of 0.1-70% that may be incorporated or may be applied onto the article/product for identification and authentication.