USOO8002851B2

(12) United States Patent (10) Patent No.: US 8,002,851 B2 Fyvie et al. (45) Date of Patent: Aug. 23, 2011

(54) THERMOCHROMIC INKAND COATING 2003/0081521 A1 5/2003 Solomon et al. COMPOSITIONS 2004/0022542 A1 2/2004 Atkinson 2004.0054594 A1 3/2004 Forster et al. 2004/0083377 A1 4/2004 Wu et al. (75) Inventors: Thomas Joseph Fyvie, Schenectady, NY 2005.0005285 A1 1/2005 Olson et al. (US); David Gilles Gascoyne, 2005, 0110978 A1 5/2005 Potyrailo et al. Niskayuna, NY (US); Andrea Jeannine 2005.016751.0 A1 8/2005 Potyrailo et al. 2006/0005326 A1 1/2006 Rollat-Corvol et al...... 8/405 Peters, Clifton Park, NY (US); Marc 2006/0028924 A1 2/2006 Atkinson Brian Wisnudel, Glen Rock, NJ (US) 2006/0040400 A1 2/2006 Mizutani et al...... 436,63 (73) Assignee: NBCUniversal Media LLC, New York, (Continued) NY (US) FOREIGN PATENT DOCUMENTS (*) Notice: Subject to any disclaimer, the term of this JP O51593.65 A 6, 1993 patent is extended or adjusted under 35 (Continued) U.S.C. 154(b) by 343 days. OTHER PUBLICATIONS (21) Appl. No.: 12/403,930 Dr. Patrick Collins; “Equatorial Times No. 3'; The Newsletter of the SPS 2000 Community Around the World, Dec. 1996. Available at (22) Filed: Mar 13, 2009 http://www.spacefuture.com/power/equatorialtimes/3.shtml. (65) Prior Publication Data (Continued) US 2010/O234504 A1 Sep. 16, 2010 Primary Examiner — Lorna M Douyon (51) Int. Cl. Assistant Examiner — Tri V Nguyen C09D II/00 (2006.01) (74) Attorney, Agent, or Firm — Fletcher Yoder (52) U.S. Cl...... 8/506; 8/522; 8/638; 106/31.13; 106/31.27; 106/31.96 (57) ABSTRACT (58) Field of Classification Search ...... 8/506, 522, A thermochromic ink composition comprises at least one 8/638; 106/31.13, 31.27, 31.96 thermochromic optical-state change material, at least one See application file for complete search history. thermally responsive pH modifier, and at least one base and at least one binder material. The quantity of the thermally (56) References Cited responsive pH modifier is less than or equal to about 0.25 milli moles based on the amount of optical-state change mate U.S. PATENT DOCUMENTS rial. The ink composition is capable of transforming from a 5,527,385 A * 6/1996 Sumii et al...... 106.31.17 first optical state to a second optical state upon exposure to a 6,090,193 A * 7/2000 Nigam et al...... 106.31.27 thermal stimulus. The thermochromic ink composition may 6,139,779 A * 10/2000 Small et al...... 252/583 comprise a nitro dye. A thermochromic coating composition 6,783,991 B1* 8/2004 Mehta et al...... 436,164 6,790,501 B2 9/2004 Van de Grampel et al. formed using the thermochromic ink composition is also 6,795,464 B2 9/2004 Lawandy disclosed. 7,227.445 B2 6, 2007 Atkinson 2002fO163479 A1 11, 2002 Lin et al. 17 Claims, 2 Drawing Sheets 11 100 110

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U.S. PATENT DOCUMENTS WO WO2004/070718 A1 8, 2004 2006/0234003 A1 10, 2006 Selinfreund WO WO2007061774 A1 5/2007 WO WO2007061974 A1 5/2007

2007/0.142502 A1* 6/2007 Zhu et al...... 523, 161 2007/0240607 A1* 10, 2007 Vincent Kwan et al. ... 106.31.16 2009.0036304 A1 2/2009 Misner et al...... SO3,201 OTHER PUBLICATIONS FOREIGN PATENT DOCUMENTS WO Search Report, PCT/US2007/77230, Apr. 16, 2008. WO WO98,40930 A1 9, 1998 WO WO9967085 A 12/1999 * cited by examiner U.S. Patent Aug. 23, 2011 Sheet 1 of 2 US 8,002,851 B2

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20 US 8,002,851 B2 1. 2 THERMOCHROMIC INKAND COATING responsive pH modifier, and at least one base and at least one COMPOSITIONS binder material. The quantity of the thermally responsive pH modifier is less than or equal to about 0.25 milli moles based BACKGROUND on the thermochromic optical-state change material. The thermochromic ink composition is capable of transforming The invention includes embodiments that relate to a ther from a first optical state to a second optical state upon expo mochromic ink composition. More particularly, the invention Sure to a thermal stimulus. includes embodiments that relate to a thermochromic ink Another embodiment of the invention is directed to a ther composition and a thermochromic coating composition for mochromic ink composition comprising at least one thermo use as part of an anti-theft system for optical articles. 10 chromic optical-state change material consisting of sodium Shoplifting is a major problem for retail venues and espe salt of bromothymol blue, at least one thermally responsive cially for shopping malls, where it is relatively difficult to pH modifier, and at least one base and at least one binder keep an eye on each customer while they shop or move around material. The quantity of the thermally responsive pH modi in the store. Relatively small objects, such as CDs and DVDs are common targets as they can be easily hidden and carried 15 fier is less than or equal to about 0.25 milli moles based on the out of the shops without being noticed. Shops, as well as the thermochromic optical-state change material. The thermo entertainment industry, incur monetary losses because of chromic ink composition is capable of transforming from a Such instances. first optical state to a second optical state upon exposure to a Even though closed circuit Surveillance cameras may be thermal stimulus. located at such places, theft still occurs. Retail products Another embodiment of the invention is directed to a ther Sometimes are equipped with theft-deterrent packaging. For mochromic ink composition comprising at least one thermo example, clothing, CDs, audiotapes, DVDs and other high chromic optical-state change material, at least one nitro dye value items are occasionally packaged along with tags that set having a Formula I: off an alarm if the item is removed from the store without being purchased. These tags are engineered to detect and alert 25

for shoplifting. For example, tags that are commonly used to secure against shoplifting are the Sensormatic(R) electronic article Surveillance (EAS) tags based on acousto-magnetic technology. RFID tags are also employed to trace the items on store shelves and warehouses. Other theft-deterrent technolo 30 gies currently used for optical discs include hub caps for DVD cases that lock down the disc and prevent it from being ON ON NO2 removed from the packaging until it is purchased, and “keep ers' that attach to the outside of the DVD case packaging to prevent the opening of the package until it is purchased. In 35 wherein R comprise hydrogen oran alkyl group having 1 to 8 Some cases, retailers have resorted to storing merchandise in carbon atoms, at least one thermally responsive pH modifier, locked glass display cases. In other stores, the DVD cases on at least one base, and at least one binder material; wherein the the shelves are empty, and the buyer receives the actual disc quantity of the thermally modified pH modifier is less than or only when purchased. Many of these approaches are unap equal to about 0.25 milli moles based on the amount of pealing because they add an additional inconvenience to the 40 optical-state change material; and wherein the thermochro buyer or retailer, or they are not as effective at preventing theft mic ink composition is capable of transforming from a first as desired. Optical storage media, in particular, pose an addi optical state to a second optical state upon exposure to a tional problem in that their packaging and the sensor/anti thermal stimulus. theft tags may be easily removed. Another embodiment of the invention is directed to a ther Therefore, there is a continued need to provide techniques 45 mochromic ink composition comprising at least one thermo and systems that can assist in reducing the incidence of, and chromic optical-state change material consisting of sodium damage caused by, Stolen media. salt of bromothymol blue, at least one nitro dye having a Formula I, wherein R comprise hydrogen or an alkyl group BRIEF DESCRIPTION OF FIGURES having 1 to 8 carbonatoms; at least one thermally responsive 50 pH modifier, at least one base, and at least one binder mate FIG. 1 illustrates the initial reflectivity of thermochromic rial. The quantity of the thermally modified pH modifier is coating compositions coated on an optical article, prepared in less than or equal to about 0.25 milli moles based on the accordance with embodiments described herein. thermochromic optical-state change material. The thermo FIG. 2 illustrates the change in reflectivity of thermochro chromic ink composition is capable of transforming from a mic coating compositions coated on an optical article under 55 first optical state to a second optical state upon exposure to a varying storage conditions, prepared in accordance with thermal stimulus. embodiments described herein. Another embodiment of the invention is directed to a ther FIG. 3 illustrates the change in reflectivity of thermochro mochromic coating composition comprising at least one ther mic coating compositions coated on an optical article after mochromic optical-state change material, at least one ther being Subjected to a thermal activation, prepared in accor 60 mally responsive pH modifier, at least one base, and at least dance with embodiments described herein. one binder material. The quantity of the thermally responsive pH modifier is less than or equal to about 0.25 milli moles BRIEF DESCRIPTION based on the thermochromic optical-state change material. The thermochromic coating composition is capable of trans One embodiment of the invention is directed to a thermo 65 forming from a first optical State to a second optical state upon chromic ink composition comprising at least one thermochro exposure to a thermal stimulus. The thermochromic coating mic optical-state change material, at least one thermally composition is essentially free of solvent. US 8,002,851 B2 3 4 Another embodiment of the invention is directed to an may include an insubstantial number, or trace amounts, while article comprising a thermochromic ink composition depos still being considered free of the modified term. The singular ited in or deposited on the article. The thermochromic ink forms “a”, “an and “the include plural referents unless the composition comprises; at least one thermochromic optical context clearly dictates otherwise. state change material, at least one thermally responsive pH As used herein, the terms “disposed over” or “deposited modifier, at least one base and at least one binder material. over or “disposed between refer to both disposed directly in The quantity of the thermally modified pH modifier is less contact with and indirectly by having intervening layers ther than or equal to about 0.25 milli moles based on the optical ebetween. “Operably coupled' is a relationship between state change material. The thermochromic ink composition is listed parts that provides a stated function. capable of transforming from a first optical state to a second 10 One embodiment of the invention is directed to a thermo optical state upon exposure to a thermal stimulus. chromic ink composition comprising at least one thermochro These and other advantages and features will be more mic optical-state change material, at least one thermally readily understood from the following detailed description of responsive pH modifier, and at least one base and at least one preferred embodiments of the invention that is provided in binder material. The quantity of the thermally responsive pH connection with the accompanying drawing. 15 modifier is less than or equal to about 0.25 milli moles based on the thermochromic optical-state change material. The DETAILED DESCRIPTION thermochromic ink composition is capable of transforming from a first optical state to a second optical state upon expo One solution to this shoplifting problem, specifically for Sure to a thermal stimulus. optical media articles such as DVD’s, is to render at least a In one embodiment, the pH of the ink composition is due to portion of the content of the DVD inaccessible unless the a change in concentration of the thermally responsive pH retailer at the point-of-sale has activated the DVD. While modifier within the coating. In one embodiment, the change following this approach it should be taken into consideration in pH of the ink composition is due to a change in concentra that the time to activate the DVD at the POS should be tion of the thermally responsive pH modifier within the ink minimized while at the same time the shelflife of the inactive 25 composition due to evaporation, Sublimation, or degradation DVD should be maximized. One approach to rendering the of the thermally responsive pH modifier. In one embodiment, content of the DVD inaccessible prior to activation is to the change in concentration of the thermally responsive pH employ a thermochromic ink composition to deposit a ther modifier within the ink composition is irreversible. mochromic coating composition in or on the DVD, wherein The term “thermochromic' as used herein, describes mate the thermochromic coating composition at least partially 30 rials that undergo either a reversible or an irreversible ther absorbs the incident laser from an optical data reader so that mally induced color change. As used herein the term “optical the complete data directly in the optical path of the laser state change' material is used to describe a material which is cannot be read. In this instance, the optical article has no capable of existing in at least two different forms, each form value, and therefore there is no incentive for the shoplifter to possessing a unique optical state, for example a unique wave steal it. However, upon converting the DVD to an “activated 35 length associated with a maximum optical absorbance within state using an external stimulus at the point-of-sale, the ther a range from about 200 nm to about 800 nm, or a unique mochromic coating composition becomes Sufficiently trans extinction coefficient at a specific wavelength between about parent, with respect to the wavelength of the laser employed 200 nm to about 800 nm. in the optical data reader, due to a change in the optical One Suitable halochromic optical-state change material properties of the thermochromic coating composition, and 40 that may be used in the thermochromic ink composition is a the complete data directly in the optical path of the laser can chromic dye. As described herein the term “halochromic' now be read by the incident laser from the optical data reader, describes a material which changes optical state for example, therefore rendering the full content of the DVD accessible to color, upon a change in pH i.e., a change in the acidity or a legitimate consumer. basicity results in a change in the optical absorbance of the Various embodiments of thermochromic ink compositions, 45 chromic dye. This process is also known as 'acidic thermochromic coating compositions, articles comprising chromism' or “halochromism'. For example, the thermo thermochromic coating compositions, and Stability of the chromic ink composition may contain a thermochromic dye thermochromic coating compositions on the articles are i.e., a pH responsive dye such as for example a triaryl meth described below. Aspects of the embodiments described ylene dye. One example of a triaryl methylene dye is the herein can be used in combination with the materials, systems 50 Sodium salt of bromothymol blue, which undergoes a change and techniques previously disclosed in U.S. patent applica in its maximum optical absorbance from about 600 nm to tion Ser. Nos. 1 1/538,451, 11/567,271 and 11/831,180, to about 650 nm at a pH value greater than about 7 to an optical inhibit the theft or unauthorized use of optical articles. Thus absorbance below 450 nm at a pH values less than about 5. the disclosures of U.S. patent application Ser. No. 1 1/538, Within the scope of this disclosure the terms “pH or “change 451, filed Oct. 4, 2006, U.S. patent application Ser. No. 55 in pH are used to describe the acidity, basicity, or change in 11/567,271, filed Dec. 6, 2006, U.S. patent application Ser. acidity or basicity of the thermochromic ink composition. A No. 1 1/831,180, filed Jul. 31, 2007, are hereby incorporated decrease in the pH is a result of an increase in acidity (or by reference in their entireties. decrease in basicity) and an increase in the pH is a result of a Approximating language, as used herein throughout the decrease in acidity (or increase in basicity). In aqueous sys specification and claims, may be applied to modify any quan 60 tems, pH values less than 7 are classified as acidic and pH titative representation that could permissibly vary without values greater than 7 are classified as basic. resulting in a change in the basic function to which it is As used herein, the term "chromic dye describes optical related. Accordingly, a value modified by a term or terms, state change dyes which can exist in two different color forms such as “about is not limited to the precise value specified. In between about 200 nm to about 800 nm. In one embodiment, Some instances, the approximating language may correspond 65 the chromic dye is a triarylmethylene dye. Suitable non to the precision of an instrument for measuring the value. limiting examples of triarylmethylene dyes include bromo Similarly, “free” may be used in combination with a term, and cresol green, bromocresol purple, and corresponding salts US 8,002,851 B2 5 6 thereof. Non-limiting examples of thermochromic optical hexafluorophosphate, ethyl p-toluenesulfonate, dipenyliodo state change materials include but are not limited to bromo nium chloride, 4-octyloxyphenyl phenyl iodonium cresol green, bromocresol purple, bromophenol blue, thy fluoroantimonate, ammonium hexafluroantimonate, and molphthalein, thymol blue, aniline blue WS, durazol blue 4R, ethylbenzoate. durazol blue 8G, magenta II, mauveine, naphthalene blue In one embodiment, the thermochromic ink composition black, orcein, pontamine sky blue 5B, naphthol green B. further comprises a nitro dye having a Formula I, wherein R picric acid, martius yellow, naphthol yellow S. alcian yellow, comprises hydrogen or an alkyl group including 1 to 8 car fast yellow, metanil yellow, azo-eosin, Xylidine ponceau, bons. In one embodiment, R comprises hydrogen, methyl and orange G., ponceau 6R, chromotrope 2R, aZophloxine, lissa ethyl groups. Non limiting examples of nitro dyes include but mine fast yellow, tartrazine, amido black 10B, bismarck 10 are not limited to bis(2,4-dinitrophenyl)acetic acid ethyl brown Y, congo red, congo corinth, trypan blue, Evans blue, ester, (2,4-dinitrophenyl)acetic acid methyl ester, and (2,4- Sudan III, Sudan IV, oil red O, Sudan black B, Biebrich dinitrophenyl)acetic acid. In one embodiment, the nitro dye scarlet, Ponceau S, woodstain scarlet, Sirius red 4B, Sirius red comprises bis(2,4-dinitrophenyl)acetic acid ethyl ester. In F3B, fast red B, fast blue B. auramine O, malachite green, fast one embodiment, the amount of the nitro dye may be less than green FCF, lightgreen SFyellowish, pararosanilin, rosanilin, 15 or equal to about 1.0 milli moles based on the amount of the new fuchsin, Hoffman's violet, methyl violet 2B, crystal vio optical-state change material. In another embodiment, the let, Victoria blue 4R methyl green, ethyl green, ethyl violet, amount of the nitro dye may be in a range of about 0.1 milli acid fuchsin, water blue I, methyl blue, chrome violet CG, moles to about 0.75 milli moles based on the amount of the chromoxane cyanin R, Victoria blue R, Victoria blue B, night optical-state change material. In yet another embodiment, the blue, pyroninY. pyronin B, rhodamine B, fluorescein, eosinY amount of the nitro dye may be in a range of about 0.2 milli ws, ethyl eosin, eosin B. phloxine B, erythrosin B, rose ben moles to about 0.4 milli moles based on the amount of the gal, Gallein, acriflavine, acridine orange, primuline, thiofla optical-state change material. vine T, thioflavine S, safrainin O, neutral red, azocarmine G., The base may primarily be employed to increase the pH of aZocarmine B, Safrainin O. gallocyanin, gallamine blue, celes the ink and to ensure that the dye is in the basic form to start tine blue B, nile blue A, thionin, azure C, azure A, azure B, 25 with, i.e., the deeply colored form. In various embodiments, methylene blue, methylene green, toluidine blue O, alizarin, the amount of the base employed depends on the dye, the pH alizarin red S. purpurin, anthracene blue SWR, alizarin cya at which the color change occurs, etc. In certain embodi nin BBS, nuclear fast red, alizarin blue, Luxol fast blue MBS, ments, additional base may also help increase the color sta alcian blue 8GX, saffron, Brazilin and Brazilein, hematoxylin bility. Suitable non-limiting examples of bases include one or and hematein, laccaic acid, Kermes, carmine, and corre 30 more of ammonia, triethylamine, methyl amine, cyclohexy sponding salts thereof. In one embodiment, the optical-state lamine, dicyclohexylamine, 1.8-bis(dimethylamino)naph change material is sodium salt of bromothymol blue. thalene, 1,4-diazabicyclo[2.2.2]octane, dimethyl-4-meth In one embodiment, the amount of the optical-state change oxybenzylphenyl ammonium hexafluoroantimonate, material is in a range of from about 25 weight percent to about dimethyl-4-methylbenzyl, phenyl ammonium hexafluoroan 35 weight percent based on the weight of a coating formed 35 timonate; benzyldimethylphenyl ammonium hexafluoroanti using the composition. In another embodiment, the amount of monate, dimethyl-4-methoxybenzy14-methylphenyl ammo the optical-state change material is in a range of from about 28 nium triflate, dimethyl-4-methylbenzyl, phenyl ammonium weight percent to about 32 weight percent based on the triflate, benzyldimethylmethyl phenylammonium triflate, weight of a coating formed using the composition. In yet pyridine, imidazole, potassium hydroxide, and Sodium another embodiment, the amount of the optical-state change 40 hydroxide. In one embodiment, the base comprises dicyclo material is in a range of from about 29 weight percent to about hexyl amine or dimethyl-4-methoxybenzylphenyl ammo 31 weight percent based on the weight of a coating formed nium hexafluoroantimonate or a combination thereof. In one using the composition. embodiment, the amount of the base is in a range of from The quantity of the thermally responsive pH modifier about 0.5 milli moles to about 4.0 milli moles based on the appears to play an important role in the thermochromic ink 45 amount of optical-state change material. In another embodi composition and the thermochromic coating composition ment, the amount of the base is in a range of from about 1.0 prepared therefrom. In one embodiment, the quantity of the milli moles to about 3.0 milli moles based on the amount of thermally responsive pH modifier is in a range of from about optical-state change material. In yet another embodiment, the 0.01 milli moles to about 1 milli mole based on the amount of amount of the base is in a range of from about 2.0 milli moles optical-state change material. In another embodiment, the 50 to about 2.5 milli moles based on the amount of optical-state quantity of the thermally responsive pH modifier is in a range change material. of from about 0.05 milli moles to about 0.5 milli mole based In another embodiment, wherein the thermochromic ink on the amount of optical-state change material. In yet another composition is used to depositathermochromic coating com embodiment, the quantity of the thermally responsive pH position, the solubility of the different components of the modifier is in a range of from about 0.1 milli moles to about 55 thermochromic ink composition in the solvent should be such 0.35 milli mole based on the amount of optical-state change that there will be no phase separation of the different compo material. In one embodiment, the thermally responsive pH nents during the post-deposition drying step. In a further modifiers may be selected from one or more of sulfonic acid embodiment, wherein the thermochromic ink composition is salts, phosphoric acid salts, hydrochloric acid salts, triflic acid used to deposit a thermochromic coating composition on an salts, alkali metal salts, amine salts, ammonium salts, iodo 60 article suitable solvents include those that exhibit a chemical nium salts, and benzoic acid. Specific non-limiting examples inertness towards the material used to form the article. For of the thermally responsive pH modifiers include dinonyl example if the article is an optical article Such as for example naphthalene Sulfonate, dodecylbenzene Sulfonate, p-toluene a DVD made using a polycarbonate, the selected solvent(s) Sulfonate, (4-phenoxyphenyl)diphenylsulfonium trifluo should not induce solubilization, crystallization, or any other romethanesulfonate, bis(4-t-butylphenyl)iodonium 65 form of chemical or physical attack of the polycarbonate. p-toluenesulfonate, (4-t-butylphenyl)diphenlsulfonium tri This is essential to preserve the readability of the data under flate, triphenylsulfonium triflate, diphenyliodonium neath the thermochromic coating composition. In one US 8,002,851 B2 7 8 embodiment, in the case of solvent mixtures the volume frac poly(oxadiazoles), poly(benzothiazinophenothiazines), poly tion of any solvent that could potentially attack the polycar (benzothiazoles), poly(pyrazinoquinoxalines), poly(pyrom bonate may be less than about 30 percent. As used herein the ellitimides), poly(quinoxalines), poly(benzimidazoles), poly term “surface tension” refers to a property of the liquid that (OXindoles), poly(OXoisoindolines), poly(dioxoisoindolines), affects the spreading of a liquid on a Surface. The Surface poly(triazines), poly(pyridazines), poly(piperazines), poly tension will have a dramatic result on the final shape of a drop (pyridines), poly(piperidines), poly(triazoles), poly(pyra or multiple drops of liquid printed on solid surfaces. With Zoles), poly(pyrrolidines), poly(carboranes), poly(oXabicy respect to the ink formulations of the present disclosure, clononanes), poly(dibenzofurans), poly(phthalides), poly Surface tension is a critical parameter for printing the ink (acetals), poly(anhydrides), carbohydrates, blends of the formulations using conventional printing techniques such as, 10 above polymeric materials, and copolymers thereof. In one but not limited to, inkjet printing and Screen printing. Surface embodiment, the thermochromic ink composition comprises tension is also a parameter for the jetting process itself during a polymerizable monomer, such as an acrylate monomer inkjet printing, as it will affect how drops are formed at the (e.g., methyl methacrylate), which can be polymerized (i.e. print-head. If the Surface tension is not appropriate, inks will cured) to formathermochromic coating after the thermochro not be jettable with inkjet printing. 15 mic ink composition has been deposited on an optical article. Other aspects of suitable solvents include, but are not lim In one embodiment, the amount of the binder material is in a ited to, low vapor pressure and high boiling points so that the range from about 20 weight percent to about 60 weight per thermochromic ink is printable by methods known to one cent based on a weight of a coating formed using the compo skilled in the art, Such as for example, screen printing or sition. In another embodiment, the amount of the binder ink-jet printing methods. Solvents with lower boiling points material is in a range from about 30 weight percent to about may evaporate rapidly from the ink, causing clogging of 50 weight percent based on a weight of a coating formed inkjet print head nozzles or drying onto a printing screen, using the ink composition. In yet another embodiment, the either of which can lead to poor quality of the resultant ther amount of the binder material is in a range of about 35 weight mochromic coating. In one embodiment, a solvent with a percent to about 45 weight percent based on a weight of a boiling point above 130 degrees Celsius is employed. In 25 coating formed using the ink composition. various embodiments, the thermochromic ink composition As discussed above, the thermochromic ink composition is should be a physical mixture of the various components and capable of transforming from a first optical state to a second there should be no reactivity between the components at least optical state upon exposure to a thermal stimulus. The change under ambient conditions. from the first optical state to the second optical state occurs In one embodiment, suitable solvents employed in the ther 30 due to the presence of the thermochromic optical-state mochromic ink composition include, but are not limited to a change material. In one embodiment, the thermochromic glycol ether solvent, an aromatic hydrocarbon solvent con transformation from the first optical state to the second opti taining at least 7 carbon atoms, an aliphatic hydrocarbon cal state is a bistable transformation. As used herein, the term Solvent containing at least 6 carbon atoms, a halogenated “bistable transformation' is defined as a condition where the Solvent, an amine based solvent, an amide based solvent, an 35 optical state of the thermochromic ink composition corre oxygenated hydrocarbon Solvent, or miscible combinations sponds to one of two possible free energy minima and the ink thereof. Some specific Suitable non-limiting examples of such composition remains in its current optical state in the absence Solvents include diacetone alcohol (DAA), dipropylene gly of an external thermal stimulus that raises the compositions col methyl ether (Dowanol DPM), propylene glycol methyl temperature about 25 degrees Celsius. In one embodiment, ether (Dowanol PM), butyl carbitol, ethylene glycol, glycerol 40 the thermochromic ink composition is transformed from the with glycol ethers, cyclohexanone, and miscible combina first optical state to the second optical state in a temperature tions thereof. In one embodiment, the amount of the solventis range of from about 25 degrees Celsius to about 200 degrees in a range of from about 80 weight percent to about 90 weight Celsius. In another embodiment, the thermochromic ink.com percent based on the weight of the ink composition. In position is transformed from the first optical state to the another embodiment, the amount of the solvent is in a range 45 second optical State in a temperature range of from about 50 of from about 83 weight percent to about 87 weight percent degrees Celsius to about 190 degrees Celsius. In yet another based on the weight of the ink composition. In yet another embodiment, the thermochromic ink composition is trans embodiment, the amount of the solvent is in a range of from formed from the first optical state to the second optical state in about 84 weight percent to about 85 weight percent based on a temperature range of from about 100 degrees Celsius to the weight of the ink composition. 50 about 180 degrees Celsius. The primary function of the binder materials is to assist the The thermochromic ink composition may primarily find a adherence of a thermochromic ink composition to the Surface use in security applications. For example, if the thermochro of an article on which the thermochromic ink composition is mic ink composition is applied as a thermochromic coating deposited. Suitable non-limiting examples of binder materi composition on a DVD, and the DVD is to be legitimately als include one or more of a polymer, an oligomer, a poly 55 activated by a authorized store personnel at the POS, the time meric precursor, and a polymerizable monomer. Suitable taken for the activation should be conveniently short. If the non-limiting examples of polymeric materials include poly activation takes too much time one may find long queues at (alkenes), poly(anilines), poly(thiophenes), poly(pyrroles), the POS. In one embodiment, the time taken for a coating poly(acetylenes), poly(dienes), poly(acrylates), poly(meth comprising this composition in an optical article to bleach in acrylates), poly(vinyl ethers), poly(vinylthioethers), poly(vi 60 presence of a thermal source is less or equal to about 6 nyl alcohols), poly(vinyl ketones), poly(vinyl halides), poly seconds. In another embodiment, the time taken for a coating (vinyl nitriles), poly(vinyl esters), poly(styrenes), poly comprising this composition in an optical article to bleach in (arylenes), poly(oxides), poly(carbonates), poly(esters), poly presence of a thermal source is less or equal to about 4 (anhydrides), poly(urethanes), poly(Sulfonates), poly seconds. In yet another embodiment, the time taken for a (siloxanes), poly(sulfides), poly(thioesters), poly(Sulfones), 65 coating comprising this composition in an optical article to poly(sulfonamides), poly(amides), poly(ureas), poly(phosp bleach in presence of a thermal source is less or equal to about haZenes), poly(silanes), poly(silaZanes), poly(benzoxazoles), 2 seconds. In one embodiment, the optical reflectivity of the US 8,002,851 B2 10 coating after interaction with the thermal source is in a range least one binder material; wherein the quantity of the ther of about 40 percent to about 100 percent. In another embodi mally modified pH modifier is less than or equal to about 0.25 ment, the optical reflectivity of the coating after interaction milli moles based on the amount of optical-state change mate with the thermal source is in a range of about 65 percent to rial; and wherein the ink composition is capable of transform about 100 percent. In yet another embodiment, the optical ing from a first optical state to a second optical state upon reflectivity of the coating after interaction with the thermal exposure to a thermal stimulus. source is in a range of about 90 percent to about 100 percent. In still yet another embodiment, the invention is directed to In another embodiment, the time take for a film comprising a thermochromic ink composition comprising at least one this composition to bleach in the presence of a thermal source thermochromic optical-state change material consisting of of varying intensities is shown in Table 2 and discussed fur 10 sodium salt of bromothymol blue, at least one nitro dye hav ther, below. inga Formula I; wherein R comprises anhydrogen oran alkyl Further, as much as one would like the DVD's to be acti group including 1 to 8 carbons; at least one thermally respon vated in a minimum time period in the presence of a legitimate sive pH modifier, at least one base, and at least one binder thermal source, the thermochromic coating composition material; wherein the quantity of the thermally modified pH should provide a long shelf life to the inactive DVD, i.e., the 15 modifier is less than or equal to about 0.25 milli moles based composition should not degrade or decompose or self-acti on the amount of optical-state change material; and wherein vate under normal storage conditions, say for example, at a the ink composition is capable of transforming from a first temperature of about 25 to 50 degrees Celsius in the presence optical state to a second optical state upon exposure to a of air. In one embodiment, the time taken for a coating com thermal stimulus. prising this composition in an optical article to bleach under In still yet another embodiment, the invention is directed to storage at a temperature of about 25 degrees Celsius is about an article comprising a thermochromic ink composition 3 months to about 24 months. In another embodiment, the deposited in or deposited on the article, wherein the thermo time taken for a coating comprising this composition in an chromic ink composition comprises; at least one thermochro optical article to bleach under storage at a temperature of mic optical-state change material, at least one thermally about 25 degrees Celsius is about 6 months to about 12 25 responsive pH modifier, at least one base and at least one months. In yet another embodiment, the time taken for a binder material; wherein the quantity of the thermally respon coating comprising this composition in an optical article to sive pH modifier is less than or equal to about 0.25 milli moles bleach under storage at a temperature of about 25 degrees based on the optical-state change material; and wherein the Celsius is about 8 months to about 10 months. ink composition is capable of transforming from a first optical In one embodiment, the optical reflectivity of the coating 30 state to a second optical state upon exposure to a thermal after storage in the pre-activated State is less than or equal to stimulus. about 30 percent. In another embodiment, the optical reflec Another embodiment of the invention is directed to an tivity of the coating after storage pre-activated State is in a article comprising a thermochromic ink composition depos range of about 10 percent to about 25 percent. In yet another ited in or deposited on the article. The thermochromic ink embodiment, the optical reflectivity of the coating after stor 35 composition comprises; at least one thermochromic optical age pre-activated State is in a range of about 15 percent to state change material, at least one thermally responsive pH about 20 percent. modifier, at least one base and at least one binder material. In one embodiment, the thermochromic ink composition The quantity of the thermally modified pH modifier is less has a maximum optical absorbance in a range of about 200 nm than or equal to about 0.25 milli moles based on the optical to about 800 nm. In another embodiment, the thermochromic 40 state change material. The ink composition is capable of ink composition has a maximum optical absorbance in a transforming from a first optical state to a second optical State range of about 300 nm to about 700 nm. In yet another upon exposure to a thermal stimulus. embodiment, the thermochromic ink composition has a maxi In another embodiment, the invention is directed to a ther mum optical absorbance in a range of about 400 nm to about mochromic coating composition comprising at least one ther 650 nm. It will be appreciated that the specific wavelengths 45 mochromic optical-state change material, at least one ther for which the absorbance of the composition is maximized mally responsive pH modifier, and at least one base and at may be chosen to correspond to a particular application. For least one binder material. The quantity of the thermally instance, if the composition is intended for use with DVD responsive pH modifier is less than or equal to about 0.25 systems, the choice of wavelength should desirably corre milli moles based on the amount of optical-state change mate spond to the wavelengths in use in DVD players. 50 rial. The coating composition is capable of transforming from In another embodiment, the invention is directed to a ther a first optical state to a second optical state upon exposure to mochromic ink composition comprising at least one thermo a thermal stimulus. The coating composition is essentially chromic optical-state change material consisting of sodium free of solvent. salt of bromothymol blue, at least one thermally responsive As used herein, the term “coating describes a layered film pH modifier, and at least one base and at least one binder 55 structure. In certain embodiments, the layered film structure material. The quantity of the thermally responsive pH modi may comprise a single layer. In one embodiment, the thick fier is less than or equal to about 0.25 milli moles based on the ness of the coating is in a range from about 0.1 micron to amount of optical-state change material. The thermochromic about 100 microns. In another embodiment, the thickness of ink composition is capable of transforming from a first optical the coating is in a range from about 0.2 micron to about 10 state to a second optical state upon exposure to a thermal 60 microns. In yet another embodiment, the thickness of the stimulus. coating is in a range from about 0.25 micron to about 5 In yet another embodiment, the invention is directed to an microns. article comprising at least one thermochromic ink composi In one embodiment, the thermochromic coating composi tion consisting of an optical-state change material, at least one tion may be deposited on an article using the thermochromic nitro dye having a Formula I; wherein R comprises an hydro 65 ink composition by employing methods known to one skilled gen or an alkyl group including 1 to 8 carbons; at least one in the art. For example, screen printing and ink-jet printing thermally responsive pH modifier, at least one base, and at methods can be used. In one embodiment, the article is an US 8,002,851 B2 11 12 optical article. The thermochromic ink composition may be position and/or thermochromic coating composition. For converted to the corresponding thermochromic coating com example, an electrical device disposed in direct contact with position, using methods known to one skilled in the art. the marks on the optical article may provide the activation Exemplary methods include air drying at ambient conditions, signal when operably coupled with a POS equipment. drying under controlled temperature conditions such as for 5 As used herein, the term “remote' when used with respect example in an oven, drying under vacuum, and the like. In one to the application of the thermal stimulus to the thermochro embodiment, the thermochromic ink composition is essen mic ink composition and/or the thermochromic coating com tially free of solvent. As used herein, the term “essentially free position refers to an embodiment wherein the thermal stimuli of Solvent means that the thermochromic coating composi is not in “direct physical contact with the thermochromic ink tion may containless than about 0.1 weight percent of solvent 10 composition and/or thermochromic coating composition. based on the total weight of the thermochromic coating com One example wherein the thermal stimuli is applied remotely position. to a thermochromic coating composition is an embodiment In various embodiments, the thermochromic optical-state wherein at least a portion of the thermochromic coating com change material, the thermally responsive pH modifier, the position is coated with an optically transparent second layer, base, and the binder material, may be the same or similar to 15 which serves as a protective coating for the thermochromic those discussed above for the thermochromic ink composi coating composition from chemical and/or physical damage, tion. and wherein the application of the thermal stimuli to the In one embodiment, the thermochromic coating composi thermochromic coating composition is through the optically tion has a maximum optical absorbance in a range of about transparent second layer. Another example wherein the ther 200 nm to about 800 nm. In another embodiment, the ther mal stimuli is applied remotely to a thermochromic coating mochromic coating composition has a maximum optical composition is an embodiment wherein a ray of light is inci absorbance in a range of about 300 nm to about 700 nm. In yet dent on at least a portion of the thermochromic coating com another embodiment, the thermochromic coating composi position and the ray of light generates heat Sufficient to trans tion has a maximum optical absorbance in a range of about form the thermochromic coating composition from a first 400 nm to about 650 nm. As discussed above, it will be 25 optical state to a second optical state. appreciated that the specific wavelengths for which the absor In various embodiments of the invention, the optical article bance of the composition is maximized may be chosen to comprising the thermochromic coating composition may be correspond to a particular application. transformed from a “pre-activated state of functionality to an As used herein, the term “optical article' refers to an article “activated state of functionality. Conversion from the “pre that includes an optical data layer for storing data. The stored 30 activated state of functionality to the “activated state of data may be read by, for example, an incident laser of an functionality is achieved by the activation of the thermochro optical data reader device such as a standard compact disc mic coating composition, which is deposited in or on the (CD) or digital versatile disc (DVD) drive, commonly found optical article. Such that the thermochromic coating compo in most computers and home entertainment systems. In some sition is in optical communication with the optical data layer. embodiments, the optical article may include one or more 35 As used herein, the term optical communication refers to data layers. Furthermore, the optical data layer may be pro transmission and reception of light by optical devices. The tected by employing an outer coating, which is transparent to thermochromic coating composition is activated by interact the incident laser light, and therefore allows the incident laser ing with one or more thermal stimuli, applied either directly light to pass through the outer coating and reach the optical or remotely to the thermochromic coating composition. In data layer. Non-limiting examples of optical articles include a 40 one embodiment, the optical article may be activated using compact disc (CD); a digital versatile disc (DVD); multi thermal activation methods known to one skilled in the arts. layered structures, such as DVD-5 or DVD-9; multi-sided Non-limiting examples of the thermal activation methods structures, such as DVD-10 or DVD-18; a high definition include a wired activation method using a wired activation tag digital versatile disc (HD-DVD); a Blu-ray disc; a near field and a wireless activation method using a wirelessly-powered optical storage disc; a holographic storage medium; and a 45 flexible tag which are operatively coupled to the thermochro Volumetric optical storage medium, Such as, a multi-photon mic coating composition. The thermochromic coating com absorption storage format. In other embodiments, the optical position is one part of an anti-theft system designed to prevent article may also include an identification card, a passport, a the unauthorized use of the optical article, designed to workin payment card, a driver's license, a personal information card, combination with additional components of the anti-theft or any other documents or devices, which employ an optical 50 system Such as a removable wireless activation tag. Further data layer for data storage. details of the use of tags with optical articles as described In one embodiment, the thermochromic coating composi herein can be found in U.S. patent application Ser. No. tion is capable of irreversibly altering the state of functional 11/567,271, filed Dec. 6, 2006. ity of the optical article. In the “pre-activated state, at least In another embodiment, the optical article further com one portion of the data from the optical data layer is unread 55 prises a microheater, resistor, or resistive heating element in able by the incident laser of an optical data reader device, thermal contact with the thermochromic coating composi however, this same portion of data can be read from the tion. Further details of the use of microheater, resistor, or optical data layer in the “activated state of functionality. resistive heating element with optical articles as described The thermochromic ink composition and/or the thermo herein can be found in U.S. patent application Ser. No. chromic coating composition disclosed herein are capable of 60 11/567,271, filed Dec. 6, 2006. transforming from a first optical state to a second optical State Alternatively, the heating element may be in electrical upon exposure to either a director a remote thermal stimulus. communication with the electrical circuitry located in the As used herein, the term “direct' when used with respect to packaging of the optical article. In one embodiment, the elec the application of the thermal stimulus to the thermochromic trical circuitry may draw upon a source for electrical energy ink composition and/or the thermochromic coating composi 65 Such as a battery or charged capacitor in the packaging. At the tion refers to an embodiment wherein the thermal stimulus is POS the electrical circuitry in the packaging may then form in “direct' physical contact with the thermochromic ink com electrical connections with the activation source, thereby pro US 8,002,851 B2 13 14 viding the electrical energy for heating the thermochromic on the optical article. The “damaged state may be a result of coating. In certain embodiments, the packaging and/or tag improperactivation of one or more optical-state change mate comprises a battery configured to Supply electrical energy to rials in or on the optical article. In the “damaged' state at least the thermochromic coating, wherein the battery is stimulated a portion of the optical data layer cannot be read by the laser by the external stimulus. In these embodiments, the battery is of an optical data reader as a result of significant absorbance not directly stimulated by the external stimulus, but rather of the laser by at least a portion of at least one thermochromic provides power to heat the thermally responsive layer when optical-state change material. In contrast to the “activated the RF circuit is externally stimulated. state, where all the thermochromic coating composition is As used herein, the term “pre-activated state of function sufficiently transparent to the laser from the optical data ality refers to a state of functionality of the optical article 10 reader, in the “damaged state at least a portion of the ther where the thermochromic coating composition has not yet mochromic coating composition absorbs at least a portion of been exposed to one or more external stimuli, while the “acti the wavelength of the incident laser from the optical data vated state refers to a state of functionality where the ther reader and prevents the data directly in the optical path of the mochromic coating composition has been exposed to the laser from being read. external stimuli. In one embodiment, the “pre-activated' state 15 In various embodiments, the article comprises one or more comprises at least one thermochromic coating composition spots of the thermochromic coating composition wherein the which inhibits portions of the optical data layer that are spots have a first Surface and a second Surface. In embodi located directly in the optical path of the incident laser of an ments where two or more spots are employed, each of the optical data reader from being read. The activated State com spots may be located at a unique location on the article, prises a state of the optical article where the optical data layer designed to function in concert as part of the anti-theft sys can be read by the optical data reader as a result of the article tem. In one embodiment, at least two spots are in direct being exposed to at least one external stimulus. physical contact with each other, (i.e., juxtaposed next to each In another embodiment, at least one thermochromic coat other). Suitable examples of two spots in direct physical ing composition is at least partially transparent to the incident contact include, but are not limited to, concentric lines, con laser of an optical data reader in the pre-activated State, allow 25 centric arcs, concentric spots, patterned lines, patterned arcs, ing the data on the optical layer located directly in the optical patterned spots, lines or arcs which are positioned end-to-end, path of the laser to be read. In this embodiment, the thermo or any combination thereof. In one embodiment, the article chromic coating composition at least partially absorbs the comprises at least two spots, wherein at least one spot is not laser from the optical data reader in the activated state and transparent to the incident laser of an optical data reader in the prevents the data directly in the optical path of the laser from 30 “pre-activated state. If the article is converted from the “pre being read. activated state to the “damaged' state as a result of improper The change in the optical properties of the thermochromic activation, the optical properties of each of the spots are coating composition upon activation can occur using at least designed to change irreversibly such that at least a portion of two approaches. In the first approach, the thermochromic at least one of the spots absorbs the laser from the optical data coating composition at least partially absorbs the incident 35 reader, and prevents the data directly in the optical path of the laser from an optical data reader in the “pre-activated state, laser from being read. and the data directly in the optical path of the laser cannot be Upon interaction with one or more external stimuli, the read. In this instance, the content stored in the optical article optical absorbance of the thermochromic coating composi below the thermochromic coating is unplayable. Upon con tion may be altered to change the functionality of the optical Verting the optical article to the “activated State using an 40 article from the pre-activated state to the activated state. For external stimulus, the thermochromic coating composition is example, in the pre-activated State, the thermochromic coat at least partially transparent to the incident laser from an ing composition may render the optical article unreadable by optical data reader, the data directly in the optical path of the absorbing a portion of the wavelength from the incident laser laser can be read, and the content below the thermochromic of an optical data reader. However, upon interaction with an optical coating is playable. 45 external stimulus the thermochromic coating composition The second approach requires an additional 'authoring becomes transparent to the wavelength of the laser used to component, which allows the disc to be playable or unplay read the optical article, thereby making the portion of the able, depending on whether portions of the data on the optical optical data layer which is located directly in the optical path data layer can be read by the incident laser from an optical of the laser from the optical data reader readable in the acti data reader. An explanation of the term 'authoring as it 50 vated state. Suitable examples of external stimuli which can relates to an optical article, such as a DVD, can be found in generate a thermal stimulus may include a laser, infrared “DVD Authoring and Production”, by Ralph LaBarge, CMP radiation, thermal energy, X-rays, gamma rays, microwaves, Books, 2001. In this second approach, the thermochromic visible light, ultraviolet light, ultrasound waves, radio fre coating composition is at least partially transparent to the quency waves, microwaves, electrical energy, chemical incident laser from an optical data reader in the “pre-acti 55 energy, magnetic energy, or combinations thereof which gen vated state, and the data directly in the optical path of the erate a thermal stimulus. The interaction of the external laser can be read. In this instance, the optical article is stimulus with the optical article may include continuous, “authored unplayable. Upon converting the optical article to discontinuous, or pulsed forms of the external stimulus. the “activated State using an external stimulus, the incident Alternatively, instead of being deposited on the surface of laser from the optical data reader thermochromic coating 60 the optical article, the thermochromic coating composition composition is at least partially absorbed by thermochromic may be deposited inside the structure of the optical article. In coating composition, the data directly in the optical path of optical storage articles, the thermochromic coating composi the laser cannot be read, and the disc is “authored playable. tion may be deposited in the substrate on which the optical In one embodiment the term “damaged' state refers to a data layer is deposited. In Such an embodiment, the thermo state of functionality of the optical article where the optical 65 chromic coating composition may be mixed with the Sub article has undergone a physical modification Such as, but not strate material of the optical article. In alternate embodi limited to, a scratch, a dimple, or a physical modification in or ments, the thermochromic coating composition may be US 8,002,851 B2 15 16 deposited between the layers of the optical article, or may be Example 3 deposited within the layers of the optical article. For example, the thermochromic coating composition may be incorporated Provides a Thermochromic Ink Composition and a in the UV curable adhesive of the bonding (spacer) layer. It Method for Preparing the Same should be appreciated that these thermochromic coating com positions should be thermally stable to withstand the molding A 20 milliliters vial was charged with 0.226 grams of temperatures of the optical article. Also, these thermochromic sodium salt of Bromothymol blue, 1.971 grams of Dowanol (R) coating compositions may preferably absorb the wavelength DPM, 1.971 grams of diacetone alcohol, 0.3 grams of PMMA of the laser in one of the activated, or the pre-activated state of with a weight average molecular weight of about 15,000 as the optical article. Upon interaction with external stimulus, 10 measured using gel permeation chromatography using poly the thermochromic coating composition present inside the styrene standards, 0.143 grams of dicyclohexyl amine, and Substrate changes color. As a result, the Substrate may become 0.041 grams of CXC1612 (K3). The resultant mixture was transparent to the laser light, thereby facilitating the transmit stirred at about 25 degrees Celsius for about 4 hours to obtain a solution. until the polymer was completely dissolved. tance of laser light through the Substrate and making the 15 optical article readable. Example 4 In some embodiments, at least a portion of the thermochro mic coating composition is coated with an optically transpar Provides a Thermochromic Ink Composition and a ent second layer. The optically transparent second layer Method for Preparing the Same serves as a protective coating for the thermochromic coating composition from chemical and/or physical damage. The A 20 milliliters vial was charged with 0.226 grams of optically transparent second layer may contain cross-linkable sodium salt of Bromothymol blue, 0.05 grams bis(2,4-dini materials that can be cured using ultraviolet (UV) light or trophenyl)acetic acid ethyl ester, 1.971 grams of Dowanol.R. heat. Furthermore, the optically transparent second layer may DPM, 1.971 grams of diacetone alcohol, 0.3 grams of PMMA be a scratch resistant coating. For example, the optically 25 with a weight average molecular weight of about 15,000 as transparent second layer may include, but is not limited to, a measured using gel permeation chromatography using poly matrix consisting of cross-linkable acrylates, silicones, and styrene standards, 0.143 grams of dicyclohexyl amine, and nano or micron silicate particles. Suitable examples of an 0.041 grams of CXC1612 (K3). The resultant mixture was optically transparent second layer can be found in U.S. Pat. stirred at about 25 degrees Celsius for about 4 hours to obtain No. 5,990,188. 30 a solution in which the polymer was completely dissolved. EXAMPLES Example 5 Example 1 Provides a Thermochromic Ink Composition and a 35 Method for Preparing the Same Provides a Thermochromic Ink Composition and a A 20 milliliters vial was charged with 0.226 grams of Method for Preparing the Same sodium salt of Bromothymol blue, 0.05 grams bis(2,4-dini trophenyl)acetic acid ethyl ester, 2.426 grams of Dowanol.R. A 20 milliliters vial was charged with 0.218 grams of 40 PM, 1.673 grams of diacetone alcohol, 0.3 grams of PMMA bromothymol blue, 2.339 grams of dipropylene glycol with a weight average molecular weight of about 15,000 as methyl ether (Dowanol (R) DPM), 2.339 grams of diacetone measured using gel permeation chromatography using poly alcohol, 0.3 grams of polymethylmethacrylate (PMMA) with styrene standards, 0.143 grams of dicyclohexyl amine, and a weight average molecular weight of about 15,000 as mea 0.041 grams of CXC1612 (K3). The resultant mixture was Sured using gel permeation chromatography using polysty 45 stirred at about 25 degrees Celsius for about 4 hours to obtain rene standards, 0.159 grams of dicyclohexylamine, and 0.164 a solution in which the polymer was completely dissolved. grams of dimethyl-4-methoxybenzylphenyl ammonium hexafluoroantimonate, (i.e., CXC1612 (K3), obtained from Example 6 King Industries, Inc. (Norwalk, Conn.). The resultant mixture was stirred at about 25 degrees Celsius for about 4 hours to 50 Provides a Thermochromic Coating Prepared Using obtain a solution. until the polymer was completely dis the Thermochromic Ink Compositions of Example 1 solved. to 5 Example 2 The thermochromic coating was prepared by spin coating 55 a 50 micro liter sample of the ink onto a DVD disc at 3000 Provides a Thermochromic Ink Composition and a RPM for about 30 seconds to produce a deep blue coating Method for Preparing the Same having a thickness of about 0.5 microns. The coated DVD's were allowed to dry at room temperature (about 22 degrees A 20 milliliters vial was charged with 0.210 grams of Celsius) for about 12 hours in a dessicator with air purge. Bromocresol green, 1.983 grams of Dowanol RDPM, 1.983 60 These coated DVD's were used to measure kinetics of the grams of diacetone alcohol, 0.3 grams of PMMA with a coatings under various conditions. The results are included in weight average molecular weight of about 15,000 as mea Table 1, Table 2 and Table 3 below. Sured using gel permeation chromatography using polysty Table 1 provides the initial absorbance of the coating on the rene standards, 0.066 grams of dicyclohexylamine, and 0.137 DVD before being subjected to any storage or thermal stimu grams of CXC1612 (K3). The resultant mixture was stirred at 65 lus. Table 2 provides the absorbance of the coating on the about 25 degrees Celsius for about 4 hours to obtain a solu DVD at different time intervals at a fixed temperature of about tion. until the polymer was completely dissolved. 50 degrees Celsius. The data in Table 2 represents the effect of US 8,002,851 B2 17 18 storage on a coated DVD. Table 3 provides the absorbance of Play Station and X-Box, has demonstrated that the percent the coating on the DVD after being activated using a legiti reflectivity as measured by Ocean Optics spectrometer. In one mate thermal stimulus as may be used by the sales person at embodiment, the optical reflectivity of the film after storage a point-of-sale. The data in Table 3 provides the initial absor in the pre-activated State is less than or equal to about 25 bance, absorbance after activation at 120 degrees Celsius and percent. In another embodiment, the optical reflectivity of the the difference in the absorbance. The absorbance of the ther film after storage pre-activated State is in a range of about 10 mochromic coating was measured using a fiber optic UV-Vis to about 23. In yet another embodiment, the optical reflectiv spectrometer (Ocean Optics Inc.) in reflectance mode. The ity of the film after storage pre-activated State is in a range of measurements were made in triplicate and the average value about 15 to about 20. of the percent reflectivity plotted as illustrated in FIG. 1 (data 10 Referring to FIG. 1 a bar chart 100 indicating the initial from Table 1), FIG. 2 (data from Table 2), and FIG. 3 (data reflectivity of the thermochromic ink compositions prepared from Table 3). in Examples 1 to 5, when coated on an optical article is illustrated. The data represented in Table 1 is plotted as a bar TABLE 1. chart with the percent reflectivity plotted on the Y-axis 110 15 and the corresponding ink compositions indicated in the Example Percent X-axis 112. The first bar 114, the second bar 116, third bar Number Disc 1 Disc 2 Disc 3 Reflectivity 118, fourth bar 120, and the fifth bar 122 represent the percent 1 2S 23 22 17 15 16 24 25 22 21 reflectivity of the coating compositions prepared using the ink 2 18 20 21 23 23 17 16 16 18 19.1 compositions prepared in Examples 1, 2, 3, 4 and 5 respec 3 21 22 22 30 27 24 31 27 26 25.6 4 19 19 20 23 25 27 15 16 19 20.3 tively. The value of the reflectivity clearly indicates that the 5 18 17 17 16 16 1S 15 15 14 15.9 composition of Example 5 provides the lowest reflectivity of less than about 15 percent and hence provides the darkest spot. TABLE 2 Conditions Percent Reflectivity Example 50 degrees Celsius, in presence of air Number 0 days 3 days 6 days 10 days 26 days 1 17 15 16 34 28 27 34 29 28 41 36 35 42 38 38 2 22 23 17 34 30 27 3 34 31 41 38 34 49 47 42 3 30 27 24 42 36 35 40 38 34 49 45 45 50 47 50 4 23 25 27 40 40 40 38 36 36 47 45 45 49 50 49 5 16 16 15 15 1.6 16 14 15 14 16 16 16 17 16 16

TABLE 3 The second criterion is that the spot must remain stable to bleaching for long periods of time, or have a reasonably long Percent Reflectivity shelf or storage life. Referring to FIG. 2 a graph 200 indicat Example After activation at 120 Difference in 40 ing the change in reflectivity of thermochromic coating com Number Initial degrees Celsius reflectivity positions coated on an optical article under varying storage 1 30 90 60 conditions, prepared in Examples 1 to 5 is illustrated. The 2 35 S4 19 kinetics of the coatings on the DVD were studied at about 50 3 30 92 62 degrees Celsius for simulating accelerated shelflife. The data 4 2O 90 70 45 represented in Table 2 is plotted as a bar chart with the average 5 16 89 73 value of the percent reflectivity plotted on the Y-axis 210 and the corresponding ink compositions indicated in the X-axis As shown in Table 1, the percent reflectivity values range 212. The percent reflectivity was measured at 0 days, 3 days from about 15 to about 25. This indicates that the thermo and 6 days, 10 days, and 26 days at a temperature of about 50 chromic ink composition prepared in Examples 1-5 when 50 degrees Celsius. Table 4 below includes the reference numer coated on a DVD effectively block the laser and prevent the als for the corresponding bars in the bar chart. DVD from booting and playing prior to activation. The ther mochromic ink composition prepared in Example 5 provides TABLE 4 the least initial reflectivity. Further on activation at 120 degrees Celsius to mimic the activation at a POS, as shown in 55 Reference Day attemperature in Table 3, the percent reflectivity increases to about 54 to about Numeral Example degrees Celsius 90. This indicates that the coating on the DVD is transformed 214 1 Oat SO from dark (blocking the laser) to translucent (allowing at least 216 1 3 at SO a part of the laser to pass through) during a 2 second activation 218 1 6 at SO 220 1 10 at SO allowing for the customer to play the DVD. 60 222 1 26 at SO One skilled in the art will appreciate that there are at least 224 2 Oat SO three important criteria that must be met for a security tech 226 2 3 at SO 228 2 6 at SO nology to be successful. The first is that the ink spot must be 230 2 10 at SO dark enough so that all of the DVD players on the market will 232 2 26 at SO not boot or play when in the pre-activated state. Extensive 65 234 3 Oat SO testing with a large number of DVD players, including several 236 3 3 at SO popular game stations that double as DVD players such as US 8,002,851 B2 19 20 TABLE 4-continued a range of about 40 percent to about 100 percent. In another embodiment, the optical reflectivity of the film after interac Reference Day attemperature in tion with the thermal source is in a range of about 65 percent Numeral Example degrees Celsius to about 98 percent. In yet another embodiment, the optical 238 3 6 at SO reflectivity of the film after interaction with the thermal 240 3 10 at SO source is in a range of about 90 percent to about 95 percent. 242 3 26 at SO While the invention has been described in detail in connec 244 4 Oat SO 246 4 3 at SO tion with only a limited number of embodiments, it should be 248 4 6 at SO readily understood that the invention is not limited to such 250 4 10 at SO 10 disclosed embodiments. Rather, the invention can be modi 252 4 26 at SO 2S4 5 Oat SO fied to incorporate any number of variations, alterations, Sub 2S6 5 3 at SO stitutions or equivalent arrangements not heretofore 258 5 6 at SO described, but which are commensurate with the spirit and 260 5 10 at SO scope of the invention. Additionally, while various embodi 262 5 26 at SO 15 ments of the invention have been described, it is to be under stood that aspects of the invention may include some of the The values of the reflectivities clearly indicate that the com described embodiments. Accordingly, the invention is not to position of Example 5 retains the lowest reflectivity of less be seen as limited by the foregoing description, but is only than about 15 percent and hence provides the darkest spot limited by the scope of the appended claims. even after being Subjected to the accelerated Storage condi The invention claimed is: tions. 1. A thermochromic ink composition comprising: The third criteria is that the spot must activate or change at least one thermochromic optical-state change material, sufficiently from dark to translucent with heat that is sufficient at least one thermally responsive pH modifier, at least but not so intense that it damages the DVD disc. FIG. 3 one base, at least one binder material; and a solvent; illustrates the change in reflectivity of thermochromic ink 25 wherein the thermochromic optical-state change mate compositions when coated on an optical article after being rial comprises bis (2,4-dinitrophenyl)acetic acid ethyl subjected to thermal activation at about 120 degrees Celsius ester, wherein the solvent is propylene glycol methyl for about 2 seconds. A heater made from OhmegaPly(R) NiP ether, dipropylene glycol methyl ether, or mixture materials with a sheet resistivity of 50 ohms per square pat thereof; wherein the binder material comprises one or terned into a square of approximately 3 millimetersx3 milli 30 more of a polymer, an oligomer, a polymeric precursor, meters was used to heat a spot of the thermochromic coating or a polymerizable monomer; wherein the quantity of composition deposited onto the surface of a DVD. The figure the thermally responsive pH modifier is less than or shows the percent reflectivity of the ink compositions pre equal to about 0.25 milli moles based on the amount of pared in Examples 1 to 5, before and after thermal activation optical-state change material; and wherein the ink com as well as the delta reflectivity. Referring to FIG. 3 a graph 35 position is capable of transforming from a first optical 300 indicating the change in reflectivity of thermochromic state to a second optical state upon exposure to a thermal coating compositions coated on an optical article after being stimulus. Subjected to a thermal activation, prepared in Examples 1 to 5 2. The thermochromic ink composition as defined in claim is illustrated. The kinetics of the coatings on the DVD were 1, wherein the quantity of the thermally responsive pH modi studied at about 120 degrees Celsius for simulating activation 40 fier is in a range of from about 0.01 millimoles to about 1 milli at the POS. The data represented in Table 3 is plotted as a bar mole based on the amount of optical-state change material. chart with the average value of the percent reflectivity plotted 3. The thermochromic ink composition as defined in claim on the Y-axis 310 and the corresponding ink compositions 1, wherein the thermally responsive pH modifier is selected indicated in the X-axis 312. The percent before activation, from one or more of sulfonic acid salts, phosphoric acid salts, after activation, and the difference was measured. Table 5 45 hydrochloric acid salts, triflic acid salts, alkali metal salts, below includes the reference numerals for the corresponding amine salts, ammonium salts, iodonium salts, and benzoic bars in the bar chart. acid. 4. The thermochromic ink composition as defined in claim TABLE 5 1, wherein the amount of the nitro dye is less than or equal to 50 about 0.5 milli moles based on the amount of the thermochro Percent Day at mic optical-state change material. Reflectivity temperature 5. The thermochromic ink composition as defined in claim Reference Exam- beforefafter Reference in degrees 1, wherein the amount of the thermochromic optical-state Numeral ple difference Numeral Example Celsius change material is in a range of from about 25 weight percent 314 1 Before 330 3 Difference 55 to about 35 weight percent based on the weight of a coating 316 1 After 332 4 Before formed using the composition. 3.18 1 Difference 334 4 After 320 2 Before 336 4 Difference 6. The thermochromic ink composition as defined in claim 322 2 After 338 5 Before 1, wherein the base is selected from one or more of ammonia, 324 2 Difference 340 5 After triethylamine, methylamine, cyclohexylamine, dicyclohexy 326 3 Before 342 5 Difference 60 lamine, 1.8-bis(dimethylamino)naphthalene, 1,4-diazabicy 328 3 After clo2.2.2]octane, pyridine, imidazole, potassium hydroxide, and sodium hydroxide. Again, while all the ink formulations showed acceptable 7. The thermochromic ink composition as defined in claim results, the fifth formulation started out as the darkestand also 1, wherein the amount of the base is in a range of from about showed the largest delta. Player testing with a large number of 65 0.5 milli moles to about 4.0 milli mole equivalents based on different DVD players has showed that the reflectivity of a the amount of the thermochromic optical-state change mate thermally stimulated coating, in one embodiment, may be in rial. US 8,002,851 B2 21 22 8. The thermochromic ink composition as defined in claim 1, wherein the amount of the solvent is in a range of from about 80 weight percent to about 90 weight percent based on O OS the weight of the ink composition. NO R 9. The thermochromic ink composition as defined in claim 1, wherein the amount of the binder materialis in a range from about 20 weight percent to about 60 weight percent based on a weight of a coating formed using the composition. 10. The thermochromic ink composition as defined in ON ON NO2 claim 1, wherein the binder material comprises one or more of 10 a polyolefin, a polyester, a polyamide, a polyacrylate, a poly wherein R comprises hydrogen oran alkyl group having methacrylate, a polyvinylchloride, a polycarbonate, a 1 to 8 carbons, at least one thermally responsive pH polysulfone, a polysiloxane, a polyetherimide, a polyether modifier, at least one base, and at least one binder ketone, or a copolymer thereof. material; wherein the quantity of the thermally modi 11. The thermochromic ink composition as defined in 15 fied pH modifier is less than or equal to about 0.25 claim 1, wherein the thermochromic ink composition is trans milli moles based on the thermochromic optical-state formed from the first optical state to the second optical state in change material; and wherein the ink composition is a temperature range from about 25 degrees Celsius to about capable of transforming from a first optical state to a 200 degrees Celsius. second optical state upon exposure to athermal stimu 12. The thermochromic ink composition as defined in lus. claim 1, wherein the time taken for a coating comprising the 17. A thermochromic coating composition comprising: thermochromic ink composition in an optical article to bleach at least one thermochromic optical-state change material, in presence of a thermal source is less than or equal to about at least one thermally responsive pH modifier, at least 6 seconds. one base, and at least one binder material; and a solvent; 13. The thermochromic ink composition as defined in 25 wherein the thermochromic optical-state change mate claim 12, wherein the optical reflectivity of the coating after rial comprises bis (2,4-dinitrophenyl)acetic acid ethyl interaction with the thermal source is in a range of about 40 ester; wherein the solvent is propylene glycol methyl percent to about 100 percent. ether, dipropylene glycol methyl ether, or mixture 14. The thermochromic ink composition as defined in thereof; wherein the binder material comprises one or claim 1, wherein the time taken for a coating comprising the 30 more of a polymer, an oligomer, a polymeric precursor, thermochromic ink composition in an optical article to bleach or a polymerizable monomer; wherein the quantity of under storage at a temperature of about 25 degrees Celsius to the thermally modified pH modifier is less than or equal about 50 degrees Celsius is about 3 months to about 24 to about 0.25 milli moles based on the optical-state months. change material; wherein the coating composition is 15. The thermochromic ink composition as defined in 35 capable of transforming from a first optical state to a claim 14, wherein the optical reflectivity of the coating after second optical state upon exposure to a thermal stimu storage is less than or equal to 30 percent. lus; and wherein the coating composition is essentially 16. A thermochromic ink composition comprising: free of solvent. at least one thermochromic optical-state change material consisting of sodium salt of bromothymol blue, at least one nitro dye having a formula I