Claims:WE CLAIM:
1. A composition comprising an invisible component responsive to ultraviolet light having a nitrogen to carbon ratio in the range of 0.1 to 1.0, and an aqueous solution of at least one polymer having a pH greater than 4.
2. The composition as claimed in claim 1, wherein said aqueous solution of at least one polymer has a pH greater than 7, preferably greater than 7.5.
3. The composition as claimed in claim 1, wherein the ratio of said nitrogen to said carbon in said invisible component responsive to ultraviolet light is in the range of 0.4 to 0.6.
4. The composition as claimed in claim 1, wherein the particle size of said invisible component responsive to ultraviolet light is in the range of 1 nm to 200 nm.
5. The composition as claimed in claim 1, wherein the polymer solid content in said aqueous solution of at least one polymer is in the range of 5 wt% to 75 wt%, preferably 10 wt% to 60 wt%.
6. The composition as claimed in claim 1, wherein said invisible component responsive to ultraviolet light is characterized by being poorly absorptive in the wavelength range of 400 nm to 700 nm, highly absorptive in the wavelength range of 300 nm to 400 nm; and emits a wavelength in the range of 430 nm to 650 nm with ?max emission in the range of 450 nm to 600 nm, preferably in the range of 460 nm to 590 nm, upon irradiation by a light source in said highly absorptive range.
7. The composition as claimed in claim 1, wherein the ?max emission of said aqueous solution with an invisible component responsive to ultraviolet light having pH> 7 in the range of 450 nm to 500 nm shifts to 500 nm to 590 nm, when the pH of the aqueous solution of at least one polymer with an invisible component responsive to ultraviolet is reduced to be in the range of 4 to 7, or when it is diluted.
8. The composition as claimed in claim 1, wherein the ?max emission of said aqueous solution of at least one polymer with an invisible component responsive to ultraviolet light having pH> 7 in the range of 500 nm to 590 nm shifts to 450 nm to 500 nm, when the pH of the aqueous solution of at least one polymer with an invisible component responsive to ultraviolet is reduced to be in the range of 4 to 7, or when it is diluted.
9. The composition as claimed in claim 1, wherein the amount of said invisible component responsive to ultraviolet light is in the range of 0.0001 wt% to 0.1 wt% with respect to the weight of said aqueous solution of at least one polymer.
10. The composition as claimed in claim 1 further comprises at least one opacifying agent in an amount in the range of 2 wt% to 65 wt% with respect to the weight of said aqueous solution of at least one polymer.
11. The composition as claimed in claim 10, wherein said opacifying agent is selected from the group consisting of fillers, additives, pigments, extenders, crystallites of a semi-crystalline polymer, and dispersed phase of a micro- or nano-phase separated polymer.
12. The composition as claimed in claim 1, wherein said polymer has an anionic pendent group attached to the polymer backbone.
13. The composition as claimed in claim 1, wherein said polymer is a polymerization product of at least one or more monomers, wherein said monomer is selected from the group consisting of styrene, acrylic acid, methyl acrylic acid, malic anhydride, metylacrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate and at least one monomer having an anionic pendant
14. The composition as claimed in claim 13, wherein said at least one monomer having an anionic pendant is selected from acrylic acid, methyl acrylic acid, and malic anhydride and is present in a quantity sufficient to maintain the acid value of said polymer in the range of 1 of 100.
15. A process for producing a composition comprising an invisible component responsive to ultraviolet light comprising preparing an aqueous solution of at least one polymer having a pH greater than 4, and incorporating an invisible component responsive to ultraviolet light having a nitrogen to carbon ratio in the range of 0.1 to 1.0 to said polymer;
wherein said invisible component responsive to ultraviolet light is characterized by being poorly absorptive in the wavelength range of 400 nm to 700 nm, highly absorptive in the wavelength range of 300 nm to 400 nm; and emits a wavelength in the range of 430 nm to 650 nm with ?max emission in the range of 450 nm to 600 nm, preferably in the range of 460 nm to 590 nm, upon irradiation by a light source in said highly absorptive range.
16. The process as claimed in claim 15, wherein pH of said aqueous solution of at least one polymer is greater than 7, preferably greater than 7.5.
17. The process as claimed in claim 15, wherein an organic acid is added to the said aqueous solution of at least one polymer, to obtain said aqueous solution of at least one polymer having pH greater than 4.
18. The process as claimed in claim 17, wherein said organic acid is water soluble mono and polycarboxylic acid selected from the group consisting of citric acid, oxalic acid, succinic acid, tartaric acid, adipic acid, sebacic acid, maleic acid, fumaric acid, malic acid, malonic acid, formic acid, acetic acid, propionic acid, butyric acid, glycolic acid, and lactic acid.
19. The process as claimed in claim 15 comprises an additional step of incorporating at least one opacifying agent to said polymer prior to incorporating said invisible component responsive to ultraviolet lightinvisible component responsive to ultraviolet light.
20. The process as claimed in claim 19, wherein the amount of said opacifying agent is in the range of 2 wt% to 65 wt% with respect to the weight of said aqueous solution of at least one polymer.
21. The process as claimed in claim 15, wherein the particle size of said invisible component responsive to ultraviolet light is in the range of 1 nm to 200 nm.
22. The process as claimed in claim 15, wherein the amount of said invisible component responsive to ultraviolet light is in the range of 0.0001 wt% to 0.1 wt% with respect to the weight of said aqueous solution of at least one polymer.
23. The process as claimed in claim 15, wherein said invisible component responsive to ultraviolet light is present in at least one liquid medium.
24. The process as claimed in claim 23, wherein said liquid medium is at least one selected from the group consisting of water, linear aliphatic alcohols, branched aliphatic alcohols, glycols, and polyether glycols.
25. The claim as claimed in claim 24, wherein said linear aliphatic alcohols, branched aliphatic alcohols, glycols and polyether glycols have a maximum of 5 consecutive carbon atoms in between two heteroatoms.
26. The process as claimed in claim 15 further comprises at least one of a rheology additive, a dispersing agent, a wetting agent, a preservative, a defoamer, an anti-microbial additive, and a coalescing agent.
27. A composition comprising an invisible component responsive to ultraviolet light as claimed in any of the preceding claims, for use in a paint or ink formulation that is invisible under the illumination of visible light, and is visible under UV illumination.
28. A film obtained by applying said paint or ink formulation as claimed in claim 27 on a planar substrate, which has an incremental B value of minimum 10 units or more in the RGB index of color upon shining under incident ultraviolet light, as compared to that of a film of a paint or ink without said invisible component responsive to ultraviolet light applied on a planar substrate.

, Description:FIELD
The present disclosure relates to a composition comprising an invisible component responsive to ultraviolet light and a process for producing the same.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicates otherwise.
RGB index of color: The term “RGB index of color” refers to the creation of 8-bit image files with up to 256 colors. When converting to indexed color, the colors are stored and indexed in the image. If a color in the original image does not appear in the table, the program chooses the closest one or uses dithering to simulate the color using available colors.
B value: The term “B value” refers to the luminous intensity of blue color, i.e., its degree of lightness.
Invisible Ink: Invisible ink or invisible color is an ink or color, which is invisible either on application or soon thereafter, and can be later made visible by various means, such as application of heat or an appropriate chemical, or it may be made visible by viewing under ultraviolet (UV) light.
Opacifying agent: The term “Opacifying agent” refers to substances which are generally added to increase the opacity of the polymer dispersion or emulsion. These materials have a higher refractive index than that of polymer and/or have higher particle = 0.4 µm.
?max emission: The term “?max emission” refers to the wavelength at which absorbance is highest and hence is the wavelength to which the solution/substance is most sensitive to concentration changes.
Non-volatile matter: The term "non-volatile matter", hereinafter referred to as NVM, means material which does not volatilize when heated at 120 °C for sixty minutes. This material can be a liquid or a solid, or both.
Aqueous solution of at least one polymer: The term “aqueous solution of at least one polymer” refers to a solution, dispersion (transparent/opaque) or emulsion (milky/opaque) of a polymer.
Delta E (?E): The term “?E” refers to the color distance of the experimental sample from standard in visible colorspace. As the ?E increases the visible color difference between two samples also increases. If the ?E = 1.0 then the color difference is so minute that human eye is not able to detect the difference thus both sample appears to be identical in terms of color. ?E = 1.0 represent visible difference in color.
BACKGROUND
Invisible ink/color finds applications in various field, such as security marker pens, printing information without cluttering the already available information on a substrate, and the like.
One way of making invisible ink that is invisible under the illumination of visible light (400 nm to 700 nm) visible is to add a substance that can irradiate at another wavelength.
Conventionally, visible color is imparted to a polymer in the presence of opacifying substances. However, the presence of the opacifying substances in an otherwise clear (transparent) polymer hampers the visibility by diffusing the emission fluorescence and its detection to a certain extent due to diffraction of incident as well as emitted radiation, so that the B value in the RGB index of the emitted fluorescence color, as measured from a film of the polymer cast on a planar substrate, gets considerably depressed in comparison to that of a clear polymer in spite of incorporating the invisible color imparting substance. Further, incorporating high amount of the invisible color imparting substance to an opacified polymer may impart some visible color, as the color imparting substance has a minimum absorption in the visible wavelength region also, and that part of the absorbed light also starts emitting in the visible region thereby imparting a visible color.
Therefore, there is felt a need to provide a composition comprising an invisible component responsive to ultraviolet light that mitigates the drawbacks mentioned hereinabove.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Another object of the present disclosure is to provide a composition comprising an invisible component responsive to ultraviolet light.
Still another object of the present disclosure is to provide a process for the production of a composition comprising an invisible component responsive to ultraviolet light.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure provides a composition comprising an invisible component responsive to ultraviolet light and at least one polymer. The invisible component responsive to ultraviolet light has nitrogen to carbon ratio in the range of 0.1 to 1.0, preferably 0.4 to 0.6. The at least one polymer is present as an aqueous solution having a pH greater than 4. In an embodiment, the pH of the aqueous solution of at least one polymer is >7, preferably > 7.5. The invisible component responsive to ultraviolet light is characterized by being poorly absorptive in the wavelength range of 400 nm to 700 nm, highly absorptive in the wavelength range of 300 nm to 400 nm; and emits a wavelength in the range of 430 nm to 650 nm with ?max emission in the range of 450 nm to 600 nm, preferably in the range of 460 nm to 590 nm, upon irradiation by a light source in said highly absorptive range.
Typically, the ?max emission of the aqueous solution of at least one polymer emission of the aqueous solution with an invisible component responsive to ultraviolet light having pH> 7 in the range of 450 nm to 500 nm shifts to 500 nm to 590 nm, when the pH of the aqueous solution of at least one polymer with an invisible component responsive to ultraviolet is reduced to be in the range of 4 to 7, or when it is diluted. Further, the ?max emission of the aqueous solution of at least one polymer with an invisible component responsive to ultraviolet light having pH> 7 in the range of 500 nm to 590 nm shifts to 450 nm to 500 nm, when the pH of the aqueous solution of at least one polymer with an invisible component responsive to ultraviolet is reduced to be in the range of 4 to 7, or when it is diluted.
The composition of the present disclosure can be produced by preparing an aqueous solution of at least one polymer having a pH greater than 4, and incorporating an invisible component responsive to ultraviolet light having nitrogen to carbon ratio in the range of 0.1 to 1.0 to the polymer.
The composition of the present disclosure can be used in a paint or ink formulation that is invisible under the illumination of visible light, and is visible under UV illumination. The film obtained by applying the paint or ink formulation of the present disclosure on a planar substrate, has an incremental B value of minimum 10 units or more in the RGB index of color upon shining under incident ultraviolet light, as compared to that of a film of a paint or ink without the invisible component responsive to ultraviolet light applied on a planar substrate.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figures 1a-1d illustrate the graphical representation of the effect of the amount of the invisible component responsive to ultraviolet light on the B value of the polymer composition; and
Figure 2 illustrates the graphical representation of the effect of the amount of the opacifying agent responsive to ultraviolet light on the B value of the polymer composition.
DETAILED DESCRIPTION
The present disclosure envisages a composition comprising an invisible component responsive to ultraviolet light having an optimum amount of the invisible color imparting substance, so that a differentiated and detectable incremental B value is obtained without imparting visible color to the composition and at least one polymer.
In an aspect of the present disclosure, there is provided a composition comprising an invisible component responsive to ultraviolet light and at least one polymer. Particularly, the composition comprises an invisible component responsive to ultraviolet light having nitrogen to carbon ratio in the range of 0.1 to 1.0 and an aqueous solution of at least one polymer having a pH greater than 4.
In an embodiment, the aqueous solution of at least one polymer has a pH greater than 7. In an exemplary embodiment, the aqueous solution of at least one polymer has a pH greater than 7.5.
Typically, the invisible component responsive to ultraviolet light is characterized by being poorly absorptive in the wavelength range of 400 nm to 700 nm, highly absorptive in the wavelength range of 300 nm to 400 nm; and emits a wavelength in the range of 430 nm to 650 nm with ?max emission in the range of 450 nm to 600 nm, preferably in the range of 460 nm to 590 nm, upon irradiation by a light source in this highly absorptive range.
The ?max emission of the aqueous solution of at least one polymer emission of the aqueous solution with an invisible component responsive to ultraviolet light having pH> 7 in the range of 450 nm to 500 nm shifts to 500 nm to 590 nm, when the pH of the aqueous solution of at least one polymer with an invisible component responsive to ultraviolet is reduced to be in the range of 4 to 7, or when it is diluted. This means that when the original ?max emission of the aqueous solution of at least one polymer (pH>7) with the invisible component responsive to ultraviolet light is low (450 nm to 500 nm), there is “red shift”, i.e., a shift towards the higher wavelength when the pH aqueous solution of at least one polymer with invisible component responsive to ultraviolet light is maintained in the range of 4 to 7, or when it is diluted.
On the other hand, the ?max emission of the aqueous solution of at least one polymer with an invisible component responsive to ultraviolet light having pH> 7 in the range of 500 nm to 590 nm shifts to 450 nm to 500 nm, when the pH of the aqueous solution of at least one polymer with an invisible component responsive to ultraviolet is reduced to be in the range of 4 to 7, or when it is diluted. This means that when the original ?max emission of the aqueous solution of at least one polymer (pH>7) invisible component responsive to ultraviolet light is high (500 nm to 590 nm), there is “blue shift”, i.e., a shift towards the lower wavelength when the pH aqueous solution of at least one polymer with invisible component responsive to ultraviolet light is maintained in the range of 4 to 7, or when it is diluted.
In an embodiment, the ratio of nitrogen to carbon in the invisible component responsive to ultraviolet light is in the range of 0.4 to 0.6.
Typically, the particle size of the invisible component responsive to ultraviolet light is in the range of 1 nm to 200 nm.
The polymer solid content in the aqueous solution of at least one polymer is in the range of 5 wt% to 75 wt%, preferably 10 wt% to 60 wt%.
The amount of the invisible component responsive to ultraviolet light invisible component responsive to ultraviolet light can be in the range of 0.0001 wt% to 0.1 wt% with respect to the weight of the aqueous solution of at least one polymer.
Typically, the polymer has an anionic pendent group attached to the polymer backbone. The polymer can be an acrylic or styrene acrylic polymer synthesized by polymerizing or co-polymerizing common acrylic, vinylic monomers with or without common acrylic monomers. The monomers can be selected from the group comprising styrene, vinylidene chloride, vinylidene fluoride, vinyl acetate, vinyl acetate derivatives (VeoVa), acrylic acid, methyl acrylic acid, malic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, propyl acrylate, n-butyl methyl acrylate, t-butyl methyl acrylate, and 2-hydroxy ethyl acrylate. One or more monomers can be taken together and polymerized. At least one of the monomers selected from the group consisting of acrylic acid, methacrylic acid, malic anhydride is present in an amount such that the acid value of the resultant polymer is in the range of 1-100 acid value. These polymers can be made basic by adding bases, such as ammonium hydroxide, or water soluble organic amines (ethyl amine, diethyl amine, triethyl amine, morpholine, amino alcohols, aromatic amines, and the like), the final pH of these polymers is typically =7. The polymer can be in the form of a solution, a dispersion, or an emulsion, which may be transparent, translucent, milky, or hazy.
In an embodiment of the present disclosure, the composition further comprises at least one opacifying agent. The opacifying agent can be selected from the group consisting of fillers, additives, pigments, extenders, crystallites of a semi-crystalline polymer, and dispersed phase of a micro- or nano-phase separated polymer. The polymer can be same as the polymer used in the aqueous solution of a polymer or a different polymer. The amount of the opacifying agent can be in the range of 2 wt% to 65 wt% with respect to the weight of the aqueous solution of at least one polymer. In an embodiment, the opacifying agent is a mixture of a pigment and an extender. The pigment can be at least one selected from the group consisting of rutile titanium dioxide, anatase titanium dioxide, zinc oxide, leaded zinc oxide, zinc sulfide, lead titanate, antimony oxide, zirconium oxide, white lead, basic lead silicate, lithopone, titanated lithopone, titanium-barium pigment, titanium-calcium pigment and titanium-magnesium pigment. The extender can be at least one selected from the group consisting of calcium carbonate, clays, dolomite, marble powder, and metal silicates. In an embodiment, the ratio of the pigment to the extender is 3:1.
In another aspect of the present disclosure, there is provided a process for producing a composition comprising an invisible component responsive to ultraviolet light. The process comprises preparing an aqueous solution of at least one polymer having a pH greater than 4, and incorporating an invisible component responsive to ultraviolet light having nitrogen to carbon ratio in the range of 0.1 to 1.0 to the polymer. The invisible component responsive to ultraviolet light is typically characterized by being poorly absorptive in the wavelength range of 400 nm to 700 nm, highly absorptive in the wavelength range of 300 nm to 400 nm; and emits a wavelength in the range of 430 nm to 650 nm with ?max emission in the range of 450 nm to 600 nm, preferably in the range of 460 nm to 590 nm, upon irradiation by a light source in the highly absorptive range. The composition of present disclosure is invisible under illumination by visible light, and is visible under UV illumination.
In an embodiment, the aqueous solution of at least one polymer has a pH greater than 7. In an exemplary embodiment, the aqueous solution of at least one polymer has a pH greater than 7.5.
In another embodiment, an organic acid is added to the aqueous solution of at least one polymer, to obtain an aqueous solution of at least one polymer having pH greater than 4. The organic acid is a water soluble mono and polycarboxylic acid selected from the group consisting of citric acid, oxalic acid, succinic acid, tartaric acid, adipic acid, sebacic acid, maleic acid, fumaric acid, malic acid, malonic acid, formic acid, acetic acid, propionic acid, butyric acid, glycolic acid, and lactic acid.
The particle size of the invisible component responsive to ultraviolet can be in the range of 1 nm to 200 nm.
The amount of the invisible component responsive to ultraviolet can be in the range of 0.001 wt% to 0.1 wt% with respect to weight of the aqueous solution of at least one polymer.
Typically, the invisible component responsive to ultraviolet light material is present in a liquid medium. The liquid medium is at least one selected from the group consisting of water, linear aliphatic alcohols, branched aliphatic alcohols, glycols, and polyether glycols. The linear aliphatic alcohols, branched aliphatic alcohols, glycols and polyether glycols have a maximum of 5 consecutive carbon atoms in between two heteroatoms.
In an embodiment, the process comprises an additional step of incorporating at least one opacifying agent to the aqueous solution of at least one polymer prior to incorporating the invisible component responsive to ultraviolet light. The opacifying agent can be selected from the group consisting of fillers, additives, pigments, extenders, crystallites of a semi-crystalline polymer, and dispersed phase of a micro- or nano-phase separated polymer. The polymer can be same as the polymer used in the aqueous solution of a polymer or a different polymer. The amount of the opacifying agent can be in the range of 2 wt% to 65 wt% with respect to the weight of the aqueous solution of at least one polymer.
At least one of a rheology additive, a dispersing agent, a wetting agent, a preservative, a defoamer, an anti-microbial additive, and a coalescing agent may be used to prepare the composition of the present disclosure.
In one embodiment, water is mixed with an opacifying agent, rheology additive, a dispersing agent, a wetting agent, a preservative, a defoamer, and an anti-microbial additive, and milled or ground to obtain a resultant mixture which is typically filterable through 200 mesh. The polymer, a coalescing agent, a defoamer and water is then added. The invisible component responsive to ultraviolet light can be added during any of the process step.
The invisible component responsive to ultraviolet light used in the composition of the present disclosure may be prepared by treating a carbon source with a nitrogen source in an aqueous medium at a temperature in the range of 150 °C to 210 °C, and at a pressure in the range of 8 bar to 18 bar. In an embodiment, the aqueous medium is deionized water. The carbon source can be selected from the group consisting of citric acid, ascorbic acid, adipic acid, succinic acid, sebacic acid, oxalic acid, tartaric acid, glucose, carbohydrates, glycols. The nitrogen source can be selected from the group consisting of ethylenediamine urea, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and 2-amino-2-methyl-1-propanol, polyethylene diamine, diethyl amine, ammonium hydroxide, and ammonium chloride.
The composition comprising an invisible component responsive to ultraviolet light can be used in a paint or ink formulation that is invisible under the illumination of visible light, and is visible under UV illumination. The film obtained by applying the paint or ink formulation on a planar substrate has an incremental B value of minimum 10 units or more in the RGB index of color upon shining under incident ultraviolet light, as compared to that of a film of a paint or ink without the invisible component responsive to ultraviolet light applied on a planar substrate.
In an exemplary embodiment, the viscosity pick-up for the composition of the present disclosure with respect to the initial viscosity in Kerbs Unit when subjected to 55 °C for 30 days is = 10%. The composition is capable of retaining the fluorescence without alteration when subjected to 55 °C for 30 days. The B-value increase = 10 units with 0.001% dosage on solids at system opacifying agent dosage at 62%. No particle agglomeration is observed in the composition with or without the opacifying agent. When the invisible component responsive to ultraviolet light is added in clear polymer without opacifying agent, transparency loss of the film =0.5%, in 400-700 nm range is observed. The color impact, i.e., delta E (?E) of the invisible component responsive to ultraviolet light in the composition is = 0.5.
The present disclosure is further described in light of the following laboratory scale experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. These laboratory scale experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial/commercial scale.
Experimental details
Experiment-1: Preparation of the compositions comprising an invisible component responsive to ultraviolet light in accordance with the present disclosure (with opacifying agent)
The composition was prepared by mixing an opacifying agent with aqueous solution of a polymer having alkaline pH (7.5) and acidic pH (4), which were transparent and capable of forming a film. The opacifying agent and the polymer used are summarized in Table-1A and Table-1B. The ratio of both the opacifying agent and the polymer was kept constant for each experiment and different dosages of the invisible component responsive to ultraviolet light dispersion were added to the mixture. The effect of the invisible component responsive to ultraviolet light on blue light emission under UV 365 nm was observed using a Colorimeter having a mobile camera.
Table-1A: Different compositions for the composition comprising an invisible component responsive to ultraviolet light (pH of aqueous solution of the polymer =7.5)
Constituent (%) Composition IA Composition IIA Composition IIIA
Opacifying agent
(titanium dioxide + calcium carbonate in the ratio of 3:1) 35 52 62
Polymer
(styrene acrylate copolymers) 65 48 38

Table-1B: Compositions comprising an invisible component responsive to ultraviolet light (pH of aqueous solution of polymer =4)
Constituent (%) Composition IB Composition IIB Composition IIIB
Opacifying agent
(titanium dioxide + clay in the ratio of 3:1) 35 52 62
Polymer
(styrene acrylate/vinyl acetate and vinyl acetate derivative copolymer), pH=4 65 48 38

The Colorimeter captures the images of the composition and provides the RGB values of the captured images. As the invisible component responsive to ultraviolet light of the present disclosure absorbs in the UV region and fluoresces in the blue region, the intensity can be measured by B value in the RGB scale. Only the B value as a representative of the blue emission intensity and thus relating to the quantity of invisible component responsive to ultraviolet light in composition was studied. It was found that as the quantity of the invisible component responsive to ultraviolet light increases, the B value also increases.
Invisible component responsive to ultraviolet light was added to each opacified alkaline polymer in different amounts ranging from 0.001 wt% to 1.000 wt%. It is observed that the relationship of increasing B value with dosage is not linear, but a logarithmic one, which is in accordance with the Beer-Lambert law. In the presence of a lower amount of invisible component responsive to ultraviolet light in the range of 0.00 wt% to 0.005 wt%, negligible increase in B value was observed, the detectability started when the amount of invisible component responsive to ultraviolet light was 0.01 wt% in the Composition IA, as illustrated in Figure-1a and Figure-1b. The relationship between increasing the invisible component responsive to ultraviolet light amount and the B value for Composition IIA and Composition IIIA is illustrated in Figure-1c, and Figure-1d respectively. It is seen from Figure-1c, and Figure-1d that for Composition IIA and Composition IIIA, increasing the amount of invisible component responsive to ultraviolet light, results in an increase in the B value. Figure-2 illustrates the comparative study of the relationship between the opacifying agent and the B value. In Figure-2, Line-A represents Composition IA, Line-B represents Composition IIA, and Line-C represents Composition IIIA. It is seen from Figure-2 that for all the compositions, at a constant amount of invisible component responsive to ultraviolet light, the B value decreases with increasing amount of the opacifying agent. Therefore, an inverse relationship exists between the amount of the opacifying agent and the B value.
Experiment-2: Preparation of the compositions comprising an invisible component responsive to ultraviolet light in accordance with the present disclosure (without opacifying agent)
The compositions were prepared by mixing invisible component responsive to ultraviolet light in different dosage with an aqueous solution of polymer having alkaline pH (7.5), which was transparent and capable of forming a film and the compositions are summarized in Table-2. The effect of the invisible component responsive to ultraviolet light on green light emission under UV 365 nm was observed using a Colorimeter having a mobile camera.
Table-2: Compositions comprising an invisible component responsive to ultraviolet light without opacifying agent (pH of aqueous solution of polymer =7.5)
Constituent (%) Composition IC Composition IIC Composition IIIC
Invisible component responsive to ultraviolet light 0.001 0.005 0.010
Polymer (styrene acrylate copolymers) pH=7.5 99.999 99.995 99.990

Experiment-3: Effect of dilution/acidification on the composition of the present disclosure
The composition was prepared by mixing invisible component responsive to ultraviolet light with an aqueous solution of polymer having alkaline pH (7.5) which was transparent and capable of forming a film. The composition is summarized in Table-3a.
Table-3a: Composition comprising an invisible component responsive to ultraviolet light in accordance with the present disclosure (pH=7.5)
Constituent (%) Composition ID
Invisible component responsive to ultraviolet light 0.01
Polymer (styrene acrylate/Vinyl acetate and Vinyl acetate derivative copolymers) pH=7.5 99.999
The composition (Composition ID) exhibited a blue light emission under UV at 365 nm.
The composition (Composition ID) of Table-3a was acidified by adding an organic acid, to obtain Composition IE having the composition as summarized in Table-3b.
Table-3b: Composition comprising an invisible component responsive to ultraviolet light in accordance with the present disclosure (pH=5)
Constituent (%) Composition IE
Composition ID (pH=7.5) 95
Organic acid to bring pH to 5 5

A shift in the emission from blue light to green under UV at 365 nm was observed in case of Composition IE.
Next, a composition (Composition IF) was prepared by mixing invisible component responsive to ultraviolet light with an aqueous solution of polymer having alkaline pH (7.5) which was transparent and capable of forming a film. The composition is summarized in Table-4a.
Table-4a: Composition comprising an invisible component responsive to ultraviolet light in accordance with the present disclosure (pH=7.5)
Constituent (%) Composition IF
Invisible component responsive to ultraviolet light 0.1
Polymer (styrene acrylate/Vinyl acetate and Vinyl acetate derivative copolymers) pH=7.5 99.5

The composition (Composition IF) exhibited a green light emission under UV at 365 nm.
The composition (Composition IF) of Table-4a was diluted by adding water, to obtain Composition IG having the composition as summarized in Table-4b.
Table-4b: Composition comprising an invisible component responsive to ultraviolet light in accordance with the present disclosure
Constituent (%) Composition IG
Composition IF (pH=7.5) 2
water 98
A shift in the emission from green light to blue light under UV at 365 nm was observed in case of Composition IE.
It is seen from Experiment-3 that even though there is a shift in the ?max emission when the aqueous solution of polymer having pH > 7 is acidified (pH=4 to 7) or is diluted, the ?max emission remains within the range of 450 nm to 600 nm.
TECHNICAL ADVANCES
The present disclosure described herein above has several technical advantages including, but not limited to, a composition comprising an invisible component responsive to ultraviolet light that is invisible under illumination by visible light, and is visible under UV illumination. The amount of the invisible component responsive to ultraviolet light results in slight increase in the B value, without imparting a visible color to the polymer.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.