A light diffusing ink for coating on a substrate and a coated automotive glazing thereof

Abstract

Disclosed in the present invention is a light diffusing ink (103) for coating on a substrate (101), wherein said ink (103). It comprises a film forming resins and a pre-treated enamel dispersed in said film. Said ink (103) is adapted to exhibit light diffusion property with illuminance of 30-200 lux, in the presence of a guided light (102) and to exhibit a transparency of more than 85%, in the absence of the guided light (102). The ink is adapted to withstand high temperature and pressure. It is a cost-effect solution for lighting applications in glazing, signboards and the like. The formulated ink is compatible for coating on any polymeric film substrate.

Description

[0001] A LIGHT DIFFUSING INK FOR COATING ON A SUBSTRATE AND A COATED AUTOMOTIVE GLAZING THEREOF

[0002] TECHNICAL FIELD

[0003] The present disclosure broadly relates to a light diffusing ink for coating on a substrate. It particularly relates to a transparent light diffusing ink, specifically suitable for automotive glazing.

[0004] BACKGROUND

[0005] Background description includes information that may be useful in understanding the present disclosure. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed disclosure, or that any publication specifically or implicitly referenced is prior art.

[0006] Light diffusing ink (LDI) is known to be used for screen printing on optically transparent substrate such as glass or for plastic surface printing. Coating using such LDI is visible only through a dedicated illumination using LED (for example). In coating using such LDI, the printed image is not visible in natural or artificial light condition or without any lighting, while it will be visible, only when a source like a LED source, located at the edges of the transparent substrate, is switched on. Such ink finds wide range of industrial applications in at least signage, habitat, and automotive industries. LDI uses the phenomenon of light diffusion which is the scattering of light rays at multiple angles other than at just one angle as is the case with specular reflection. For certain applications, such as and not limited to usage of the ink for edge lighting in automotive glazing, it is crucial for the ink to remain stable retaining its properties even at high temperature and pressure. Reference is made to W02013162106A1 that discloses a LDI which has at least one ink binder selected from the group consisting of an acrylic resin, a vinyl chloride copolymer (PVC Copolymer), a Cellulose Acetate Butylate (CAB) resin, a Cellulose Acetate (CA) resin, and a Nitro Cellulose (NC) resin. The light diffusing agent may be chosen from a group consisting of silicon beads, silica, barium sulfate, calcium carbonate and titanium dioxide. However, the temperature stability, and light diffusion luminosity of the ink is not apparent from this disclosure. The illuminance obtained by means of the diffusing agents is also not provided in this disclosure.

[0007] Another reference is made to US20220289990A1 that discloses a screen-printing light diffusing ink for printing on an optically transparent substrate and being integrable with devices used to light said substrate from an edge with a light incident angle less than 42°. Said ink comprising an organic matrix and having a light diffusion inorganic oxide agent dispersed in the matrix. Again, the stability of the ink at high temperature and pressure is not apparent from this disclosure. Similarly, the transparency or illuminance is also not apparent from this disclosure.

[0008] It has thus been observed that the printable ink known in the prior art solution includes one or several drawbacks. It does not meet a desired transparency for application in glazing solutions, it is not known to be stable at elevated temperature and pressure. Furthermore, it is desirable for such an ink to be suitable for all means of applications and to provide uniform illuminance.

[0009] In regard of the prior art known hitherto, there exists a need of a transparent ink for application on a substrate such that it is optically transparent in the absence of a guided light and is visible in the presence of said guided light. It is desirable for said ink to have improved transparency, illuminance (in presence of guided light), and ability to remain stable in presence of elevated temperatures (more than 160°C), elevated pressures (up to 13 bar). SUMMARY OF THE DISCLOSURE

[0010] An object of the present invention is to provide a solution for overcoming the drawbacks of the prior art.

[0011] Another object of the present invention is to provide an ink with high transparency in the absence of guided light and high illuminance in the presence of guided light.

[0012] Yet another object of the present invention is to provide ink that can maintain its mechanical and light diffusive properties even at high temperature and pressure.

[0013] A further object of the present invention is to provide a cost-effective light diffusing ink with uniform illuminance.

[0014] These and other objects of the invention are achieved by the following aspects of the invention. The following disclosure presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This presents some concept of the invention in a simplified form to a more detailed description of the invention presented later. It is a comprehensive summary of the disclosure, and it is not an extensive overview of the present invention. The intent of this summary is to provide a fundamental understanding of some of the aspects of the present invention.

[0015] In an aspect of the present invention is disclosed a light diffusing ink for coating on a substrate. The ink comprises a film forming resins and a pre-treated enamel dispersed in said film. The ink is adapted to exhibit light diffusion property with illuminance of 30-200 lux, in the presence of a guided light. At the same time, the ink is adapted to exhibit a transparency of more than 85%, in the absence of the guided light. The film forming resins comprises a polymer selected from a group consisting of nitrocellulose polymer or poly methyl methacrylate (PMMA) or Polydimethylsiloxane (PDMS). The pre-treated enamel includes a mixture of enamel concentration dissolved in a solvent, preferably present in a ratio of approximately 1 : 5 by weight percentage. This solvent is preferably diacetone alcohol or xylene. The pre-treated enamel concentration is a colloid containing mono-dispersed enamel particles of smaller sizes. This colloid is dispersed in the film forming resins in a ratio ranging in 3:7 to 0.2:9.8 by volume. The substrate on which the ink could be coated may be an optically transparent substrate preferably made of glass or polymer selected from a group containing polyesters, polyamides, polyimides, polycarbonates, polyethylene, polyethylene products, polypropylene, acrylate-containing products, PMMA, their copolymers or any combination thereof. The ink has a refractive index of the ranging from 1.45 to 1.55 and the pre-treated enamel has a refractive index of at least 2. The ink is adapted to exhibit a transmittance of at least 85% in the wavelength range of visible light in the absence light from said guided light source.

[0016] In another aspect of the present invention is provided a composite pane for automotive glazing. It comprises a first substrate of glass or polymer having a first face and a second face, a second substrate of glass or polymer having a third face and a fourth face, and one or more interlayers sandwiched between said first substrate and second substrate forming a single unit. The pane further comprises a coating of a light diffusing ink between said first substrate and second substrate and a lighting means to selectively provide guided light on said coating. The lighting means is disposed along the peripheral region of the composite pane. This ink, disclosed in the earlier aspect, is adapted to selectively diffuse light emitting from said lighting means. The coating is provided on the second face of the first substrate or the third face of the second substrate. It has a thickness of 10-100 pm and is adapted to exhibit stability at a temperature of up to 166°C and a pressure of up to 13 bar. The lighting means is adapted to emit light to be incident through the peripheral region of the composite pane. It may alternatively be adapted to provide light rays on the coating via a through-hole provided on the composite pane. Further, the composite pane may comprise a prism layer on one surface of the pane and said lighting means is then disposed on a surface opposite to the prism layer. The prism layer is configured to guide light on the coating for diffusion.

[0017] In yet another aspect of the present invention is disclosed a process of making of the composite pane which has been detailed in the previous embodiment. Said method comprises pre-processing the first substate and the second substrate, bending the first substrate and the second substrate, coating the ink on the second face of the first substrate or on the third face of the second substrate, assembling the interlayer between the first substrate and the second substrate, de-airing the assembled first substrate, second substrate and the interlayer therebetween and autoclaving the de-aired assembly of the first substrate, second substrate and the interlayer therebetween. It further includes suitably arranging the lighting means around the peripheral region of the composite pane for illuminating the coating.

[0018] The one or more aspects of the present invention provides ink for coating with a desired transparency and illuminance and the application of the same for instance in edge lighting. It is capable of withstanding high temperatures and pressure without losing its properties. It is a cost-effective solution, and is capable of being used in varied applications.

[0019] The significant features of the present invention and the advantages of the same will be apparent to a person skilled in the art from the detailed description that follows in conjunction with the annexed drawings.

[0020] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0021] The following briefly describes the accompanying drawings, illustrating the technical solution of the embodiments of the present invention or the prior art, for assisting the understanding of a person skilled in the art to comprehend the invention. It would be apparent that the accompanying drawings in the following description merely show some embodiments of the present invention, and persons skilled in the art can derive other drawings from the accompanying drawings without deviating from the scope of the disclosure.

[0022] FIGs. 1A-1B illustrate a substrate coated with the transparent ink respectively according to an embodiment of the present invention.

[0023] FIGs. 2A-2B illustrate a composite pane having coating of the transparent ink with different means of lighting according to an embodiment of the present invention.

[0024] FIG. 3 illustrate a method of manufacturing a composite pane with the transparent ink coating according to an embodiment of the present invention.

[0025] FIG. 4 illustrate comparison of the transparency of the ink according to an embodiment of the present invention and the bare substrate.

[0026] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the disclosure.

[0027] DETAILED DESCRIPTION OF THE DISCLOSED INVENTION

[0028] The present disclosure is now discussed in more detail referring to the drawings that accompany the present application. It would be appreciated by a skilled person that this description is to assist in the understanding of the invention, but these are to be regarded as merely exemplary. The terms and words used in the following description are not limited to the bibliographical meanings and the same are used to enable a clear and consistent understanding of the invention. Accordingly, the terms / phrases are to be read in the context of the disclosure and not in isolation. Additionally, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0029] The embodiments of the present invention relate to a composition of a transparent light diffusing ink for coating on a substrate such as glass or any polymer. This ink comprises of a mixture of a solvent with microscopically dispersed insoluble particles of another substance suspended throughout. Said another substance is an engineered colloid of an enamel diluted with an alcohol-based solvent. This ink may be applied in glazing as a light diffusing coating for all static display applications.

[0030] Reference is made to FIG. 1A that provides a coated substrate (100) having the transparent ink coating (103) according to an embodiment of the invention. In the absence of light from a source (102) specifically meant to be incident on the coating (103), the coating is observed to be substantially transparent and is barely visible on the substrate (101). But once light from the source (102) is provided directed on the coating (103), the ink diffuses the light to illuminate the coating such as depicted in FIG. IB. In this embodiment, is provided a light diffusing ink for coating on a substrate (101). Said ink comprises a film forming resins and a pre-treated enamel dispersed in said solution. In a preferred embodiment, said ink is adapted to exhibit a light diffusion illuminance of 30-200 lux, in the presence of a guided light source (102). In the preferred embodiment, the film forming resins comprises a polymer selected from a group comprising of nitrocellulose polymer or poly methyl methacrylate (PMMA) or Polydimethylsiloxane (PDMS). The ink contains pre-treated enamel. The pre-treated enamel concentration is a colloid containing mono-dispersed enamel particles of smaller sizes. The term mono-dispersed is used to indicate particles that belong to a similar size range. Said substrate (101) for coating may be an optically transparent substrate preferably made of glass or polymer selected from a group containing polyesters, polyamides, polyimides, polycarbonates, polyethylene, polyethylene products, polypropylene, acrylate-containing products, PMMA, their copolymers or any combination thereof.

[0031] In an embodiment of the present invention is disclosed the ink comprising an enamel for light diffusion. Said enamel is pre-treated by dissolving in a solvent, preferably in an organic solvent such as diacetone alcohol or xylene. In a preferred embodiment, the solution is prepared with concentration (weight percentage) of the enamel and solvent in the ratio of around 1:5. Particle size plays a vital role in providing the desired haze which in turn affects the transparency. The enamel dissolved in the organic solvent is further treated to obtain a colloid containing mono-dispersed enamel particles of smaller sizes. In an implementation, the particle size of the enamel is reduced by centrifugation (other possible means exists as well), followed by filtration of the particles with lower particle size or manual sedimentation by allowing the enamel solution to settle down to separate the bigger particles from the smaller particles. It has been observed that smaller the size of the particle, better would be the transparency of the ink with improved light diffusion. All the enamel particles in the film forming resins have similar sizes or sizes in a similar range and hence are referred as being monodispersed. This consequently results in uniform diffusion of light and formation of bright image display with sharp edges of the coating with said ink.

[0032] A ‘film forming resins’ referred herein, may be defined as a semi-liquid substance which is configured to hold host particles. It is desirable for said film forming resin to have a binding agent. It would be known to one skilled in the art that resin is a solid or highly viscous substance of organic or inorganic origin that is typically convertible into polymers. Resins are used as adhesives, coatings or as a construction material itself. It has wide applications, which is owed to its strong bond forming nature. In a preferred embodiment of the present invention, a bio-polymer such as nitrocellulose may be chosen as film forming resins and it is prepared by dissolving it in either ethyl acetate or butyl acetate.

[0033] In an embodiment is disclosed that the clear colloid with the smaller particles is obtained by pre-treated enamel which is collected and dispersed in the prepared solution of the resin forming solution. An instance of such a resin forming solution is a preparation of a solution of nitrocellulose, in a volume ratio ranging in 3:7 to 0.2: 9.8 (both limits inclusive) respectively. It would be appreciated by one skilled in the art that this instance has been provided by means of an example and not by means of limitation. Similar such resin forming solutions may be used as well without departing from the scope of this disclosure. The ink thus obtained is adapted to have a refractive index which matches with the refractive index of the substrate which is getting coated. In a preferred embodiment, the refractive index of ink ranges from 1.45 to 1.55, while the pre-treated enamel has a refractive index of 2 or higher to diffuse light. The refractive index of glass is 1.5. For the coating of the ink on glass to appear transparent in the absence of any guided light, it is desirable for the refractive indices of glass and the coated ink to match or align. If the refractive indices of the ink and the substrate do not match, the desired transparency of the coating in the absence guided light would not be obtained. A suitable solvent, compatible with the film forming resin, may be added to adjust the viscosity of the composition of the ink. The ink is compatible for coating on any substrate such as and not limited to glass. The formulation of the ink has a transmittance of more than 85% in the visible wavelength region, in the absence of guided incident light meant for dispersion. The ink coating has been found to have a value of illumination ranging from 40 to 200 lux for visible light. In an implementation, the illuminance and transmittance of the ink may be varied by tuning the ratio of its constituents. The ink is adapted to withstand high temperatures (more than 160° C) and high pressures (of up to 13 bar) without losing its properties. The ink is formulated to be made compatible with the transparent substrate and each precursor ratio is tuned to achieve maximum illuminance and transmittance. Said ink is formulated to be abrasion resistant. This is particularly, desirable for being applications of edge lighting in sidelites.

[0034] This ink can be cured at normal atmospheric conditions, without any need for dedicated curing apparatus such as a furnace or UV curing means. However, this does not limit the curing capabilities of the ink as it may also be cured at elevated temperatures and / or using any dedicated apparatus. The ink is adapted to be cured the same manner when coated on any polymeric film comprising at least one of the group of polyesters, polyamides, polyimides, polycarbonates, polyethylene, polyethylene products, polypropylene, acrylate-containing products, PMMA, their copolymers or any combination thereof, or any other transparent or printable substrate. In other words, the coating of the ink and its curing is not limited by the substrate. The formulated ink may be coated or applied on the substrate via conventional coating means such as and not limited to screen printing, doctor blade-pull technique and spray coating and any other physical coating techniques. The ink is formulated for being coated on both flat and bent substrates. Further, the formulated ink is non-toxic in nature and hence may be used for a varied range of applications such as and not limited to edge lighting on glass for aesthetics. The components of the ink do not interact and produce hazardous results. The formulated ink finds application for display or lighting related uses cases in glazing such as and not limited to facades, double glazing, triple glazing, windshield, sidelite, backlite, quaterlite, sunroof.

[0035] In an embodiment of the present invention is disclosed a composite pane (110) for automotive glazing in a vehicle as depicted in FIG. 2A. Said composite pane or alternatively often referred as laminated glass comprises a first substrate (111) of glass or polymer having a first face (fl), a second face (f2), a second substrate (112) of glass or polymer having a third face (IB) and a fourth face (f4) and one or more interlayers (113) sandwiched between said first substrate and second substrate forming a single unit composite pane. The first face (fl) is defined as the face facing the exterior of the vehicle and similarly, the fourth face (f4) is defined as the face facing the interior of the vehicle. The second face (f2) and third face (f3) are disposed to face the interlayer. The composite pane (100) further comprises a coating (114a, 114b, 114c) of the light diffusing ink between said first substrate (111) and second substrate (112), in which said coating is of the transparent ink defined in an earlier embodiment of the present invention. The coating may be applied as a single layer coat or may be coated as a logo or any writing or one or more patterns or designs, however not limited to these examples. Further provided in the composite pane is a lighting means (120) to selectively provide guided light on said coating, wherein said lighting means (120) is disposed along the peripheral region of the composite pane (110). In a preferred embodiment, the coating may be provided on the second face (f2) of the first substrate or the third face (13) of the second substrate. In an implementation, the ink may be used for coating glass substrates for making a laminated glazing such as a windshield. Said ink is formulated to be coated on bent glasses and to withstand the autoclaving conditions as well. The coating on the glazing is adapted to exhibit stability of temperature and pressure of up to a temperature of 166°C and a pressure of 13 bar respectively (however, not limited to this). Accordingly, the coating on the composite pane sustains the conditions of autoclaving conditions. In a preferred embodiment, the ink has a thickness of 10- 100 pm.

[0036] The lighting means (120) is so arranged that it provides light on the coating. In an implementation, the lighting means (120) may be arranged in a manner such that the light rays are incident through the edge or the peripheral region of the composite pane (110). This lighting arrangement is schematically depicted in FIG. 2A. In an alternate implementation, the lighting means (120) may be provided by means of a through-hole drilled on the composite pane such that light is guided on the coating. In a further implementation, the composite pane (100) may be provided with a prismatic layer or film (115) on one surface and the lighting means (120) on another surface. The prismatic layer (115) and the lighting means (120) are so arranged that said layer (115) is configured to provide collimated light (for glass light incident at 40° or 45°, the angle of incidence is equal or greater than critical angle of the substrate) on the coating. The lighting means may be any conventional source of light such as and not limited to LED. Light from the source such as LED when incident on the coated substrate, gets infused from the edges of the pane, to undergo total internal reflection. The substrate herein functions as a waveguide. When incident on the coating, the light spreads uniformly throughout the coating and yields a display of the coating.

[0037] In an embodiment of the present invention is provided a process of making of the composite pane, in which the substrate of the pane is preferably glass. Said process comprises pre-processing (S201), the first substate and the second substrate of glasses. Such pre-processing activities would involve cutting, grinding or both. The method further includes bending (S202), both the first substrate and the second substrate. This is followed by coating (S203), the ink on the second face of the first substrate or on the third face of the second substrate or both the said faces. The use cases would govern on which face coating need to be applied. The coating may be done using conventional means. This is further followed by the assembly (S204) of the interlayer between the first substrate and the second substrate. The assembled first substrate, second substrate and the interlayer therebetween is then de-airing (S205). Subsequent is the step of autoclaving (S206), the de-aired assembly of the first substrate, second substrate and the interlayer therebetween. In an implementation, the autoclaving occurs at high temperatures such as above 160°C and high pressure 13 bar. This process may be employed in the making of laminated glass for windshield. Eurther to this the method comprises arranging (SI 07), the lighting means around the peripheral region of the composite pane for illuminating the coating. The arrangement of the lighting means may include adding source of light to provide guided light on the coating. Adding the source of light may be such that the light rays are incident through the edge or the peripheral region of the composite pane, or by means of adding a lighting means via a through-hole or by means of adding collimated light by additional prism layer.

[0038] In a preferred embodiment, said composite pane may be used for an automotive glazing such as windshield. The transparency of the ink is such that in the absence of a guided light source the coating is not visible. The presence of mono-dispersed particles facilitate for uniform diffusion of light and bright image may be displayed with sharp edges. Since, it can withstand elevated temperatures without losing its properties, it finds a number of use cases in laminated glass application such as and not limited to edge lighting in windshield. In an implementation, the film forming resins is dissolved in a volatile solvent for easy coating and quick curing.

[0039] Industrial Application: The application of this ink may be primarily focused on static display applications for glazing such as for an edge light infusion in automotive glazing. When light is infused from the edges of the glazing, it undergoes total internal reflection through the glazing and the glass acts as a waveguide. Upon contact with the coating, the light spreads uniformly throughout the coating and yields a bright image / text with crisp and sharp edges, in which said image or text is coated using the ink. The coating may be so applied that it forms shapes or even logos or even writings. The lighting source for such applications may include LED, however, not limited to it. It may be used for light effects on acrylic sheets, billboards, signboards, other decoration boards and transparent displays. It may further be used for edge lighting in glazing in buildings as well for improving the aesthetics.

[0040] Example 1: For formulation of the ink, the enamel may be pre-treated before being dispersed in a film forming resin or matrix. Said matrix for binding the enamel particles may be prepared by dissolving nitrocellulose in a solvent such as ethyl acetate or butyl acetate to obtain a homogeneous polymer mixture. The enamel is prepared by dissolving in diacetone alcohol or xylene. Further to which, the particle size of the enamel is reduced for being dispersed in said homogeneous polymer mixture of nitrocellulose.

[0041] Example 2: Reference is made to FIG. 4 that discloses the comparison of the transparency of the bare glass and the glass along with the coating of the ink according to the present invention. As evidenced from the figure, the ink exhibits transparency such that when coated on a substrate, it is barely visible in the absence of guided light. Further, in the following is provided the tabulated data obtained by the formulation of the ink in different ratios of the combination of film forming resin (comprising the binder) and the pre-treated enamel. It has been seen that with different ratios, different illuminance and transmittance are obtained:

[0042] Table 1 : Ratio of constituents, illuminance, and transmittance

[0043] Depending on the application a suitable combination of the film forming resin and the enamel may be chosen. The precursor ratio may be tuned to achieve maximum illuminance and transmittance.

[0044] Example 3: The tuned transparent ink according to the present invention has been formulated to be abrasion resistant. Such application may be used for coating on the sidelite of a vehicle. As would be evidenced from Table 2, the ink has been tuned to be abrasion resistant. Further, in the following is provided the tabulated data obtained for demonstrating abrasion resistance:

[0045] Table 2: Data demonstrating Abrasion Resistant

[0046] Some advantages of the present invention are enlisted in the following:

[0047] • The coating with the ink disclosed in the present invention provides near invisible coating in the absence of a guided light source. There is barely any haze.

[0048] • In the presence of a guided light source, it provides high illuminance.

[0049] • It is a cost-effect solution for lighting applications in glazing, signboards and the like.

[0050] • The formulated ink is compatible for coating on any polymeric film substrate.

[0051] Features that are described and / or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and / or in combination with or instead of the features of the other embodiments.

[0052] It would be appreciated by the skilled person that present invention includes various combinations of mechanical elements and features. It is understood that the invention may be practiced with various combinations of elements or features, and that such combinations are within the scope of the invention as defined by the claims. Although embodiments have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the system and method described herein. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

[0053] Many alterations and modifications of the present invention will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. It is to be understood that the description above contains many specifications, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the personally preferred embodiments of this invention. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents rather than by the examples given.

[0054] List of reference numerals appearing in the accompanying drawings and the corresponding features:

[0055] 100: coating substrate with light source

[0056] 101: substrate

[0057] 102, 120: light source

[0058] 103: ink

[0059] 110: coated composite pane

[0060] 111: first substrate

[0061] 112: interlayer

[0062] 113: second substrate

[0063] 114a, 114b, 114c: ink coating fl : first face f2: second face

[0064] 13 : third face f4: fourth face 115: prism layer

[0065] S201-S207: steps of the method of making of composite pane

Claims

Claims1. A light diffusing ink (103) for coating on a substrate (101), wherein said ink (103) comprises: a film forming resins; and a pre-treated enamel dispersed in said film; wherein said ink (103) is adapted to exhibit light diffusion property with illuminance of 30-200 lux, in the presence of a guided light on the ink (102).

2. The light diffusing ink (103) as claimed in claim 1, wherein the ink is adapted to exhibit a transparency of more than 85%, in the absence of the guided light (102).

3. The light diffusing ink (103) as claimed in claim 1 or claim 2, wherein said film forming resins comprises a polymer selected from a group consisting of nitrocellulose polymer or poly methyl methacrylate (PMMA) or Polydimethylsiloxane (PDMS).

4. The light diffusing ink (103) as claimed in any one of claims 1-3, wherein the pre-treated enamel includes a mixture of enamel concentration dissolved in a solvent, preferably present in an approximate ratio of 1 : 5 by weight percentage.

5. The light diffusing ink (103) as claimed in any one of claims 1-4, wherein said solvent is diacetone alcohol or xylene.

6. The light diffusing ink (103) as claimed in in any one of claims 1-5, wherein the pre-treated enamel concentration is a colloid containing mono-dispersed enamel particles.

7. The light diffusing ink (103) as claimed in in any one of claims 1-6, wherein said colloid is dispersed in the film forming resins in a ratio ranging in 3:7 to 0.2: 9.8 by volume.

8. The light diffusing ink (103) as claimed in any one of claims 1-7, said substrate (101) is an optically transparent substrate preferably made of glass or polymer selected from a group containing polyesters, polyamides, polyimides, polycarbonates, polyethylene, polyethylene products, polypropylene, acrylate-containing products, PMMA, their copolymers or any combination thereof.

9. The light diffusing ink (103) as claimed in any one of claims 1-8, has a refractive index of the ranging from 1.45 to 1.55.

10. The light diffusing ink (103) as claimed in any one of claims 1-9, wherein the pre-treated enamel has a refractive index of at least 2.

11. A composite pane (110) for automotive glazing comprising: a first substrate (111) of glass or polymer having a first face (fl) and a second face (f2); a second substrate (113) of glass or polymer having a third face (f3) and a fourth face (f4); one or more interlayers (112) sandwiched between said first substrate (111) and second substrate (113) forming a single unit; a coating (114a, 114b, 114c) of a light diffusing ink between said first substrate (111) and second substrate (113); and a lighting means (120) to selectively provide guided light on said coating (114a, 114b, 114c), wherein said lighting means (120) is disposed along the peripheral region of the composite pane (110); and wherein said light diffusing ink as claimed in any one of the claims 1 to 10 is adapted to selectively diffuse light emitting from said lighting means (120).

12. The composite pane (110) as claimed in claim 11, wherein the coating (114a, 114b, 114c) is provided on the second face (f2) of the first substrate (111) or the third face (13) of the second substrate (113).

13. The composite pane (110) as claimed in claim 11 or claim 12, wherein the ink is adapted to have a thickness of 10-100 pm.

14. The composite pane (110) as claimed in any one of claims 11-13, wherein said ink is adapted to exhibit stability at a temperature of up to 166°C and a pressure of up to 13 bar.

15. The composite pane (110) as claimed in any one of claims 11-14, wherein the lighting means (120) is adapted to emit light to be incident through the peripheral region of the composite pane (110).

16. The composite pane (110) as claimed in any one of claims 11-15, wherein the lighting means (120) is adapted to provide light rays on the coating (114a, 114b, 114c) via a through -hole provided on the composite pane (110).

17. The composite pane (110) as claimed in any one of claims 11-16, further comprises a prism layer (115) on one surface of the pane (110) and said lighting means (120) is disposed on a surface opposite to the prism layer (115).

18. The composite pane (110) as claimed in any one of claims 11-17, wherein the prism layer (115) is configured to guide light on the coating (114a, 114b, 114c) for diffusion.

19. A method of making the composite pane as claimed in any of the claims 11 to 18, wherein said method comprises:pre-processing (S201), the first substate and the second substrate; bending (S202), the first substrate and the second substrate; coating (S203), the ink on the second face of the first substrate or on the third face of the second substrate; assembling (S204), the interlayer between the first substrate and the second substrate; de-airing (S205), the assembled first substrate, second substrate and the interlayer therebetween; autoclaving (S206), the de-aired assembly of the first substrate, second substrate and the interlayer therebetween; and arranging (SI 07), the lighting means around the peripheral region of the composite pane for illuminating the coating.

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