DESC:FIELD
The present disclosure relates to a UV curable coating composition and a process for its preparation.
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 to indicate otherwise.
Design of Experiment: The term “Design of Experiment” refers to the interaction of each ingredient and optimization of the percentage of the ingredients by considering their interaction with each other.
Photoinitiator: The term “photoinitiator” refers to a molecule that creates reactive species (free radicals, cations or anions) when exposed to radiation (UV or visible).
Extender: The term “extender” refers to a chemical substance (inorganic compound) that is added to a paint or coating to improve the properties such as durability, and cost, and to provide different finish.
Flexible Coating: The term “flexible coating” refers to a coating that has ability to bent or flexed without getting cracked or undergoing other failures. It is the coating’s resistance against damaged when the substrate and coating are deformed.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
UV curable coating technology is a fast developing and has shown great potential for application in various fields such as coatings, inks and adhesives, and the like. The UV curable coating technology has numerous advantages over other types of coating compositions such as UV curable coating technology provides an environment friendly process, a high quality product, highly efficient process, excellent energy saving process, low content of volatile organic compound (VOC), less extractable species, stable chemical properties, and good printability on a variety of substrates. The UV curable coating composition are also applied on the heat sensitive substrates, and results in a high printing resolution.
Currently available UV curable technology still needs improvement in terms of curing speed, VOC content, energy consumption, stability of the coating, and in term of scaling-up the production at a commercial scale. Further, the coating carried out by using the conventionally/commercially available UV curable coating composition, is brittle and lacks flexibility.
Therefore, there is felt a need to develop a UV curable coating composition which can overcome 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 UV curable coating composition.
Still another object of the present disclosure is to provide a UV curable coating composition that gives a flexible coating.
Yet another object of the present disclosure is to provide a simple and economic process for the preparation of a UV curable coating composition.
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 relates to a UV curable coating composition and a process for its preparation.
The UV curable coating composition comprises a UV curable coating composition comprises at least one oligomer, at least one monomer, at least photoinitiator, at least one additive, optionally at least one pigment, optionally at least one extender, and optionally at least one fluid medium.
The UV curable coating composition comprises the amounts of the oligomer in the range of 30 mass% to 80 mass%, the monomer in the range of 5 mass% to 40 mass%, the photoinitiator in the range of 1 mass% to 30 mass%, the additive in the range of 1 mass% to 10 mass%, the pigment in the range of 5 mass% to 10 mass%, the extender in the range of 3 mass% to 5 mass%, and the fluid medium in the range of 2 mass% to 8 mass%. All the percentages are with respect to the total mass of the composition.
The present disclosure further relates to a process for preparation of the UV curable coating composition.
The process comprises the step of mixing predetermined amounts of at least one oligomer, at least one monomer; at least photoinitiator, at least one additive, optionally at least one pigment, optionally at least one extender in optionally at least one fluid medium at a predetermined temperature for a predetermined time period in absence of external light or irradiation to obtain the UV curable coating composition.
The present disclosure also relates to a process for curing a UV curable coating composition.
The process comprises the step of applying the coating composition on a substrate to obtain a coated substrate. The coated substrate is irradiated using an UV lamp having intensity in the range of 350 to 450 mJ/cm2 at a speed in the range of 10 to 20 meter/minute for a time period in the range of 1 to 10 seconds.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates FTIR spectrum for the UV curable coating composition comprising phenol crotonaldehyde resin before curing and after curing;
Figure 2 illustrates SEM image of the UV curable overprint varnish coating composition for PVC substrate prepared in accordance with example 2 of the present disclosure;
Figure 3-a illustrates SEM images of the cured ink coating prepared in accordance with example 3 of the present disclosure;
Figure 3-b illustrates high magnification SEM images of the cured ink coating prepared in accordance with example 3 of the present disclosure;
Figure 4-a illustrates photographic image of the printed PVC substrate using UV curable ink coating composition prepared in accordance with example 4-a of the present disclosure;
Figure 4-b illustrates the photographic image of the printed polycarbonate substrate using UV curable ink coating composition prepared in accordance with example 4-b of the present disclosure;
Figure 4-c illustrates the photographic image of the printed card paper substrate using UV curable ink coating composition prepared in accordance with example 4-c of the present disclosure;
Figure 5-a illustrates photographic image of the printed rubber substrate using UV curable ink coating composition prepared in accordance with example 4-d of the present disclosure;
Figure 5-b illustrates the photographic image of the printed the rexine substrate using UV curable ink coating composition prepared in accordance with example 4-d of the present disclosure;
Figure 5-c illustrates the photographic image of the printed metal substrate using UV curable ink coating composition prepared in accordance with example 4-d of the present disclosure;
Figure 5-d illustrates the photographic image of the printed card paper using UV curable ink coating composition prepared in accordance with example 4-d of the present disclosure;
Figure 6 illustrate the simplex design plot for phenol crotonaldehyde oligomer, monomer, and photoinitiators;
Figure 7-a illustrate the main effect plot for the effect of ingredients on the adhesion of UV-Varnish;
Figure 7-b illustrate the interaction plot for phenol crotonaldehyde oligomer, monomer, and photoinitiators;
Figure 8 illustrate the surface interaction plot between phenol crotonaldehyde oligomer, monomer, and photoinitiators;
Figure 9 illustrate the optimization plot from the regression model;
Figure 10-a illustrate the main effect plot for the adhesion on the PVC substrate;
Figure 10-b illustrate the fitted line plot for the adhesion on the PVC substrate;
Figure 11-a illustrate the main effect plot for the adhesion on the polycarbonate substrate;
Figure 11-b illustrate the fitted line plot for the adhesion on the polycarbonate substrate.
DETAILED DESCRIPTION
Embodiments of the present disclosure will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
The UV curable coating technology has numerous advantages such as environmentally friendly process, high quality, high efficiency, excellent energy saving, low VOC, less extractable species, stable chemical properties, good printability on a variety of substrates, as compared to other types of coating compositions. The UV curable coating compositions are also applied on the heat-sensitive substrates, that result in a high printing resolution. Because of these numerous advantages, the UV curable coating compositions find application in various industries such as coatings, inks and adhesives, and the like.
Currently available UV curable technology still needs improvement in terms of curing speed, VOC content, energy consumption, stability of the coating, and in term of scaling-up the production at a commercial scale. Further, the coating prepared by using the currently available UV curable coating composition is brittle and lacks flexibility.
In an aspect, the present disclosure provides a UV curable coating composition.
The UV curable coating composition comprises at least one oligomer, at least one monomer, at least photoinitiator, at least one additive, optionally at least one pigment, optionally at least one extender, and optionally at least one fluid medium.
The UV curable coating composition comprises the amounts of the oligomer in the range of 30 mass% to 80 mass%, the monomer in the range of 5 mass% to 40 mass%, the photoinitiator in the range of 1 mass% to 30 mass%, the additive in the range of 1 mass% to 10 mass%, the pigment in the range of 5 mass% to 10 mass%, the extender in the range of 3 mass% to 5 mass%, and the fluid medium in the range of 2 mass% to 8 mass%. All the percentages are with respect to the total mass of the UV curable coating composition.
In accordance with an embodiment of the present disclosure, the oligomer is at least one selected from acrylate based resin and urethane based resin.
Oligomer provides properties such as adhesion range and flexibility. Oligomers contain polymerizable groups which can undergo polymerization leading to the formation of the coating. Oligomers are the major part of the coating composition, and are therefore responsible for the main properties of the coating composition and for curing the film.
In accordance with an embodiment of the present disclosure, the oligomer is in an amount in the range of 30 mass% to 80 mass% with respect to the total mass of the composition. In an exemplary embodiment, the amount of the oligomer is 43.5 mass% with respect to the total mass of the composition.
In accordance with an embodiment of the present disclosure, a molecular weight of the oligomer is in the range of 500 to 20, 000 Kg/mole.
In accordance with an embodiment of the present disclosure, the acrylate based resin is at least one selected from the group consisting of unsaturated polyester, unsaturated acrylate polyester, acrylated epoxy resin, aliphatic acrylated urethanes, aromatic acrylated urethane, acrylated silicone resin, acrylated polyether, acrylated melamine, epoxy acrylate resin and acrylated oil.
In accordance with an embodiment of the present disclosure, the urethane based resin is at least one selected from the group consisting of aliphatic urethane resin and aliphatic polyurethane acrylate.
In accordance with an embodiment of the present disclosure, the oligomer is phenol crotonaldehyde resin.
In accordance with an embodiment of the present disclosure, the phenol crotonaldehyde resin is in the amount in the range of 40 to 55 mass% with respect to the total mass of the coating composition.
In accordance with an embodiment of the present disclosure, the monomer is at least one selected from the group consisting of vinyl derivative, acrylate ester, difunctional acrylate, triacrylate, tetra-acrylate, penta-acrylate, and allylic derivative.
The main function of the monomer is to tune the viscosity of the coating composition to the desired viscosity. Monomers can also be used as an alternative to fluid medium and reduce the viscosity of the coating composition. Monomer copolymerizes with the oligomer and become integrated into the polymer matrix during the process of curing.
In accordance with an embodiment of the present disclosure, the monomer is in an amount in the range of 5 mass% to 40 mass% with respect to the total mass of the composition. In an exemplary embodiment, the amount of the monomer is 10.6 mass% with respect to the total mass of the composition.
In accordance with an embodiment of the present disclosure, the vinyl derivative is at least one selected from the group consisting of vinyl acetate, N-vinyl pyrrolidone, and N-vinyl caprolactam (NVC). In an exemplary embodiment, the vinyl derivative is N-vinyl pyrrolidone. In another exemplary embodiment, the vinyl derivative is N-vinyl caprolactam (NVC).
In accordance with an embodiment of the present disclosure, wherein the acrylate ester is at least one selected from the group consisting of butyl acrylate, ethyl hexyl acrylate, iso decyl acrylate, iso bornyl acrylate, 2-hydroxy ethyl acrylates, and 2-hydroxy propyl acrylate.
In accordance with an embodiment of the present disclosure, wherein the difunctional acrylate is at least one selected from the group consisting of 1,4-butanedioldiacrylate, 1,6-hexanedioldiacrylate neo-pentylglycoldiacrylate, and diethyleneglycoldiacrylate.
In accordance with an embodiment of the present disclosure, the triacrylate is at least one selected from the group consisting of pentaerythritoltriacrylate, and trimethylolpropanetriacrylate.
In accordance with an embodiment of the present disclosure, the tetra-acrylates is pentaerythritol tetra acrylate.
In accordance with an embodiment of the present disclosure, the penta-acrylate is dipentaerythritol (mono hydroxy) penta-acrylate.
In accordance with an embodiment of the present disclosure, the allylic derivative is at least one selected from the group consisting of triallyl cyanurate, and trimethylol propane triallyl ether.
In accordance with an embodiment of the present disclosure, the photoinitiator is at least one selected from the group consisting of benzophenone, ethyl-4-(dimethylamino) benzoates (EDB), isopropylthioxanthone (ITX), 1-hydroxy cyclohexyl phenyl ketone, 2,4,6-trimethyl benzoyl diphenylphosphine oxide (TPO), 2-Hydroxy-2-methyl propiophenone (Durocare 1173), morpholino propiophenone. In an exemplary embodiment, the photoinitiator is a blend of benzophenone, morpholino propiophenoneethyl-4-(dimethylamino) benzoates (EDB), isopropylthioxanthone (ITX), and 2,4,6-trimethyl benzoyl diphenylphosphine oxide (TPO).
Photoinitiators are organic molecules or chemicals that generate radical species when exposed to UV light. Photoinitiators are vital part of UV-curable composition and coatings formulation, for polymerization reaction to take place. During the UV-curing process, photoinitiators (PIs) are the key component due to their capacity to absorb energy radiation of the appropriate light wavelength and generate active intermediate (free radical or cation) that initiate the prepolymer system into linear polymer or crosslinked network. Many elements in the molecules can motivate radicle formation such as phosphorous, sulfur, and the like. These elements are stabilized with some other carbonyl. There are pi bonding electrons or electron pairs on the heteroatoms that generate the free radicles on the application of the UV light in the reaction mixture of the composition. The amount of photoinitiator required in the coating composition depends on the UV light source, film thickness, and the coating/ink properties. There are two main types of photoinitiators for free radical curing, type I, and type II. Type I photoinitiators undergo cleavage upon irradiation and generate two radicals, of which one is reactive and initiate polymerization. Further, type II photoinitiators upon irradiation form an excited state and abstract an atom/electron from a donor molecule (synergist) who then acts as an initiating species for the polymerization. Different photoinitiators absorb UV light at different wavelengths, as different lamps emit energy in different parts of the spectrum. To achieve the highest efficiency match ? max (peak absorbance: the wavelength photoinitiator absorbs most energy) with UV output of the lamp.
In accordance with an embodiment of the present disclosure, the photoinitiator is in an amount in the range of 1 mass% to 30 mass% with respect to the total mass of the composition. In an exemplary embodiment, the amount of the photoinitiator is 22 mass% with respect to the total mass of the composition.
In accordance with the present disclosure, the coating composition can be colored or colorless. In an embodiment, the coating composition is colourless. In another embodiment, the coating composition is coloured.
In accordance with an embodiment of the present disclosure, the additive is in an amount in the range of 1 mass% to 10 mass% with respect to the total mass of the composition. In an exemplary embodiment, the amount of the additive is 5 mass% with respect to the total mass of the composition.
Methyl diethanolamine (MDEA) is added to adjust the pH and also helps in curing the coating.
Methylethyl ketone oxime (MEK oxime) is used a surface levelling agent which acts by altering the surface energy of the coating composition.
In accordance with an embodiment of the present disclosure, the pigment is at least one selected from the group consisting of cromopthal scarlet RN, yellow pigment, red pigment, and black pigment. In an exemplary embodiment, the pigment is a mixture of cromopthal scarlet RN, yellow pigment, and red pigment.
In accordance with an embodiment of the present disclosure, the pigment is in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the composition. In an exemplary embodiment, the amount of the pigment is 6 mass% with respect to the total mass of the composition.
In accordance with an embodiment of the present disclosure, the extender is at least one selected from the group consisting of silicon dioxide, barium sulphate, and calcium carbonate.
In accordance with an embodiment of the present disclosure, the extender is in an amount in the range of 3 mass% to 5 mass% with respect to the total mass of the composition.
In accordance with an embodiment of the present disclosure, the additive is at least one selected from the group consisting of silicon containing compounds, methyl diethanolamine, and methylethyl ketone oxime (MEK oxime). In an exemplary embodiment, the additive is methyl diethanolamine. In another exemplary embodiment, the additive is methylethyl ketone oxime (MEK oxime).
In accordance with an embodiment of the present disclosure, the fluid medium is at least one selected from the group consisting of N-vinyl pyrrolidone, and N-vinyl caprolactam (NVC). In an exemplary embodiment, the fluid medium is N-vinyl pyrrolidone. In another exemplary embodiment, the fluid medium is N-vinyl caprolactam (NVC).
In accordance with an embodiment of the present disclosure, the fluid medium is in an amount in the range of 2 mass% to 8 mass% with respect to the total mass of the composition. In an exemplary embodiment, the amount of the fluid medium is 6.8 mass% with respect to the total mass of the composition.
In accordance with an embodiment of the present disclosure, a mass ratio of the oligomer to the monomer is in the range of 0.75:1 to 16:1.
In another aspect, the present disclosure relates to a process for preparation of the UV curable coating composition.
The process comprises the step of mixing predetermined amounts of at least one oligomer, at least one monomer; at least photoinitiator, at least one additive, optionally at least one pigment, and optionally at least one extender in optionally at least one fluid medium at a predetermined temperature for a predetermined time period in absence of external light or irradiation to obtain the UV curable coating composition.
In accordance with an embodiment of the present disclosure, the mixing is carried out by any suitable mixing means.
In accordance with an embodiment of the present disclosure, the mixing is carried out in dark conditions.
In accordance with an embodiment of the present disclosure, the predetermined temperature is in the range of 20 °C to 50 °C and predetermined time period is in the range of 1 hr to 2 hr. In an exemplary embodiment, the predetermined temperature is 30 °C and the predetermined time period is 1.5 hr.
In accordance with an embodiment of the present disclosure, the at least one oligomer, at least one monomer, at least photoinitiator, at least one additive, optionally at least one pigment, and optionally at least one extender are grinded to a particle size in the range of 2 ?m to 5 ?m to form a homogeneous mixture.
The present disclosure also relates to a process for curing a UV curable coating composition.
The process comprises the step of applying the coating composition on a substrate to obtain a coated substrate. A thickness of the coating on the substrate is in the range of 5 ?m to 10 ?m.
The coated substrate is irradiated using an UV lamp having intensity in the range of 350 to 450 mJ/cm2 at a speed in the range of 10 to 20 meter/minute for a time period in the range of 1 to 10 seconds.
In accordance with an embodiment of the present disclosure, the substrate is selected from paper, glass, polyvinyl chloride, polycarbonate, rubber, rexine, and painted metal.
In accordance with the present disclosure, a complete adhesion was observed at 43.3% of phenol crotonaldehyde oligomer, 17.5% of monomer, and 26% of photoinitiator blend.
In accordance with an embodiment of the present disclosure, the UV curable coating composition is used in the form of varnish, and ink composition.
The coating prepared by using the UV curable coating composition of the present disclosure has excellent adhesion to the substrate, excellent gloss properties, flexible and economical.
The UV curable ink dry by crosslinking/polymerization of the ingredients of the coating composition. The UV curable coating composition of the present disclosure do not have volatile organic components, which is hazardous, carcinogenic and affect human health. The UV curable coating composition of the present disclosure does not require long drying time and dry in fraction of seconds.
The foregoing description of the embodiments has been provided for purposes of illustration and is not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS
Example 1: UV curable varnish coating composition in accordance with the present disclosure
UV curable coating composition was prepared by mixing 43.5 gm of phenol crotonaldehyde resin oligomer), 10.6 gm of epoxy acrylate resin , 10.6 gm of N-vinyl caprolactum (monomer), 4.2 gm of photoinitiator 2-Hydroxy-2-methyl propiophenone (durocure 1173), and 5 gm of N-vinyl pyrrilidone at 30 oC to obtain a mixture. The viscosity of the mixture was then adjusted by adding 26.1 gm of N-vinyl pyrrilidone (26.1 mass%) as a fluid medium into the mixture.
Process of curing the UV curable coating composition in accordance with the present disclosure
The UV curable varnish coating composition as prepared above, was applied on a clean glass slide of the size 5 cm x 10 cm having a thickness of 35 µm and then exposed to 400 mJ/cm2 dose of UV irradiation by using the UV Systems with speed 15 meters/min to form the glass slide coated with the composition. The glass slide coated with the composition was allowed to pass through the UV radiation light and the composition was cured within 4 second to obtain the coated surface of the glass slide.
Similarly, glass plates were coated by using the composition of as prepared above and exposed to a high-pressure mercury lamp (UV lamp) equipped with a conveyor and a power of the lamp was set to 400 mJ/cm2, and the conveyor speed was 15 meters/min.
FTIR characterization of coating composition of example 1
Coated glass substrates as prepared above were characterized using FTIR. spectra as shown in figure 1. Figure 1 demonstrates the signal at 1600 cm-1, which attributed to the C=C bond from phenol crotonaldehyde (PC) oligomer, and con?rmed the presence of C=C functional groups in the phenol crotonaldehyde oligomer. Moreover, the signals at 1600 cm-1 showed that the C=C bond remained before and after the formation of the coating composition before the step of curing. However, after the step of curing signals at 1600 cm-1 disappeared indicating the conversion of unsaturation in the phenol crotonaldehyde resin to saturated form via cross-linking with monomer and 100% cross-linking was observed.
Example 2: UV curable overprint varnish coating composition for PVC substrate in accordance with the present disclosure
The UV curable overprint varnish composition for PVC substrate was prepared by using the procedure similar to that in example 1 except the raw materials as shown in table 1 below were used.
Table 1: Components used for preparation of the UV curable overprint varnish composition for PVC substrate
Sr. No Raw Material Percentage (mass %)
1 Phenol Crotonaldehyde resin (Oligomer) 43.5
2 Epoxy Acrylate (Oligomer) 10.6
3 N-Vinyl caprolactam (NVC) (Monomer) 10.6
4 Methyl diethanolamine (additive) 4.5
5 Benzophenone (photoinitiator) 7.5
6 Morpholino propiophenone (photoinitiator) 2.16
7 Ethyl-4-(dimethylamino)benzoate (EDB) (photoinitiator) 2.16
8 ITX (photoinitator) 2.16
9 2-Hydroxy-2-methyl propiophenone (Durocure 1173) (photoinitator) 4.2
10 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) (photoinitiator) 3.6
11 N-vinyl pyrrolidone (fluid medium) 6.8
12 MEK Oxime (additive) 2
Total 100

The sticky transparent liquid resulted from the mixing of the components of Table 1 indicated the formation of the UV curable overprint varnish coating composition of the present disclosure. The viscosity of the UV curable overprint varnish composition was adjusted by using N-vinyl caprolactum (fluid medium).
The UV curable overprint varnish coating composition for PVC substrate was applied on the PVC substrate and cured by using UV light. The UV curable overprint varnish coated PVC substrate was characterized by using SEM as shown in figure 2 (SEM image taken before curing). The SEM image of the varnish indicated the uniform glossy and transparent surface of the homogenous mixture of coating composition of example 2. Figure 2a indicated that the formation of the UV curable overprint varnish composition has the excellent glossiness and was free from any impurity. The high magnification image of the same material is also shown in the Figure 2b which indicated that the UV curable overprint varnish coating composition and was free from wrinkles.
Example 3: UV curable ink coating composition in accordance with the present disclosure
The UV curable ink coating composition was prepared by first mixing the 42.5 gm phenol-crotonaldehyde oligomer, 10.6 gm of epoxy acrylate, 6 gm of red pigments, 10 gm of N-vinyl caprolactum (monomer), 1.5 gm of wax, and 3.2 gm of methyl di-ethanolamine (additive) under stirring for 10 min to obtain a premixture. Then the premixure was allowed to pass through a Tripple Roll Mill (TRM) three times to obtain a reaction mixture. The grinding of the reaction mixture was checked on the Hegman gauge. The reaction mixture was further allowed to remix with 7 gm of benzophenone (photoinitiator), 2 gm of Ethyl-4-(dimethylamino) benzoate (EDB), 2 gm of ITX (photoinitiator), 4.2 gm of 2-Hydroxy-2-methyl propiophenone (Durocure 1173) (photoinitiator), and 3.6 gm of TPO (Photoiniator) to form a postmixture. The postmixture was stirred for 30 minutes at 30 oC to obtain a homogenous mixture of red ink. This stirring step was carried in the absence of any external radiation or light because of the presence of the light sensitive material. Similarly, the four pigments of desired colour (CMYK) can also be used in composition comprising phenol-crotonaldehyde resin. Components used for preparation the UV curable ink composition with corresponding percentages are shown in Table 2
Table 2: Components used for the preparation of the UV curable ink composition
Sr. No Raw Material Percentage (mass %)
1 Phenol –Crotonaldehyde (oligomer) 42.5
2 Epoxy Acrylate ( oligomer) 10.6
3 Mixture of Cromophtal Scarlet RN, yellow shade, Red Pigment 5
4 Cromine Red Pigment 1
5 N-Vinyl Caprolactam (monomer) 10
6 Methyl diethanolamine (MDEA) (additive) 3.2
7 Polyethylene wax (additive) 3
8 Benzophenone (photoinitiator) 7
9 Morpholino propiophenone (photoinitiator) 2
10 Ethyl-4-(dimethylamino)benzoate(EDB) (photoinitiator) 2
11 ITX ( photoinitators) 2
12 2-Hydroxy-2-methyl propiophenone (Darocure 1173) (photoinitiator) 4.2
13 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) (photoinitiator) 3.6
14 N-vinyl pyrrolidone (fluid medium) 2
15 MEK Oxime (additive) 2
Total 100
The UV curable ink composition was used for printing and cured by using UV light. The cured ink coating of example 3 was characterized by using FTIR, which showed similar results as that in example 1 (figure 1) were obtained indicating that the step of curing converted unsaturation in the phenol crotonaldehyde resin to saturated form via crosslinking with monomer; thereby obtaining 100% crosslinking. Further, cured ink coating was characterized using SEM imaging as shown in figure 3 (figure 3-a: SEM of cured ink and figure 3-b is of uncured ink) which showed the uniform size and morphology of the ink.
Example 4: UV curable ink coating composition for various substrates in accordance with the present disclosure
a) UV curable ink coating composition for PVC substrate:
The UV curable ink composition for PVC substrate was prepared by mixing the component as shown in Table 3 below:
Table 3: Components used for the preparation of the UV curable ink composition for PVC substrate
Sr. No Raw
Material Percentage
(mass %)
1 Phenol Crotonaldehyde (oligomer) 42.5
2 Epoxy Acrylate (oligomer) 10.6
3 Mixture of Cromophtal Scarlet RN, yellow shade, Red Pigment 6
4 N-Vinyl Caprolactum (monomer) 10
5 Methyl diethanolamine (additive) 3
6 Benzophenone (photoinitiator) 7
7 Morpholino propiophenone (photinitiator) 2
8 Ethyl-4-(dimethylamino)benzoate(EDB) (photoinitiator) 2
9 ITX ( photoinitiator) 2
10 2-Hydroxy-2-methyl propiophenone (Duracure 1173) (photoinitaitor) 4.2
11 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) (photoinitiator) 3.6
12 N-vinyl pyrrolidone (monomer as well as fluid medium) 3.4
13 MEK Oxime (additive) 2
Total 100

The UV curable ink composition for PVC substrate as prepared using the composition of table 3 was suitable for the excellent adhesion and for fast curing on the PVC substrate. The higher surface energy of the PVC substrates that matched with the surface tension of the UV curable ink composition i.e., by lowering the surface tension of the ink facilitates, the good adhesion. N-vinyl caprolactam (NVC) and methyl diethanolamine played an important in manipulating the surface energy of the substrate. In UV curable ink composition for PVC substrate, the respective weight percentages of phenol crotonaldehyde resin, epoxy acrylate resin and NVC monomer is responsible for the excellent adhesion on the PVC substrate. The role of epoxy acrylate resin was to boost the adhesion between the ink composition and the PVC substrate, and the phenol crotonaldehyde resin was majorly responsible for curing of the ink. Combination of the photoinitiators such as benzophenone was used to generate the radicles for the quick crosslinking process. The main role of MEK in UV curable ink composition was to get the leveling properties in film.
Printing of the UV curable ink coating composition of the present disclosure on the PVC substrate:
The UV curable ink composition was printed on the PVC substrate by using a screen of 150 mesh size (screen printing) 1 stroke and the printed substrate were allowed to pass through a mercury lamp (UV light) for 3-4 second with 15 meters/minute belt speed. The UV irradiation was applied at full power, with the lamp set at 400 mJ/cm2 and the intensity was measured with the help of a radiometer. Photographic image of the printed PVC substrate is shown in figure 4-a. Further, the tape test was performed to check the adhesion of the printed ink on PVC.
Tape Test:
For coatings up to 2.0 mils thick, eleven incisions are made that are spaced 1 mm apart. For printing ink between 2.0 mils and 5.0 mils thick, six incisions are spaced 2 mm apart. Once the incisions are made, a pressure sensitive tape (with adhesive properties conforming to the requirements of the standard) is applied over the incisions and pressed in place using a pencil eraser. Following a brief “recovery” period of about 60 seconds the tape is removed by grasping the free end of the tape and pulling it off rapidly back upon itself at as close to an angle of 180° as possible. After removal of the tape, the amount of ink removed from the PVC substrate or underlying ink is rated. The coated ink surface was evaluated and not the back of the tape, since coating debris from the incisions is often removed by the tape. Adhesion is rated based on the scale provided in the ASTM standard.
The printed ink showed excellent adhesion to the PVC substrate and had a glossy nature.
b) UV curable ink coating composition for polycarbonate substrate:
The UV curable ink composition for polycarbonate substrate was prepared by mixing the components as shown in Table 4 below. Further, the UV curable ink composition for polycarbonate substrate was printed on the polycarbonate substrate by using the similar method as described in example 4-a.
Table 4: Components used for the preparation of the UV curable ink coating composition for polycarbonate substrate
Sr. No Raw
Material Percentage
(%)
1 Phenol Crotonaldehyde resin (oligomer) 50
2 Epoxy Acrylate resin (oligomer) 11
3 Mixture of Cromophtal Scarlet RN, yellow shade, Red Pigment 5
4 Methyl diethanolamine(MDEA) (additive) 4
5 Benzophenone (photoinitiator) 7
6 Morpholino propiophenone (photinitiator) 2
7 Ethyl-4-(dimethylamino)benzoate(EDB) (photoinitiator) 2
8 ITX ( photoinitators) 2
9 2-Hydroxy-2-methyl propiophenone (Durocure 1173) (photoinitiator) 4.2
10 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) (photoinitiator) 3.6
11 N-vinyl pyrrolidone (monomer as well as fluid medium) 7.4
12 MEK Oxime (additive) 2
Total 100
The components of the UV curable ink coating composition for polycarbonate substrate were chosen in such a way that the surface energy of the ink composition and polycarbonate substrate matches with each other. The ink composition of desired color (CMYK) was prepared by using the corresponding pigment in the composition. The photographic image of the printed polycarbonate substrate is shown in figure 4-b. Further, the tape test was performed to check the adhesion of the printed ink on the polycarbonate substrate. The printed ink showed an excellent adhesion to the polycarbonate substrate and had a glossy nature.
c) UV curable ink coating composition of the present disclosure for card paper:
The UV curable ink coating composition for card paper substrate was prepared by mixing the component as shown in table 5 below. Further, the UV curable ink composition for card paper was printed on the card paper by using similar methods as described in example 4-a.
Table 5: Components used for preparation the UV curable ink composition for card paper substrate:
Sr. No Raw
Material Percentage
(%)
1 Phenol Crotonaldehyde (Oligomer) 60
Mixture of Cromophtal Scarlet RN, yellow shade, Red Pigment 6
4 Methyl diethanolamine (additive) 4
5 Benzophenone (photoinitiator) 7
6 Morpholino propiophenone (photoinitiator) 2
7 Ethyl-4-(dimethylamino)benzoate(EDB) (photoinitiator) 2
8 ITX ( photoinitiator) 2
9 2-Hydroxy-2-methyl propiophenone (Durocure 1173) (photoinitiator) 4.2
10 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) (photoinitiator) 3.6
11 N-vinyl pyrrolidone (monomer as well as fluid medium) 7.4
12 MEK Oxime (additive) 2
Total 100

The UV curable ink composition for card paper did not require epoxy acrylate to be included in the composition for providing adhesion to the card paper substrate because of the high surface energy of the card paper substrate. Phenol crotonaldehyde oligomer was sufficient to provide excellent adhesion for the ink composition to the card paper. The photographic image of the printed card paper is shown in figure 4-c. Further, the tape test was performed to check the adhesion of the printed ink on card paper. The printed ink showed excellent adhesion to the card paper and had a glossy nature.
Adhesion of UV curable ink coating composition on card paper at different percentages of PC-Oligomer is provided herein table 6.
Table 6. Adhesion of UV curable ink coating composition on card paper at different percentages of PC-Oligomer
Phenol crotonaldehyde oligomer
(mass%) Adhesion
45 Fail
48 Fail
51 Fail
53 Fail
56 Fail
59 Pass
62 Pass
65 Pass

UV curable ink coating composition showed a better adhesion when the amount of PC-oligomer was in the range of 59 to 65 mass%.
Thickness of the printed ink and cured ink on the surface of various surfaces were measured and it is summarized in table 7 below:
Table 7: Measurement of the film thicknesses on printed ink on various substrates
Sr. No. Substrates Film thickness (micron)
1 Card paper 6
2 PVC 6 to 8
3 Polycarbonate 5
Further, the UV curable ink coating composition of the present disclosure was also printed on various substrates such as rubber substrate, rexine, painted metal, and card paper. The ink composition was printed on the various substrates by using the procedure described in example 4-a. Photographic image of ink printed on rubber substrate, rexine, painted metal, and card paper is shown in figures 5-a, 5-b, 5-c and 5-d, respectively.
Example 5: Statistical method for the formulation of UV varnish coating composition by design of experiment (DOE)
The UV curable varnish coating composition as prepared in example 1 was considered as a reference composition and few levels were experimentally evaluated which assisted to decide the levels of factors. Design-of-experiments (DOE) for the UV curable varnish coating composition considered three levels of the phenol crotonaldehyde oligomer percentage, three levels for monomer percentage, and three levels for photoinitiators percentage as shown in Table 8 below.
Table 8. Variables and levels for the design of the experiment
Sr. No. Variables Level-1 Level-2 Level 3
1 Phenol crotonaldehyde (PC) oligomer 41.5% 43.5% 45.5%
2 Monomer 14.5% 17.5 % 20.5%
3 Blend of Photoiniatators 24% 26% 29%

To evaluate the effect of phenol crotonaldehyde oligomer, the percentage of epoxy acrylate was kept constant which was sufficient enough i.e. 10.6 % to boost the hardness of the ink film. The DOE is as shown in Table 9 below, which provided the total 14 UV curable varnish coating compositions (including 2 replicates). These 14 UV curable varnish coating compositions were evaluated for the adhesion of ink.
Table 9. Phenol crotonaldehyde oligomer based formulations based on mixture design
Std. Order Phenol crotonaldehyde oligomers Monomers Photoinitiators
1 41.5 17.5 28
2 41.5 17.5 28
3 41.5 20.5 25
4 41.5 20.5 25
5 43.5 17.5 26
6 43.5 17.5 26
7 43.5 14.5 29
8 43.5 14.5 29
9 43.5 20.5 23
10 43.5 20.5 23
11 45.5 14.5 27
12 45.5 14.5 27
13 45.5 17.5 24
14 45.5 17.5 24

The Minitab 17 statistical software was used to statistically analyze the data and for the prediction of response.
Simplex design plot: A simplex design plot was used to visualize and understand the mixture design space. Minitab software plots the mixture points on the triangular axes as shown in Figure 6. The vertices of the triangle showed the three pure mixtures for each component (phenol crotonaldehyde oligomer, monomer, and photoinitiator). The midpoint of each edge of the triangle represents the three binary blends. Inside the triangle, blends were for three ingredients, but are not in equal proportion. The blend at one central point or centroid represents the proportions of all three ingredients present in the UV curable coating composition.
Example 6: Statistical analysis for adhesion of the UV curable ink coating composition on PVC substrate
Design of experiments for different UV cured coating compositions was prepared by mixing 42.5 mass% of phenol crotonaldehyde (PC) resin, 10.6 mass% of epoxy acrylate, 10 mass% of reactive diluent N-Vinyl caprolactam (NVC) monomer, and 20.8 mass% of photoinitiator and 3.4 mass% of N-vinyl pyrrolidone (NVP) to obtain a mixture. All ingredients were added one by one. The role of the methylethyl ketone (MEK) Oxime was very significant to set the leveling film surface. The resulting mixture was stirred well to dissolve each component in the mixture at room temperature (RT) with a controlled stirring speed of the stirrer. After complete dissolution of the components, the liquid varnish composition was obtained and the viscosity of the liquid varnish composition was tuned by using 10 mass% of N-Vinyl caprolactam (NVC) and stored for 15 to 20 minutes at room temperature for settlement. The UV curable ink composition was used for printing on PVC substrate and cured by using UV light. The UV curable ink composition for PVC was printed the PVC substrate by similar method as described in experiment 4-a. Further, a tape test was performed to check the adhesion of the printed ink on the PVC substrate. ASTM Adhesion test method F2252 / F2252M was used to measure the adhesion of ink on the PVC substrate.
Figure 7-a provides a graph plot that shows the effect of ingredients on the adhesion of UV curable varnish coating composition of example 1. This plot reflects the data means at the various levels of each factor, with a reference line drawn at the grand mean of the response data. The main effect plot showed that the adhesion of UV-Varnish on the PVC substrate is obtained at the higher levels of oligomers. Perfect blend (ratio) of oligomer: monomers: photoinitiators is required to form the complete cross-linking between oligomers and monomers. The percentage for a blend of photoinitiators used in the formulation should sufficient enough to initiates the polymerization process to quickly reach the final crosslinked product. Complete adhesion was observed at 43.3% of PC oligomer, 17.5% of monomer, and 26% of photoinitiator blend. From Figure 7-a, it is evident that there was complete crosslinking occurred in varnish. This UV curable coating composition provided complete adhesion of varnish and also improved the gloss due to the higher curing rate. Below and above the 26 mass% blend of photoinitiators, less and over curing was observed, which affects the adhesion of the varnish layer as well as gloss of the printed substrate.
Figure 7-b shows the interaction plot for all three ingredients. The interaction plot considers the means for each level of a factor with the level of the second factor held constant. An interaction plot is a plot of means for each level of a factor with the level of a second factor held constant. Interaction plots are useful for judging the presence of interaction. Interaction is present when the response at a factor level depends upon the level(s) of other factors. Parallel lines in an interaction plot indicated no interaction. The greater the departure of the lines from the parallel state, the higher the degree of interaction. Figure 8 shows the surface plot of photoinitiators vs monomers vs phenol crotonaldehyde oligomers. From Figure 8, it is evident that the interaction takes place between oligomer, monomers, photoinitiators as lines are not parallel to each other.
Optimization from the Regression Model: Figure 9 shows the optimization plot for complete adhesion. The plot shows the effect of phenol crotonaldehyde oligomer, monomer, and photoinitiator on the adhesion of UV varnish on PVC substrate. The vertical red lines on the graph indicate the current factor setting. The number displayed in a square bracket at the top of a column represents the current factor level setting. The horizontal dash lines represent the response i.e. adhesion for the current factor level. From Figure 9, it is evident that, at 43.72% of PC oligomer, 17.07% of monomer, and 26.20% of photoinitiator provides the complete adhesion of UV-varnish on PVC substrate
Figure 9 shows the optimization plot. The plot shows the effect of PC-Oligomer, Monomer, and Photoinitiator on the adhesion of UV varnish on PVC substrate. The vertical red lines on the graph indicate the current factor setting. The number displayed in a square bracket at the top of a column represents the current factor level setting. The horizontal dash lines represent the response i.e. adhesion for the current factor level. Figure 9 explains that at 43.72 % of PC-oligomer, 17.07% of monomer, and 26.20% of photoinitiator provides the complete adhesion of UV-varnish on PVC substrate. Additionally, the confidence interval indicates the 95% confidence that the adhesion of UV cure varnish is 100% at these optimized settings as the composite desirability observed is 1.
Validation Trial:
A validation trial was formulated for the optimized values as 43.5% of phenol crotonaldehyde oligomer, 10.5% of epoxy acrylate oligomer, 3% of additive, 17% of monomer and 26% of photoinitiator. The UV curable varnish coating composition provides complete adhesion and 85% gloss on the PVC substrate.
Figure 10-a shows main effect plot for the adhesion on the PVC substrate.
Figure 10-b shows fitted line plot for the adhesion on the PVC substrate.
Figure 11-a shows main effect plot for the adhesion on the polycarbonate substrate.
Figure 11-b shows fitted line plot for the adhesion on the polycarbonate substrate.
From Figures 10 (a, b) and Figures 11 (a, b), it is evident that, increase in the percentage of phenol crotonaldehyde oligomer increases the adhesion of ink on PVC substrate. A higher percentage of phenol crotonaldehyde oligomers was required for the adhesion of polycarbonate substrate as compared to PVC substrate.
The composition of the optimized UV curable ink coating composition printable on the PVC substrate and on the polycarbonate substrate is provided herein below Table 10.
Table 10. The optimized UV curable ink coating composition for PVC and polycarbonate substrate.
Sr. No Raw Material For PVC substrate (%) For Polycarbonate substrate (%)
1 Phenol crotonaldehyde oligomer 43.5 50
2 Epoxy Acrylate 10.6 10.6
3 Blend of Monomer 13.9 7.4
4 Pigment 6 6
5 Blend of Photoinitiator 24 24
6 Additives 2.0 2.0
The optimized UV curable ink coating composition was analyzed and confirmed by using FTIR, which showed the similar observations as provided in Figure 1.
TECHNICAL ADVANCEMENTS AND ECONOMIC SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a UV curable coating composition that has:
• stable and flexible coating prepared by using the UV curable coating composition;
• excellent adhesion to the substrate;
• glossy in nature; and
• simple and economical process for preparation of a UV curable coating composition and a coating therefrom.
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.
One of the objects of the Patent Law is to provide protection to new technologies in all fields and domain of technologies. The new technologies shall or may contribute in the country economy growth by way of involvement of new efficient and quality method or product manufacturing in India.
To provide the protection of new technologies by patenting the product or process will contribute significant for innovation development in the country. Further by granting patent the patentee can contribute in manufacturing the new product or new process of manufacturing by himself or by technology collaboration or through the licensing.
The applicant submits that the present disclosure will contribute in country economy, which is one of the purposes to enact the Patents Act, 1970. The product in accordance with present invention will be in great demand in country and worldwide due to novel technical features of a present invention is a technical advancement in the coating composition. The technology in accordance with present disclosure will provide product cheaper, saving in time of total process of manufacturing. The saving in production time will improve the productivity, and cost cutting of the product, which will directly contribute to economy of the country.
The product will contribute new concept in the coating composition wherein patented process/product will be used. The present disclosure will replace the whole concept of coating compositions being used in this area from decades. The product is developed in the national interest and will contribute to country economy.
The economy significance details requirement may be called during the examination. Only after filing of this Patent application, the applicant can work publically related to present disclosure product/process/method. The applicant will disclose all the details related to the economic significance contribution after the protection of invention.
,CLAIMS:WE CLAIM:
1. A UV curable coating composition comprising:
• at least one oligomer;
• at least one monomer;
• at least photoinitiator;
• at least one additive;
• optionally at least one pigment;
• optionally at least one extender; and
• optionally at least one fluid medium.
2. The composition as claimed in claim 1, wherein the amount of
a. said oligomer is in the range of 30 mass% to 80 mass%;
b. said monomer is in the range of 5 mass% to 40 mass%;
c. said photoinitiator is in the range of 1 mass% to 30 mass%;
d. said additive is in the range of 1 mass% to 10 mass%;
e. said pigment is in the range of 5 mass% to 10 mass%;
f. said extender is in the range of 3 mass% to 5 mass%; and
g. said fluid medium is in the range of 2 mass% to 8 mass%;
wherein all the percentages are with respect to the total mass of the composition.
3. The composition as claimed in claim 1, wherein said oligomer is at least one selected from acrylate based resin and urethane based resin.
4. The composition as claimed in claim 1, wherein a molecular weight of said oligomer is in the range of 500 to 20, 000 Kg/mole.
5. The composition as claimed in claim 3, wherein said acrylate based resin is at least one selected from the group consisting of unsaturated polyester, unsaturated acrylate polyester, acrylated epoxy resin, aliphatic acrylated urethanes, aromatic acrylated urethanes, acrylated silicone resins, acrylated polyether, acrylated melamine, epoxy acrylate resin and acrylated oils; and said urethane based resin is at least one selected from the group consisting of aliphatic urethane resin and aliphatic polyurethane acrylate.
6. The composition as claimed in claim 1, wherein said oligomer is phenol crotonaldehyde resin; and the phenol crotonaldehyde resin is in the amount in the range of 40 to 55 mass% with respect to the total mass of the coating composition.
7. The composition as claimed in claim 1, wherein said monomer is at least one selected from the group consisting of vinyl derivative, acrylate ester, difunctional acrylate, triacrylate, tetra-acrylate, penta-acrylate, and allylic derivative.
8. The composition as claimed in claim 7, wherein said vinyl derivative is at least one selected from the group consisting of vinyl acetate, N-vinyl pyrrolidone, and N-vinyl caprolactam (NVC); said acrylate ester is at least one selected from the group consisting of butyl acrylate, ethyl hexyl acrylate, iso decyl acrylate, iso bornyl acrylate, 2-hydroxy ethyl acrylates, and 2-hydroxy propyl acrylate; said difunctional acrylate is at least one selected from the group consisting of 1,4-butanedioldiacrylate, 1,6-hexanedioldiacrylate neo-pentylglycoldiacrylate, and diethyleneglycoldiacrylate; said triacrylate is at least one selected from the group consisting of pentaerythritoltriacrylate, and trimethylolpropanetriacrylate; said tetra-acrylates is pentaerythritol tetra acrylate; said penta-acrylate is dipentaerythritol (mono hydroxy) penta-acrylate; and said allylic derivative is at least one selected from the group consisting of triallyl cyanurate, and trimethylol propane triallyl ether.
9. The composition as claimed in claim 1, wherein said photoinitiator is at least one selected from the group consisting of benzophenone, ethyl-4-(dimethylamino) benzoates (EDB), isopropylthioxanthone (ITX), 1-hydroxy cyclohexyl phenyl ketone, 2,4,6-trimethyl benzoyl diphenylphosphine oxide (TPO), 2-Hydroxy-2-methyl propiophenone, and morpholino propiophenone.
10. The composition as claimed in claim 1, wherein said pigment is at least one selected from the group consisting of cromopthal scarlet RN, yellow pigment, red pigment, and black pigment.
11. The composition as claimed in claim 1, wherein said extender is at least one selected from the group consisting of silicon dioxide, barium sulphate, and calcium carbonate.
12. The composition as claimed in claim 1, wherein said additive is at least one selected from the group consisting of silicon containing compounds, methyl diethanolamine, and methylethyl ketone oxime (MEK oxime).
13. The composition as claimed in claim 1, wherein said fluid medium is at least one selected from the group consisting of N-vinyl pyrrolidone, and N-vinyl caprolactam (NVC).
14. The composition as claimed in claim 1, wherein a mass ratio of said oligomer to said monomer is in the range of 0.75:1 to 16:1.
15. A process for the preparation of a UV curable coating composition, said process comprising mixing predetermined amounts of at least one oligomer; at least one monomer; at least photoinitiator, at least one additive, optionally at least one pigment, and optionally at least one extender in optionally at least one fluid medium at a predetermined temperature for a predetermined time period in absence of external light or irradiation to obtain the UV curable coating composition.
16. The process as claimed in claim 15, wherein said predetermined temperature is in the range of 20 °C to 50 °C; said predetermined time period is in the range of 1 hr to 2 hr.
17. The process as claimed in claim 15, wherein said at least one oligomer; at least one monomer; at least photoinitiator, at least one additive, optionally at least one pigment, and optionally at least one extender are grinded to a particle size in the range of 2 ?m to 5 ?m to form the homogeneous mixture.
18. The process as claimed in claim 15, wherein said UV curable coating composition is applied on a substrate to obtain a coated substrate, wherein a thickness of said coating on said substrate is in the range of 5 ?m to 10 ?m; and irradiating said coated substrate by using an UV lamp having intensity in the range of 350 to 450 mJ/cm2 at a speed in the range of 10 to 20 meter/minute for a time period in the range of 1 to 10 seconds.

Dated this 31st day of December, 2021

___________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI