DESC:FIELD
The present disclosure relates to a coating composition and a process for its preparation. Particularly, the present disclosure relates to an anti-reflective and anti-soiling coating composition for glass and solar panels.
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 indicate otherwise.
Solar panel: A solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame. Solar panels capture sunlight as a source of radiant energy, which is converted into electric energy in the form of direct current (DC) electricity.
Solar cell: A solar cell or photovoltaic cell, is an electronic device which converts the light energy directly into electricity by the photovoltaic effect.
Photovoltaic effect: The photovoltaic effect is a process that generates voltage or electric current in a photovoltaic cell when it is exposed to sunlight.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Solar energy has gained importance as a green and sustainable form of electricity generation. Solar energy is converted into electrical energy using solar panels. Dust deposition on the solar panels reduces the light transmission to the solar cell and results in reduced efficiency of the solar cell. Further, reflection of light at the glass-air interface leads to lower transmission of light to the solar cell and hence lower efficiency of the solar cell. Therefore, the cover glasses on the solar panels require an anti-reflective and anti-soiling coating.
Conventionally, in order to achieve the anti-reflective and anti-soiling properties, a low refractive index single layer coating such as coating of magnesium fluoride is applied to the glass of the solar panel. However, the conventional single layer coatings are not robust and can get damaged. Alternatively, multilayer coatings are also applied to the solar panels which involve complex deposition techniques such as vapor deposition and electrodeposition which require sophisticated and expensive equipments. Further, in order to reduce the refractive index of the coating on the glass of the solar panel, nanoparticles are externally added to make the surface of the coating rough or porous. Still further, in order to achieve anti-soiling property and low surface energy of the coating on the glass of solar panels, post treatment with fluorinated compounds such as fluorosilanes is carried out. However, additional use of nanoparticles and post treatment with fluorinated compounds adds additional steps and is not cost effective.
There is, therefore, felt a need to develop a coating composition that mitigates the drawback mentioned herein above or at least provides a useful alternative.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a coating composition.
Another object of the present disclosure is to provide a coating composition that can be applied in a single coat.
Yet another object of the present disclosure is to provide a coating composition that has anti-reflective and anti-soiling property.
Still another object of the present disclosure is to provide a coating composition that can be applied using conventional application techniques.
Yet another object of the present disclosure is to provide a coating composition that does not require the external addition of nanoparticles and post treatment with fluorinated compounds.
Still another object of the present disclosure is to provide a simple and an economic process for the preparation of a 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
A coating composition comprises 0.25 wt. % to 2 wt. % of organic silane, 0.1 wt. % to 1 wt. % of inorganic silane, 0.1 wt. % to 0.5 wt. % of a dispersing agent, 0.01 wt. % to 0.1 wt. % of a catalyst, 0.001 wt. % to 0.05 wt. % amine functional compound; and q.s fluid medium wherein wt% of each ingredient is with respect to the total weight of the coating composition.
The organic silane is at least one selected from the group consisting of monomers/oligomers of alkyl alkoxy silanes, alkyl phenyl alkoxy silanes, amino alkoxy silanes, epoxy alkoxy silanes, mercapto alkoxy silanes, isocyanto alkoxy silanes and their corresponding polysiloxanes.
The alkyl alkoxy silanes are selected from the group consisting of ethyl methoxy polysiloxane, methyl ethoxy polysiloxane, methyl phenyl methoxy polysiloxane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, phenyltriethoxysilane, trialkoxyarylsilanes, dimethyldimethoxysilane and trimethylmethoxysilane.
The vinyl alkoxy silanes are selected from the group consisting of vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane and vinyldimethylethoxysilane.
The amino alkoxy silanes are selected from the group consisting of gamma-aminopropyl triethyoxysilane and gamma-aminopropyl trimethoxysilane.

The epoxy alkoxy silanes are selected from the group consisting of gamma- glycidoxypropyl trimethoxysilane and gamma-glycidoxypropyl triethoxysilane.

The mercapto alkoxy silanes are selected from the group consisting of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane.

The isocyanato alkoxy silanes are selected from the group consisting of gamma- isocyanopropyl triethoxysilane, gamma-isocyanopropyl trimethoxysilane or mixtures thereof.
The inorganic silane is at least one selected from the group consisting of monomers/oligomers of alkyl silicates and tetraalkoxysilanes.
The alkyl silicates are selected from the group consisting of tetraethyl orthosilicates, tetramethyl orthosilicates and their oligomers and tetraalkoxysilanes are selected from the group consisting of tetramethoxysilanes, tetraethoxysilanes, tetraisopropoxy silanes and tetra t-butoxy silanes.
The dispersing agent is selected from the group consisting of hydroxy functional polymer, acid functional polymer, amine functional polymer and acid and amine functional polymer and their salt.
The acid functional polymer is selected from the group consisting of phosphoric acid based polyester, acrylic acid or methacrylic acid containing acrylic polymer, acrylic or methacrylic acid containing styrene acrylic polymer, maleic acid grafted vinyl polymers.
The catalyst is selected from the group consisting of organic acid, organic base organotin, organotitanium, organocobalt, organozinc, organobismuth and, organozirconium compounds.
The organic acid is selected from the group consisting of p-toluene sulphonic acid, methanesulphonic acid, acetic acid, and oxalic acid.
The organic base is selected from the group consisting of ammonia, triethylamine, monoethanolamine.
The organotitanium compounds are selected from the group consisting of titanates such as tetra (isopropyl) titanate and tetrabutyl titanate.
The organotin compounds are selected from the group consisting of dibutyltin dilaurate or dibutyltin diacetate and dibutyltin carboxylates.
The organocobalt compounds are selected from the group consisting of organic salts and/or chelates of cobalt naphthenate.

The organozinc compounds are selected from the group consisting of organic salts and/or chelates of zinc acetate, zinc acetylacetonate and zinc octoate.

The organobismuth compound is tris (neodecanoate).

The organozirconium compounds are selected from the group consisting of organic salts and/or chelates of other metals such as zirconium acetylacetonate.

The fluid medium is selected from the group consisting of selected from the group water, alcohol, ethers, esters and ketones.
The alcohols are at least one selected from the group consisting of ethanol, methanol, 1-propanol, 2-propanol (isopropanol), n-butanol, isobutanol, tert-butanol, pentanol, hexanol, ethylene glycol, and propylene glycol.
The ethers are are at least one selected from the group consisting of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, methyl t-butyl ether and ethyl t-butyl ether.
The esters are at least one selected from the group consisting of ethyl acetate and methyl acetate.
The ketones are at least one selected from the group consisting of acetone and methyl ethyl ketone.
The process for the preparation of a coating composition comprises mixing a first organic silane and a dispersing agent in a fluid medium under stirring at a temperature in the range of 25 °C to 40 °C for a first predetermined time period to obtain a first mixture. Separately an inorganic silane and a second organic silane is mixed in a first predetermined weight ratio in the fluid medium under stirring at a temperature in the range of 25 °C to 40 °C for a second predetermined time period to obtain a second mixture. The amine functional compound is added in the second mixture under stirring at a temperature in the range of 25 °C to 40 °C for a third predetermined time period to obtain a third mixture. A catalyst is mixed in the third mixture under stirring at a temperature in the range of 25 °C to 40 °C for a fourth predetermined time period to obtain a fourth mixture. The first mixture and the fourth mixture are mixed under stirring at a temperature in the range of 25 °C to 40 °C for a fifth predetermined time period in a second predetermined weight ratio to obtain the coating composition.
The first organic silane is in an amount in the range of 70 wt. % to 85 wt. % of the total amount of the organic silanes, said second organic silane is in an amount in the range of 15 wt% to 30 wt% of the total amount of the organic silanes.
The first and second organic silane is in an amount in the range of 0.25 wt% to 2 wt% with respect to the total weight of the coating composition, the inorganic silane is in an amount in the range of 0.1 wt. % to 3 wt. %, the dispersing agent is in an amount in the range of 0.1wt. % to 0.5 wt. %, the catalyst is in an amount in the range of 0.05 wt. % to 0.3 wt. %, amine functional compound is in an amount in the range of 0.1 wt. % to 0.5 wt. % and q.s. fluid medium.
The first organic silane is selected from the group consisting of monomers/oligomers of methoxy functional methyl polysiloxane, methoxy functional ethyl polysiloxane, ethoxy functional methyl polysiloxane, methoxy functional methyl phenyl polysiloxane.
The second organic silane is selected from the group consisting of monomers/oligomers of alkyl alkoxy silanes are selected from the group consisting of methyl methoxy polysiloxane, methyl trimethoxy silanes, ethyl methoxy polysiloxane, methyl ethoxy polysiloxane, methyl phenyl methoxy polysiloxane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, phenyltriethoxysilane, trialkoxyarylsilanes, dimethyldimethoxysilane and trimethylmethoxysilane; vinyl alkoxy silanes are selected from the group consisting of vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane and vinyldimethylethoxysilane;amino alkoxy silanes are selected from the group consisting of gamma-aminopropyl triethyoxysilane and gamma-aminopropyl trimethoxysilane; epoxy alkoxy silanes are selected from the group consisting of gamma- glycidoxypropyl trimethoxysilane, gamma-glycidoxypropyl triethoxysilane; mercapto alkoxy silanes are selected from the group consisting of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane and isocyanato alkoxy silanes are selected from the group consisting of gamma- isocyanopropyl triethoxysilane, gamma-isocyanopropyl trimethoxysilane or mixtures thereof.
The inorganic monomeric and oligomeric alkoxy silanes are selected from the group consisting of alkyl silicates and tetraalkoxy silanes.
The alkyl silicates are selected from the group consisting of tetraethyl orthosilicates, tetramethyl orthosilicates and their oligomers.
The tetraalkoxy silanes are selected from the group consisting of tetramethoxysilanes, tetraethoxysilanes, tetraisopropoxy silanes and tetra t-butoxy silanes.
The dispersing agent is selected from the group consisting of hydroxy functional polymer, acid functional polymer, amine functional polymer, acid and amine functional polymer and their salt.
The acid functional polymer is selected from the group consisting of phosphoric acid based polyester, acrylic acid or methacrylic acid containing acrylic polymer, acrylic acid or methacrylic acid containing styrene acrylic polymer, maleic acid grafted vinyl polymers.
The catalyst is selected from the group consisting of organic acid, organic base, organotin, organotitanium, organocobalt, organozinc, organobismuth and, organozirconium compounds.

The organic acid is selected from the group consisting of p-toluene sulphonic acid, methanesulphonic acid, acetic acid, and oxalic acid.

The organic base is selected from the group consisting of ammonia, triethylamine and monoethanolamine.

The organotitanium compounds are selected from the group consisting of titanates such as tetra (isopropyl) titanate and tetrabutyl titanate.

The organotin compounds are selected from the group consisting of dibutyltin dilaurate or dibutyltin diacetate and dibutyltin carboxylates.

The organocobalt compounds are selected from the group consisting of organic salts and/or chelates of cobalt naphthenate.

The organozinc compounds are selected from the group consisting of zinc acetate, zinc acetylacetonate and zinc octoate.

The organobismuth compound is bismuth tris (neodecanoate).

The organozirconium compounds are zirconium acetylacetonate.

The amine functional compound is selected from the group consisting of aminoalcohols, primary amines, secondary amines, tertiary amines and liquor ammonia.

The aminoalcohols are selected from the group consisting of dimethyl ethanolamine, N-methyl ethanolamine and monoethanolamine; the secondary amine is morpholine and the tertiary amine is triethylamine.

The fluid medium is selected from the group consisting of water, alcohols, ethers, esters and ketones.

The alcohols are at least one selected from the group consisting of ethanol, methanol, 1-propanol, 2-propanol (isopropanol), n-butanol, isobutanol, tert-butanol, pentanol, hexanol, ethylene glycol, and propylene glycol;
The ethers are at least one selected from the group consisting of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, methyl t-butyl ether, ethyl t-butyl ether;
The esters are at least one selected from the group consisting of ethyl acetate and methyl acetate.
The ketones are at least one selected from the group consisting of acetone and methyl ethyl ketone.
The first predetermined weight ratio is in the range of 75:1 to 99:25 and the second predetermined weight ratio is in the range of 60:25 to 75:40.
The first, fourth and fifth predetermined time period are independently in the range of 20 minutes to 40 minutes. The second predetermined time period is in the range of 2 minutes to 20 minutes and the third predetermined time period is in the range of 4 hours to 10 hours.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1 illustrates the increase in visual light transmission of the glass coated with coating composition (Example 3) of the present disclosure and blank glass.
Figure 2 illustrates the microscopic structure of the coating layer obtained by SEM.
Figure 3 illustrates refractive index of substrate with and without coating.
Figure 4 illustrates DPUR of coated glass and neat glass.
DETAILED DESCRIPTION
The present disclosure relates to a coating composition and a process for its preparation. Particularly, the present disclosure relates to an anti-reflective and anti-soiling coating for glass and solar panels.
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, known processes or well-known apparatus or 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 are 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 terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Solar energy has gained importance as a green and sustainable form of electricity generation. Solar energy is converted into electrical energy using solar panels. Dust deposition on the solar panels reduces the light transmission to the solar cell and results in reduced efficiency of the solar cell. Further, reflection of light at the glass-air interface leads to lower transmission of light to the solar cell and hence lower efficiency of the solar cell. Therefore, the cover glasses on the solar panels require an anti-reflective and anti-soiling coating.
Conventionally, in order to achieve the anti-reflective and anti-soiling properties, a low refractive index single layer coating such as coating of magnesium fluoride is applied to the glass of the solar panel. However, the conventional single layer coatings are not robust and can get damaged. Alternatively, multilayer coatings are also applied to the solar panels which involve complex deposition techniques such as vapor deposition and electrodeposition which require sophisticated and expensive equipments. Further, in order to reduce the refractive index of the coating on the glass of the solar panel, nanoparticles are externally added to make the surface of the coating rough or porous. Still further, in order to achieve anti-soiling property and low surface energy of the coating on the glass of solar panels, post treatment with fluorinated compounds such as fluorosilanes is carried out. However, additional use of nanoparticles and post treatment with fluorinated compounds is not cost effective and involves an additional step.
The present disclosure relates to an anti-reflective and anti-soiling coating for glass and solar panels.
In a first aspect, the present disclosure relates to a coating composition. The coating composition comprises 0.25 wt. % to 2 wt. % of organic silane, 0.1 wt. % to 1 wt. % of inorganic silane, 0.1 wt. % to 0.5 wt. % of a dispersing agent, 0.01 wt. % to 0.1 wt. % of a catalyst, 0.001 wt. % to 0.05 wt. % amine functional compound and q.s fluid medium wherein wt% of each ingredient is with respect to w.r.t the total weight of the coating composition. In an exemplary embodiment, the coating composition comprises 0.7 wt. % of a mixture of methoxy functional methyl polysiloxane, 0.27 wt. % of tetraethoxy silane, 0.25 wt. % of a phosphoric acid based polyester, 0.04 wt. % of p-toluene sulphonic acid, 0.006 wt. % DMEA and q.s fluid medium wherein wt% of each ingredient is with respect to the total weight of the coating composition.
The organic silane is at least one selected from the group consisting of monomers/oligomers of alkyl alkoxy silanes, vinyl alkoxy silanes, amino alkoxy silanes, epoxy alkoxy silanes, mercapto alkoxy silanes, isocyanto alkoxy silanes and their corresponding polysiloxanes. In an exemplary embodiment, the organic silane is methoxy functional methyl polysiloxane and methyl trimethoxy silane.
The alkyl alkoxy silanes are selected from the group consisting of methyl methoxy polysiloxane, methyl trimethoxy silanes, ethyl methoxy polysiloxane, methyl ethoxy polysiloxane, methyl phenyl methoxy polysiloxane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, phenyltriethoxysilane, trialkoxyarylsilanes, dimethyldimethoxysilane and trimethylmethoxysilane.
The vinyl alkoxy silanes are selected from the group consisting of vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane and vinyldimethylethoxysilane.
The amino alkoxy silanes are selected from the group consisting of gamma-aminopropyl triethyoxysilane and gamma-aminopropyl trimethoxysilane,
The epoxy alkoxy silanes are selected from the group consisting of gamma- glycidoxypropyl trimethoxysilane, gamma-glycidoxypropyl triethoxysilane.
The mercapto alkoxy silanes are selected from the group consisting of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane
The isocyanato alkoxy silanes are selected from the group consisting of gamma- isocyanopropyl triethoxysilane, gamma-isocyanopropyl trimethoxysilane or mixtures thereof. In an exemplary embodiment, the organic silanes are methoxy functional methyl polysiloxane and methyl trimethoxy silanes.
The inorganic silane is at least one selected from the group consisting of monomers/oligomers of alkyl silicates and tetraalkoxysilanes.
The alkyl silicates are selected from the group consisting of tetramethyl orthosilicates, tetraethyl orthosilicates, tetraisopropoxy orthosilicates and tetra t-butoxy orthosilicates and their oligomers. In an exemplary embodiment, the inorganic silanes are tetraethyl orthosilicates.
The tetraalkoxysilanes are selected from the group consisting of tetramethoxysilanes, tetraethoxysilanes, tetraisopropoxy silanes and tetra t-butoxy silanes.
The dispersing agent is selected from the group consisting of hydroxy functional polymer, acid functional polymer, amine functional polymer, acid and amine functional polymer and their salt.
The acid functional polymer is selected from the group consisting of phosphoric acid based polyester, acrylic acid or methacrylic acid containing acrylic polymer, acrylic acid or methacrylic acid containing styrene acrylic polymer, maleic acid grafted vinyl polymers. In an exemplary embodiment, the acid functional polymer is phosphoric acid based polyester.
The functional polymers are selected from the group consisting of polyesters, acrylics, styrene acrylics, vinyl polymers, epoxide and polyurethane polymers.
The catalyst is selected from the group consisting of organic acid, organic base, Sn, Ti, Co, Zn, Bi, Zr compounds.
The acid is selected from the group consisting of p-toluene sulphonic acid, methanesulphonic acid, acetic acid, and oxalic acid. In an exemplary embodiment, the catalyst is p-toluene sulphonic acid.
The organic base is selected from the group consisting of ammonia, triethylamine, monoethanolamine.
The titanium compounds are selected from the group consisting of titanates such as tetra (isopropyl) titanate and tetrabutyl titanate.
The organotin compounds are selected from the group consisting of dibutyltin dilaurate or dibutyltin diacetate and dibutyltin carboxylates.
The organocobalt compounds are selected from the group consisting of organic salts and/or chelates of cobalt naphthenate.
The organozinc compounds are selected from the group consisting of organic salts and/or chelates of zinc acetate, zinc acetylacetonate and zinc octoate. The organobismuth compounds are bismuth tris (neodecanoate).
The organozirconium compounds are selected from the group consisting of organic salts and/or chelates of other metals such as zirconium acetylacetonate.
The amine functional compound is selected from the group consisting of aminoalcohols, primary amines, secondary amines, tertiary amines and liquor ammonia.
The aminoalcohols are selected from the group consisting of dimethyl ethanolamine, N-methyl ethanolamine and monoethanolamine. In an exemplary embodiment, the amine functional compound is DMEA. In accordance with the present disclosure, DMEA acts as a basic catalyst for the hydrolysis and condensation reaction of the alkoxy silanes.
The primary amines are selected from the group consisting of methyl amine, ethyl amine, monoethanolamine and aniline.
The secondary amine is morpholine.
The tertiary amine is triethylamine.
The fluid medium is at least one selected from the group consisting of selected from the group consisting of water, alcohol, ethers, esters and ketones.
The alcohols are at least one selected from the group consisting of ethanol, methanol, 1-propanol, 2-propanol (isopropanol), n-butanol, isobutanol, tert-butanol, pentanol, hexanol, ethylene glycol, and propylene glycol;
The ethers are at least one selected from the group consisting of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, methyl t-butyl ether, ethyl t-butyl ether;
The esters are at least one selected from the group consisting of ethyl acetate and methyl acetate;
The ketones are at least one selected from the group consisting of acetone and methyl ethyl ketone. In an exemplary embodiment, the fluid medium is ethanol.
In accordance with the present disclosure, the coating composition of the present disclosure is applied on a substrate. The substrate is selected from the group consisting of glass, metal, plastic and ceramic.
In accordance with the present disclosure, the coating composition of the present disclosure is applied on the substrate in a single coat. In an embodiment of the present disclosure, the coating composition is configured to provide an anti-reflective coating with an increase in light transmission of 1 to 4% when coated on one side of the substrate.
A solid content of the coating composition of the present disclosure is in the range of 0.5% to 10%.
The coating composition of the present disclosure can be applied by using conventional techniques. The conventional techniques are selected from the group consisting of spray coating, brush coating, dip coating and curtain coating.
The coating composition of the present disclosure when applied on the substrate has a dry film thickness (DFT) in the range of 50 nm to 300 nm. Preferably, the coating composition of the present disclosure has a dry film thickness (DFT) in the range of 100 nm to 200 nm.
In another aspect, the present disclosure provides a process for the preparation of a coating composition.
The process for the preparation of coating composition of the present disclosure is simple and economic.
The process for the preparation of a coating composition comprises the following steps:
a. mixing a first organic silane and a dispersing agent in a fluid medium under stirring at a temperature in the range of 25 °C to 40 °C for a first predetermined time period to obtain a first mixture;
b. separately mixing an inorganic silane and a second organic silane in a first predetermined weight ratio in the fluid medium under stirring at a temperature in the range of 25 °C to 40 °C for a second predetermined time period to obtain a second mixture;
c. adding amine functional compound in the second mixture under stirring at a temperature in the range of 25 °C to 40 °C for a third predetermined time period to obtain a third mixture;
d. mixing a catalyst in the third mixture under stirring at a temperature in the range of 25 °C to 40 °C for a fourth predetermined time period to obtain a fourth mixture; and
e. mixing the first mixture and the fourth mixture under stirring at a temperature in the range of 25 °C to 40 °C for a fifth predetermined time period in a second predetermined weight ratio to obtain the coating composition.
The process is described in detail herein below:
In a first step, a first organic silane and a dispersing agent is mixed in a fluid medium under stirring at a temperature in the range of 25 °C to 40 °C for a first predetermined time period to obtain a first mixture.
The first organic silane is selected from the group consisting of monomers/oligomers of methoxy functional methyl polysiloxane, methoxy functional ethyl polysiloxane, ethoxy functional methyl polysiloxane, methoxy functional methyl phenyl polysiloxane.
The second organic silane is selected from the group consisting of methyl methoxy polysiloxane, methyl trimethoxy silanes, ethyl methoxy polysiloxane, methyl ethoxy polysiloxane, methyl phenyl methoxy polysiloxane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, phenyltriethoxysilane, trialkoxyarylsilanes, dimethyldimethoxysilane and trimethylmethoxysilane; vinyl alkoxy silanes are selected from the group consisting of vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane and vinyldimethylethoxysilane. Amino alkoxy silanes are selected from the group consisting of gamma-aminopropyl triethyoxysilane and gamma-aminopropyl trimethoxysilane; epoxy alkoxy silanes are selected from the group consisting of gamma- glycidoxypropyl trimethoxysilane, gamma-glycidoxypropyl triethoxysilane; mercapto alkoxy silanes are selected from the group consisting of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane and isocyanato alkoxy silanes are selected from the group consisting of gamma- isocyanopropyl triethoxysilane, gamma-isocyanopropyl trimethoxysilane or mixtures thereof. In an exemplary embodiment, the first organic silane is methoxy functional methyl polysiloxane.
The dispersing agent is selected from the group consisting of hydroxy functional polymer, acid functional polymer, amine functional polymer, acid and amine functional polymer and their salt. The acid functional polymer is selected from the group consisting of phosphoric acid based polyester, acrylic acid or methacrylic acid containing acrylic polymer, acrylic acid or methacrylic acid containing styrene acrylic polymer, maleic acid grafted vinyl polymers. In an exemplary embodiment, the dispersing agent is phosphoric acid based polyester.
The fluid medium is selected from the group consisting of water, alcohols, ethers, esters and ketones. The alcohols are at least one selected from the group consisting of ethanol, methanol, 1-propanol, 2-propanol (isopropanol), n-butanol, isobutanol, tert-butanol, pentanol, hexanol, ethylene glycol, and propylene glycol.
The ethers are at least one selected from the group consisting of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, methyl t-butyl ether and ethyl t-butyl ether.
The esters are at least one selected from the group consisting of ethyl acetate and methyl acetate.
The ketones are at least one selected from the group consisting of acetone and methyl ethyl ketone.
The first predetermined time period is in the range of 20 minutes to 40 minutes. In an exemplary embodiment, the first predetermined time period is 30 minutes.
The first organic silane is in an amount in the range of 70 wt. % to 85 wt. % of the total amount of the organic silanes. In an exemplary embodiment, the first organic silane is 77 wt% of the total weight of the organic silanes.
In a second step, an inorganic silane and a second organic silane are mixed separately in a first predetermined weight ratio in the fluid medium under stirring at a temperature in the range of 25 °C to 40 °C for a second predetermined time period to obtain a second mixture.
The inorganic monomeric and oligomeric alkoxy silanes are selected from the group consisting of monomers/oligomers of alkyl silicates and tetraalkoxysilanes. The alkyl silicates are selected from the group consisting of tetraethyl orthosilicates, tetramethyl orthosilicates and their oligomers. The tetraalkoxysilanes are selected from the group consisting of tetramethoxysilanes, tetraethoxysilanes, tetraisopropoxy silanes and tetra t-butoxy silanes. In an exemplary embodiment, the alkyl silicates are tetraethyl orthosilicates.
The second organic silane is selected from the group consisting methyl methoxy polysiloxane, methyl trimethoxy silanes, ethyl methoxy polysiloxane, methyl ethoxy polysiloxane, methyl phenyl methoxy polysiloxane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, phenyltriethoxysilane, trialkoxyarylsilanes, dimethyldimethoxysilane and trimethylmethoxysilane; vinyl alkoxy silanes are selected from the group consisting of vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane and vinyldimethylethoxysilane;amino alkoxy silanes are selected from the group consisting of gamma-aminopropyl triethyoxysilane and gamma-aminopropyl trimethoxysilane; epoxy alkoxy silanes are selected from the group consisting of gamma- glycidoxypropyl trimethoxysilane, gamma-glycidoxypropyl triethoxysilane; mercapto alkoxy silanes are selected from the group consisting of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane and isocyanato alkoxy silanes are selected from the group consisting of gamma- isocyanopropyl triethoxysilane, gamma-isocyanopropyl trimethoxysilane or mixtures thereof. In an exemplary embodiment, the second organic silane is methyl trimethoxy silane.
The second organic silane is in an amount in the range of 15 wt. % to 30 wt. % of the total amount of the organic silanes. In an exemplary embodiment, the second organic silane is 22 wt% of the total weight of the organic silanes.
The first predetermined weight ratio of inorganic silane and a second organic silane is in the range of 75:1 to 99:25. In an exemplary embodiment, the first predetermined weight ratio of inorganic silane and a second organic silane is 98:2.
The second predetermined time period is in the range of 2 minutes to 20 minutes. In an exemplary embodiment, the second predetermined time period is 10 minutes.
In a third step, amine functional compound is added in the second mixture under stirring at a temperature in the range of 25 °C to 40 °C for a third predetermined time period to obtain a third mixture.
The third predetermined time period is in the range of 4 hours to 10 hours. In an exemplary embodiment, the third predetermined time period is 6 hours.
In a fourth step, a catalyst is mixed in the third mixture under stirring at a temperature in the range of 25 °C to 40 °C for a fourth predetermined time period to obtain a fourth mixture.
The first and second organic silane are in an amount in the range of 0.25 wt% to 2 wt% with respect to the total weight of the coating composition, said inorganic silane is in an amount in the range of 0.1 wt. % to 1 wt. % with respect to the total weight of the coating composition, said dispersing agent is in an amount in the range of 0.1 wt. % to 0.5 wt. % with respect to the total weight of the coating composition, said catalyst is in an amount in the range of 0.01 wt. % to 0.1 wt. % with respect to the total weight of the coating composition, amine functional compound is in an amount in the range of 0.001 wt. % to 0.05 wt. % with respect to the total weight of the coating composition and q.s. fluid medium.
The catalyst is selected from the group consisting of organic acid, organic base, organotin, organotitanium, organocobalt, organozinc, organobismuth and, organozirconium compounds.
The acid is selected from the group consisting of p-toluene sulphonic acid, methane sulphonic acid, acetic acid, and oxalic acid. In an exemplary embodiment, the catalyst is p-toluene sulphonic acid.
The organic base is selected from the group consisting of ammonia, triethylamine and monoethanolamine.
The organotitanium compounds are selected from the group consisting of titanates such as tetra (isopropyl) titanate and tetrabutyl titanate.
The organotin compound selected from the group consisting of dibutyltin dilaurate or dibutyltin diacetate and dibutyltin carboxylates.
The organocobalt compounds selected from the group consisting of organic salts and/or chelates of cobalt naphthenate.
The organozinc compounds selected from the group consisting of organic salts and/or chelates of zinc acetate, zinc acetylacetonate and zinc octoate.
The organobismuth compounds are bismuth tris (neodecanoate).
The organozirconium compounds selected from the group consisting of organic salts and/or chelates of other metals such as zirconium acetylacetonate.
The fourth predetermined time period is independently in the range of 20 minutes to 40 minutes. In an exemplary embodiment, the fourth predetermined time period is 30 minutes.
In a fifth step, the first mixture and the fourth mixture are mixed under stirring at a temperature in the range of 25 °C to 40 °C for a fifth predetermined time period in a second predetermined weight ratio to obtain the coating composition.
The fifth predetermined time period is in the range of 20 minutes to 40 minutes. In an exemplary embodiment, the fifth predetermined time period is 30 minutes.
The second predetermined weight ratio of the first mixture to the fourth mixture is in the range of 60:25 to 75:40. In an exemplary embodiment, the second predetermined weight ratio of the first mixture to the fourth mixture is 70:30.
The coating composition is applied on glass substrate and baked at a temperature in the range of 400 °C to 800 °C for a time period in the range of 10 seconds to 5 minutes to attain the desired film.
The foregoing description of the embodiments has been provided for purposes of illustration and 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.
EXPERIMENTAL DETAILS:
Experiment 1: Process for the preparation of the coating composition:
Example 1:
Preparation of Part-A
In a 100 ml round bottom flask equipped with stirrer, 96.05 ml ethyl alcohol, 0.7g of methoxy functional methyl polysiloxane and 0.25g of phosphoric acid-based polyester (dispersing agent) were added and stirred at room temperature for 30 minutes to obtain 97 g of first mixture.
Preparation of Part-B
In a 100 ml glass reactor, equipped with stirrer, 78.28 ml of ethyl alcohol was charged followed by gradual addition of 9.8 g of tetraethyl orthosilicate monomer and 0.2g of MTMS (Methyl trimethoxy silane) over 10 minutes. The mixture was stirred for 10 minutes to obtain a second mixture. 0.2g of DMEA (N,N-Dimethyl ethanolamine) is added to the second mixture and stirred at a temperature of 30 °C for six hours to obtain a third mixture. p-toluene sulphonic acid solution (1.28 g of PTSA dissolved in 10.24 ml of DM water) was added to the third mixture and stirred for 30 minutes at 30 °C to obtain a 100 g of fourth mixture.
Preparation of coating composition
7 g of Part-A and 3 g of Part-B were mixed at 30 °C and stirred for 30 minutes to obtain the 10 g of coating composition.
The coating composition was prepared in a similar manner as in example 1 by varying the amounts of tetraethoxy silane and methyl trimethoxy silane. The amounts are tabulated in table 1 below:
Coating composition prepared in accordance with the present disclosure Comparative examples
Example no. 1 2 3 4 5 6 7 8 9 10 11 12 13
Part-A
methoxy functional methyl polysiloxane 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.5 0.3 0.2
Dispersing agent (Phosphoric acid based polyester) 0.25 0 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25
Ethyl alcohol 96.05 96.05 96.05 96.05 96.05 96.05 96.05 96.05 96.05 96.05 94.25 92.45 91.55
Part-B
Tetraethoxysilane 9.8 9 9 8 7 6 5 2 3 1 8.8 8.8 8.8
Methyl trimethoxysilane 0.2 1 1 2 3 4 5 8 7 9 1.2 1.2 1.2
Tetraethoxy silane 9.8 9 9 8 7 6 5 2 3 1 8.8 8.8 8.8
Ethyl alcohol 78.28 78.28 78.28 78.28 78.28 78.28 78.28 78.28 78.28 78.28 78.28 78.28 78.28
N,N-Dimethyl aminoethanol 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2
p-toluenesulfonic acid 1.28 1.28 1.28 1.28 1.28 1.28 1.28 1.28 1.28 1.28 1.28 1.28 1.28
DM Water 10.24 10.24 10.24 10.24 10.24 10.24 10.24 10.24 10.24 10.24 10.24 10.24 10.24
Ratio of tetra/trifunctional silane (Tetraethoxysilane/Methyl trimethoxysilane) 98/2 90/10 90/10 80/20 70/30 60/40 50/50 20/80 30/70 10/90 90/10 90/10 90/10
Ratio of A/B 70/30 70/30 70/30 70/30 70/30 70/30 70/30 70/30 70/30 70/30 50/50 30/70 20/80
Increase in visual light transmission 0.75 1.8 2.5 0.7 NA NA NA NA NA NA 0.2 0.1 0.1

NA: No increase in light transmission
From the above table, it can be inferred that only for specific ratios of tetra to trifunctional silanes and specific ratio of part A to part B, enhanced light transmission is obtained as shown in examples 1 to 4. Further it can be seen from examples 2 and 3 that in presence of dispersing agent, there is a further enhancement of visual light transmission. The comparative examples 5 to 13 show negligible increase in light transmission.
Experiment 2: Coating of the coating composition on the substrate prepared in accordance with the present disclosure
The application of the coating composition prepared in accordance with the present disclosure was done by three different types of tools i.e. bar coater, ragging and spray coating. The mixture of A and B was applied by bar coater on 5 x 3 inch glass panels and baked at 700 deg C for 100 seconds in a muffle furnace. The coated glass was tested for visual light transmission. The results are given in table 1 above.
Figure 1 illustrates the increase in visual light transmission of the glass coated with coating composition (Example 3) of the present disclosure and blank glass. From figure 1 it was seen that the increase in visual light transmission is 2.5 units at 550nm as compared to the blank glass.
Experiment 3: Study of morphology of the coating composition
Figure 2 illustrates the microscopic structure (by SEM) of the coating layer (anti-reflective (AR) coating film) prepared by using the coating composition of the present disclosure.
From figure 2-A, it was seen that, at 250 oC baking temperature, the surface morphology of anti-reflective (AR) coating film showed wrinkling. From figure 2-B wherein the baking temperature of the film was 700 oC, and 1% solids without dispersing agent is used in the coating composition, agglomeration of particles was observed. From figure 2-C it was observed that by using1% solids and a dispersing agent, the anti-reflective (AR) coating film prepared by coating composition, it was observed that the particles were uniformly distributed.
From the cross-sectional images of AR coating film, three different DFT i.e. 0.25 %, 1% and 3% NMV respectively were calculated. Ideally, for AR coating film the DFT should be 100 to 150 nm to give better light scattering with enhancing the visual light transmission. It was observed that a) at 0.25 % solids the AR coating DFT is very less i.e. 75 to 80 nm, b) at 1 % solid DFT is 147 to 170 nm. c) at 3 % solids the DFT is 277 to 330 nm.
It was observed that the visual light transmission was better in 1 % solids and RI also decreases. Due to the high DFT, light scattering was less and decrease in the visual light transmission was observed.
Table 2 below illustrates the effect of application solids and DFT to visual light transmission.
Application Solids Coating DFT (nm) Light transmission increase at 550 nm
5% NA 0.26%
3% ~300 nm 0.85%
1% with/ without dispersing agent 100-150 nm 2.5%/1.8%
0.75% 100-150 nm 2.07%
0.25% ~50-100 nm 0.39%
5% NA 0.26%

Experiment 4: Comparison of the refractive index of silicon substrate with and without coating
Figure 3 illustrates the refractive index of silicon substrate with and without coating. From figure 3 it was seen that decrease in RI (refractive index) of the coating enables the increase in light transmission. RI of coated substrate was 1.31 compared to 1.76 for the uncoated substrate.
Experiment 5: Surface energy and contact angle
Table 3 illustrates surface energy of the coated substrate was reduced to 37 mN/m and 49 mN/m as compared to 65 mN/m for the neat cover glass, hence less dust adheres on the coated substrate.
Table- 3: - Surface energy of blank and coated solar panel
Sr.No. Name Water contact angle (°) Diiodomethane
(°) Surface free energy (Mn/m) Disperse Polar
1 Blank glass panel 32 33 65.02 32.74 32.28
2 ARC at 1% solids 61 33 49.73 36.7 13.03
3 ARC at 1% solids+dispersing agent 85 50 37.07 34.14 2.12

Experiment 6: DPUR test
DPUR test was done with carbon black. Carbon black was spread over the coated and uncoated glass and rubbed with tissue paper for 10 cycles. The coated glass shows less deposition of carbon than blank glass as shown in figure 4. Same test was done with natural dust, wherein dust deposition was less on the coated glass than on the blank glass.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of;
- a coating composition that
• can be applied as a single coat ;
• has anti-reflective and anti-soiling property;
• does not require external addition of nanoparticles;
• does not require post-treatment with fluorinated compounds on the coating film;
• is abrasion resistant;
• is stable; and
- a process for preparing the coating composition is simple and economic.
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 embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
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 disclosure to achieve one or more of the desired object or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments 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. ,CLAIMS:WE CLAIM:
1. A coating composition comprising a reaction product of:
a. 0.25 wt. % to 2 wt. % of organic silane;
b. 0.1 wt. % to 1 wt. % of inorganic silane;
c. 0.1 wt. % to 0.5 wt. % of a dispersing agent;
d. 0.01 wt. % to 0.1 wt. % of a catalyst;
e. 0.001 wt. % to 0.05 wt. % amine functional compound; and
f. q.s fluid medium;
wherein wt% of each ingredient is with respect to the total weight of the coating composition.

2. The coating composition as claimed in claim 1, wherein said organic silane is at least one selected from the group consisting of monomers/oligomers of alkyl alkoxy silanes, vinyl alkoxy silanes, amino alkoxy silanes, epoxy alkoxy silanes, mercapto alkoxy silanes, isocyanto alkoxy silanes and their corresponding polysiloxanes.

3. The coating composition as claimed in claim 2, wherein
• said alkyl alkoxy silanes are selected from the group consisting of methyl methoxy polysiloxane, methyl trimethoxy silanes,ethyl methoxy polysiloxane, methyl ethoxy polysiloxane, methyl phenyl methoxy polysiloxane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, phenyltriethoxysilane, trialkoxyarylsilanes, dimethyldimethoxysilane and trimethylmethoxysilane;
• said vinyl alkoxy silanes are selected from the group consisting of vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane and vinyldimethylethoxysilane;
• said amino alkoxy silanes are selected from the group consisting of gamma-aminopropyl triethoxysilane and gamma-aminopropyl trimethoxysilane;
• said epoxy alkoxy silanes are selected from the group consisting of gamma-glycidoxypropyl trimethoxysilane and gamma-glycidoxypropyl triethoxysilane;
• said mercapto alkoxy silanes are selected from the group consisting of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; and
• said isocyanato alkoxy silanes are selected from the group consisting of gamma-isocyanopropyl triethoxysilane, gamma-isocyanopropyl trimethoxysilane or mixtures thereof.

4. The coating composition as claimed in claim 1, wherein said inorganic silane is at least one selected from the group consisting of monomers/oligomers of alkyl silicates and tetraalkoxysilanes.

5. The coating composition as claimed in claim 4, wherein said alkyl silicates are selected from the group consisting of tetraethyl orthosilicates, tetramethyl orthosilicates and their oligomers and wherein said tetraalkoxysilanes are selected from the group consisting of tetramethoxysilanes, tetraethoxysilanes, tetraisopropoxy silanes and tetra t-butoxy silanes.

6. The coating composition as claimed in claim 1, wherein said dispersing agent is selected from the group consisting of hydroxy functional polymer, acid functional polymer, amine functional polymer, acid and amine functional polymer and their salt.

7. The coating composition as claimed in claim 6, wherein said acid functional polymer is selected from the group consisting of phosphoric acid based polyester, acrylic or methacrylic acid containing acrylic polymer, acrylic or methacrylic acid containing styrene acrylic polymer, and maleic acid grafted vinyl polymers.

8. The coating composition as claimed in claim 1, wherein said catalyst is selected from the group consisting of organic acid, organic base, organotin, organotitanium, organ cobalt, organo zinc, organobismuth and organozirconium compounds.

9. The coating composition as claimed in claim 8, wherein
• said organic acid is selected from the group consisting of p-toluene sulphonic acid, methane sulphonic acid, acetic acid and oxalic acid;
• said organic base is selected from the group consisting of ammonia, triethylamine, monoethanolamine; and
• said organotitanium compounds are selected from the group consisting of titanates such as tetra(isopropyl) titanate and tetrabutyl titanate;
• said organotin compounds are selected from the group consisting of dibutyltin dilaurate, dibutyltin diacetate and dibutyltin carboxylates;
• said organocobalt compounds are selected from the group consisting of organic salts and/or chelates of cobalt naphthenate;
• said organozinc compounds are selected from the group consisting of organic salts and/or chelates of zinc acetate, zinc acetylacetonate and zinc octoate;
• said organobismuth compound is bismuth tris(neodecanoate); and
• said organozirconium compound is zirconium acetylacetonate.

10. The coating composition as claimed in claim 1, wherein said fluid medium is selected from the group consisting of water, alcohol, ethers, esters and ketones.

11. The coating composition as claimed in claim 10, wherein
• said alcohols are at least one selected from the group consisting of ethanol, methanol, 1-propanol, 2-propanol (isopropanol), n-butanol, isobutanol, tert-butanol, pentanol, hexanol, ethylene glycol, and propylene glycol;
• said ethers are at least one selected from the group consisting of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, methyl t-butyl ether and ethyl t-butyl ether;
• said esters are at least one selected from the group consisting of ethyl acetate and methyl acetate; and
• said ketones are at least one selected from the group consisting of acetone and methyl ethyl ketone.

12. The coating composition as claimed in claim 1, wherein said amine functional compound is selected from the group consisting of amino alcohols, primary amines, secondary amines, tertiary amines and liquor ammonia; wherein said amino alcohols are selected from the group consisting of dimethyl ethanolamine, N-methyl ethanolamine and monoethanolamine; said primary amines are selected from the group consisting of methyl amine, ethyl amine, monoethanolamine and aniline; said secondary amine is morpholine; and said tertiary amine is triethylamine.

13. A process for the preparation of a coating composition, said process comprising the following steps:

a. mixing a first organic silane and a dispersing agent in a fluid medium under stirring at a temperature in the range of 25 °C to 40 °C for a first predetermined time period to obtain a first mixture;
b. separately mixing an inorganic silane and a second organic silane in a first predetermined weight ratio in said fluid medium under stirring at a temperature in the range of 25 °C to 40 °C for a second predetermined time period to obtain a second mixture;
c. adding amine functional compound in said second mixture under stirring at a temperature in the range of 25 °C to 40 °C for a third predetermined time period to obtain a third mixture;
d. mixing a catalyst in said third mixture under stirring at a temperature in the range of 25 °C to 40 °C for a fourth predetermined time period to obtain a fourth mixture; and
e. mixing said first mixture and said fourth mixture under stirring at a temperature in the range of 25 °C to 40 °C for a fifth predetermined time period in a second predetermined weight ratio to obtain said coating composition.

14. The process as claimed in claim 13, wherein said first organic silane is in an amount in the range of 70 wt. % to 98 wt. % of the total amount of the organic silanes, said second organic silane is in an amount in the range of 2 wt% to 30 wt% of the total amount of the organic silanes.

15. The process as claimed in claim 13, wherein said first and second organic silane are in an amount in the range of 0.25 wt% to 2 wt% with respect to the total weight of the coating composition, said inorganic silane is in an amount in the range of 0.1 wt. % to 1 wt. % with respect to the total weight of the coating composition, said dispersing agent is in an amount in the range of 0.1 wt. % to 0.5 wt. % with respect to the total weight of the coating composition, said catalyst is in an amount in the range of 0.01 wt. % to 0.1 wt. % with respect to the total weight of the coating composition, amine functional compound is in an amount in the range of 0.001 wt. % to 0.05 wt. % with respect to the total weight of the coating composition and q.s. fluid medium.

16. The process as claimed in claim 13, wherein said first organic silane is selected from the group consisting of monomers/oligomers of methoxy functional methyl polysiloxane, methoxy functional ethyl polysiloxane, ethoxy functional methyl polysiloxane, methoxy functional methyl phenyl polysiloxane; and second organic silane is selected from the group consisting of methyl methoxy polysiloxane, methyl trimethoxy silanes, ethyl methoxy polysiloxane, methyl ethoxy polysiloxane, methyl phenyl methoxy polysiloxane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, n-octyltriethoxysilane, phenyltriethoxysilane, trialkoxyarylsilanes, dimethyldimethoxysilane and trimethylmethoxysilane; vinyl alkoxy silanes selected from the group consisting of vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane and vinyldimethylethoxysilane;amino alkoxy silanes selected from the group consisting of gamma-aminopropyl triethyoxysilane and gamma-aminopropyl trimethoxysilane; epoxy alkoxy silanes selected from the group consisting of gamma- glycidoxypropyl trimethoxysilane, gamma-glycidoxypropyl triethoxysilane; mercapto alkoxy silanes selected from the group consisting of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane and isocyanato alkoxy silanes selected from the group consisting of gamma- isocyanopropyl triethoxysilane, gamma-isocyanopropyl trimethoxysilane or mixtures thereof.

17. The process as claimed in claim 13, wherein said inorganic monomeric and oligomeric alkoxy silanes are selected from the group consisting of monomers/oligomers of alkyl silicates and tetraalkoxysilanes.

18. The process as claimed in claim 17, wherein said alkyl silicates are selected from the group consisting of tetraethyl orthosilicates, tetramethyl orthosilicates and their oligomers; and wherein said tetraalkoxysilanes are selected from the group consisting of tetramethoxysilanes, tetraethoxysilanes, tetraisopropoxy silanes and tetra t-butoxy silanes.

19. The process as claimed in claim 13, wherein said dispersing agent is selected from the group consisting of hydroxy functional polymer, acid functional polymer, amine functional polymer, acid and amine functional polymer and their salt.

20. The process as claimed in claim 19, wherein said acid functional polymer is selected from the group consisting of phosphoric acid based polyester, acrylic acid or methacrylic acid containing acrylic polymer, acrylic acid or methacrylic acid containing styrene acrylic polymer, and maleic acid grafted vinyl polymers.

21. The process as claimed in claim 13, wherein said catalyst is selected from the group consisting of organic acid, organic base, organotin, organotitanium, organocobalt, organozinc, organobismuth and , organozirconiumcompounds.

22. The process as claimed in claim 21, wherein
• said organic acid is selected from the group consisting of p-toluene sulphonic acid, methanesulphonic acid, acetic acid and oxalic acid;
• said organic base is selected from the group consisting of ammonia, triethylamine and monoethanolamine;
• said organotitanium compounds are selected from the group consisting of titanates such as tetra(isopropyl) titanate and tetrabutyl titanate;
• said organotin compounds are selected from the group consisting of dibutyltin dilaurate, dibutyltin diacetate and dibutyltin carboxylates;
• said organocobalt compounds are selected from the group consisting of organic salts and/or chelates of cobalt naphthenate;
• said organozinc compounds are selected from the group consisting of organic salts and/or chelates of zinc acetate, zinc acetylacetonate and zinc octoate;
• said organobismuth compound is bismuth tris(neodecanoate);
• said organozirconium compound is zirconium acetylacetonate.

23. The process as claimed in claim 13, wherein said fluid medium is selected from the group consisting of water, alcohols, ethers, esters and ketones.

24. The process as claimed in claim 23, wherein
• said alcohols are at least one selected from the group consisting of ethanol, methanol, 1-propanol, 2-propanol (isopropanol), n-butanol, isobutanol, tert-butanol, pentanol, hexanol, ethylene glycol, and propylene glycol;
• said ethers are at least one selected from the group consisting of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, methyl t-butyl ether and ethyl t-butyl ether;
• said esters are at least one selected from the group consisting of ethyl acetate and methyl acetate;
• said ketones are at least one selected from the group consisting of acetone, methyl ethyl ketone.

25. The process as claimed in claim 13, wherein said amine functional compound is selected from the group consisting of amino alcohols, primary amines, secondary amines, tertiary amines and liquor ammonia; wherein said amino alcohols are selected from the group consisting of dimethyl ethanolamine, N-methyl ethanolamine and monoethanolamine; said primary amines are selected from the group consisting of methyl amine, ethyl amine, monoethanol amine and aniline; and said secondary amine is morpholine and said tertiary amine is triethylamine.

26. The process as claimed in claim 13, wherein said first predetermined weight ratio is in the range of 75:1 to 99:25 and said second predetermined weight ratio is in the range of 60:25 to 75:40.

27. The process as claimed in claim 13, wherein
• said first, fourth and fifth predetermined time period are independently in the range of 20 minutes to 40 minutes;
• said second predetermined time period is in the range of 2 minutes to 20 minutes; and
• said third predetermined time period is in the range of 4 hours to 10 hours.

Dated this 29th day of March, 2024

_______________________________
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