FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFIC A TION
(See section 10, rule 13)
/. Title of the invention
A METHOD FOR PREPARING A COATING COMPOSITION AND COATING COMPOSITION THEREOF
2. Applicant(s)
Name Nationality Address
rATA CHEMICALS LIMITED INDIA BOMBAY HOUSE, 24 HOMI MODI STREET, MUMBAI -
400001
3. Preamble to the description
COMPLETE SPECIFIC A TION
The following specification particularly describes the invention and the manner in which it is
to be performed.

The disclosure generally relates to a coating composition for a substrate and a method for preparing the coating composition. More particularly the disclosure relates to a coating composition comprising of functionalized silica nanoparticles in organic matrix and method for preparing the same.
DESCRIPTION OF RELATED ART
Polymeric materials are one of the most important industrial products in use today. Inorganic-organic composite materials as nanocomposites gained increased attention of researchers in the past few years especially for coating applications. It is well known in prior art that the mechanical properties of polymer based coating compositions can be improved by addition of inorganic fillers. These inorganic fillers of different metal oxides can be dispersed in the polymer matrix. Moreover, the use of metal particles or metal oxides in nano scale is promising as it allows tuning the properties of polymers as well as organic coating materials by controlling the degree of interaction between the organic and inorganic matrix.
The use of low molecular weight reactive solvents as processing aid and dispersing agent for dispersion of nanosize fumed silica particles in polyethersulphone (PES) matrix has also been reported in literature as melt mixing of nanoparticles with high performance polymers is not feasible due to severe shear heating and formation of particle aggregates. (Sadhan C. Jana and Sachin Jain (2001), "Dispersion of nanofillers in high performance polymers using reactive solvents as processing aids" Polymer, Volume 42, Issue 16, July 2001, Pages 6897-6905)
Furthermore, United States Patent Application No. 2003/0027917 discloses an acrylic urethane paint composition with nano silica dispersion used as antiscratch coating. The nano silica particles dispersed in the organic matrix has a particle size from 5 to 300

nanometer and hydrophilic silica nano particles are treated with silane compound to make silica nano particles hydrophobic.
One of the biggest restraint in developing a transparent coating composition is to disperse nano material in the organic matrix in a homogeneous manner thereby avoiding any macroscopic separation. Dispersing of nano particles especially, silica nano particles to transparent coating composition based on epoxy or polyurethane resins often lead to the problem of aggregation and dispersion issues and moreover the coating cannot retain transparency.
Thus there is a need for effective measures for development of coating composition which will retain transparency after dispersion of nanoparticles in an organic matrix. Moreover, the desired coating should possess improved properties such as mechanical properties, antiscratch properties, abrasion resistance, heat stability etc.
SUMMARY
A method for preparing a coating composition is disclosed. The method includes preparing a diol functionalized metal nanoparticles by reacting a metal precursor with an epoxy based silane in presence of hydrochloric acid. The method further includes adding the diol functionalized metal nanoparticles and a crosslinker to an organic polymer, the crosslinker capable of forming a covalent bond with the diol and forming a covalent bond with the organic polymer.
In accordance with an aspect, a coating composition is also disclosed. The coating composition includes diol finctionalised metal nanoparticles, an organic polymer and a crosslinker wherein the crosslinker forms a covalent bond with diol functionalized metal nanoparticles and the organic polymer.

DETAILED DESCRIPTION
To promote an understanding of the principles of the invention, reference will be made to the embodiment illustrated in the drawing and specific language will be used to describe the same. It will nevertheless be understood that no limitation of scope of the invention is thereby intended, such alterations and further modifications in the described method and such further applications of the principles of the inventions as illustrated therein being contemplated as would normally occur to one skilled in art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
The present disclosure provides a method for preparing a coating composition. The method comprises of obtaining a sol of a diol functionalized metal nanoparticles by reacting a metal precursor with an epoxy based silane in presence of hydrochloric acid, water, an alcohol and optionally a chlorosilane compound or an aluminium based compound. The method further comprises of adding the diol functionalized metal nanoparticles and a crosslinker to an organic polymer wherein the crosslinker is capable of forming a covalent bond with the diol and forming a covalent bond with the organic polymer.
In accordance with an aspect, the metal precursor is mixed with epoxy based silane and may be followed by stirring for a time period in the range of 1 -15 minutes to obtain a reaction mixture. By way of specific example, the metal precursor is mixed with epoxy based silane followed by stirring for a time period of 5 minutes to obtain a reaction mixture.

In accordance with an aspect, a mixture of hydrochloric acid, water and alcohol is added to the reaction medium and may be followed by stirring for a time period in the range of 30 minutes-2 hours. By way of specific example, a mixture of hydrochloric acid, water and alcohol is added to the reaction medium followed by stirring for a time period of 1 hour.
In accordance with an aspect, the method further comprises adding methanol to the mixture of metal precursor, epoxy based silane, hydrochloric acid, water and alcohol and may be refluxed for a time period in the range of 1-3 hours at a temperature in the range of 80-100°C to obtain a functionalized sol of metal nanoparticles. By way of specific example, the refluxing is performed for a time period of 2 hours at a temperature of 90°C to obtain functionalized sol of metal nanoparticles.
In accordance with an aspect, a solvent may be added to the functionalized sol of metal nanoparticles followed by the removal of solvents by placing the same on rotavapour or subjecting the same to distillation. In accordance with an embodiment, the distillation may be performed at a temperature in the range of 110-130°C for the removal of non polar solvents. By way of specific example, the distillation temperature is 117°C for the removal of solvents.
In accordance with an embodiment the solvents are ethanol, butanol, toluene, butyl acetate or combination thereof.
In accordance with an embodiment, final nanoparticle dispersion obtained is in the range of 15-35 weight percent.
In accordance with an embodiment, the metal precursor used is tetraethylorthosilicate (TEOS).

In accordance with an aspect, the diol functionalized metal nanoparticles are silica nanoparticles functionalized with an epoxy based silane.
In accordance with an embodiment, epoxy based silane is glycidoxy propyl trimethoxy silane.
In accordance with an embodiment, the alcohol is butanol.
In accordance with an embodiment, the chlorosilane compound is chloro trimethyl silane.
In accordance with an embodiment, the aluminium based compound is aluminium acetylacetonate.
In accordance with an aspect, the organic polymer is polyacrylate-ol, polyester-ol or epoxy resin. By way of specific example, epoxy resin can be aliphatic, aromatic, cycloaliphatic or heterocyclic. Furthermore, epoxy resins can be selected from the compounds produced by addition polymerization of epoxy containing functional monomers selected from glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether in conjunction to unsaturated monomers based on styrene, methyl styrene, ethyl styrene, vinyl toluene, acrylamide,methacrylamide, acrylonitrile and its derivatives, methyl methacrylate, isopropylmethacrylate and isobutyl methacrylate.
In accordance with an aspect, the crosslinker is selected from polyisocyanate, polyamide or their equivalents.
The present disclosure also provides a coating composition. Particularly, a coating composition having a true chemical bond between an inorganic and an organic matrix is disclosed. The coating composition comprises of diol finctionalised metal nanoparticles, an organic polymer and a crosslinker wherein the crosslinker forms a covalent bond with diol functionalized metal nanoparticles and the organic polymer.

In accordance with an aspect, the diol functionalized metal nanoparticles are silica nanoparticles functionalized with an epoxy based silane.
In accordance with an embodiment, epoxy based silane is glycidoxy propyl trimethoxy silane.
In accordance with an aspect, the organic polymer is polyacrylate-ol, polyester-ol or epoxy resin.
In accordance with an aspect, the crosslinker is selected from polyisocyanate, polyamide and their equivalents.
The present disclosure also relates to a method of providing a coating composition on a substrate. The method comprises of drawing a film of the coating composition on the substrate with the help of an applicator.
In accordance with an aspect, the thickness of the film is in the range of 10-40 micron. By way of specific example, the applicator is used to form a 25 micron thick film of coating on a glass plate.
The method further comprises of flashing the film in open air preferably for time period in the range of 2-8 minutes followed by curing the film at a temperature in the range of 110-140°C for time period in the range of 10-40 minutes. Thus, a transparent and a hard coating with pencil hardness in the range of 2H-4H is obtained. By way of specific example, the flashing of film in open air is for the time period of 5 minutes followed by curing of film at a temperature of 120°C for the time period of 30 minutes.
The following examples of preparing a coating composition and a coating thereof are exemplary and should not be understood to be in any way limiting. Example 1 About 5.415 grams of TEOS(Aldrich) and 2.5 milliliter of glycidoxy propyl trimethoxy

silane (GLYMO, Aldrich) are taken in 50 ml single neck round bottomed flask. This mixture is stirred for 5 minutes to obtain a reaction medium. To this reaction medium, a mixture of HC1, water and butanol in 25 ml beaker (1 drop of HC1, 1.5 ml of water and 3 ml of butanol ) is then added and stirred for one hour. The mixture thus obtained in the preceding step is refluxed for 2 hours at 90 °C and kept in freeze for overnight to obtain a functionalized silica sol. 15 ml of sol is thus obtained.7 ml of this functionalised silica sol is then mixed with 5 ml of toluene and is placed on rotavapour for removal of butanol and toluene. Again, 5 ml of toluene is added to mixture obtained in preceding step and placed on rotavapour for total removal of butanol.Finally 3 ml of sol is obtained. The final nano silica dispersion is 30 Wt %.
About 2 gm of polyacrylate with hydroxy functionality is taken in 10 ml sample bottle. Further, 0.3 gm polyisocyanate is added and mixed thoroughly. To this about 1.2 mL of silica sol is added and mixed thoroughly. With the help of a adjustable film applicator a coating is drawn on a glass plate with a thickness of 25 micron. The film is flashed for 5 minutes in open air and then cured at 120 °C for 20 minutes. The coating is transparent with pencil hardness of 2 H.
About 2 gm of dropoxy is taken in 10 ml sample bottle and is mixed with 1 gm of dromide.To this mixture, about 1.2 mL of silica sol prepared as above is added. A film of thickness 25 micron is drawn with the help of an applicator on a glass plate. The film is flashed for 3 minutes and then the glass plate is cured at 125°C for 30 minutes. The coating formed is transparent and very hard and shows good adhesion on the glass plate. Example 2
About 5.415 grams of Aldrich TEOS and 2.5 mililiters of glycidoxy propyl trimethoxy silane is taken in 50 mililiter single neck round bottom flask. This mixture is stirred for 5

minutes to obtain a reaction medium. To this reaction medium, a mixture of HC1, water and butanol in 25 ml beaker (1 drop of HC1, 1.5 ml of water and 3 ml of butartol) is then added and stirred for one hour. Further added 1 ml of methanol in the mixture obtained
from preceding step and reflux it for 2 hours at 90 °C and kept in freeze for overnight. 13 ml of sol is thus obtained and further added 10 ml of butyl acetate and distilled off at 117
°C to remove butanol until the volume of the solution became 11 ml. The final nano silica dispersion is 22.5 Wt %.
About 2 gm of dropoxy is taken in 10 ml sample bottle mixed with 1 gm of dromide and added about 0.38 ml of silica sol prepared as above. A film of thickness of 25 micron is drawn with the help of an applicator on a glass plate. The film is flashed for 3 minutes and
then the glass plate is cured at 125 °C for 30 minutes. The coating formed is transparent with the hardness of more than 3 H Example 3
About 5.415 g of TEOS, Aldrich and 2.5 ml of glycidoxy propyl trimethoxy silane is taken in 50 ml single neck round bottom flask and stirred for 5 minutes to obtain a reaction medium. To this reaction medium a mixture of HC1, water and butanol in 25 ml beaker (1 drop of Hcl, 1.5 ml of water and 3 ml of butanol) is added and stirred for one hour. Then added lml of methanol in the mixture obtained from preceding step and refluxed for 2
hours at 90 °C and kept in freeze for overnight. 13 ml of sol is obtained. Further, 10 ml of
butyl acetate is added to the obtained sol and then distilled off at 118 °C for removal of butanol to obtain 11 mililiters of sol. The final nano silica dispersion is 22.5 Wt %. About 2 gm of dropoxy is taken in 10 ml sample bottle and mixed with 1 gm of dromide and to this mixture further added about 0.49 ml of silica sol prepared as above. A film of thickness of 25 micron is drawn with the help of a applicator on a glass plate. The film is

flashed for 3 mins and then the glass plate is cured at 125 °C for 30 minutes. The formed
coating is transparent.
Example 4
About 5.415 g of TEOS, Aldrich and 2.5ml of glycidoxy propyl trimethoxy silane is taken
in 50 ml round bottom flask and stirred for 5 minutes to obtain a reaction medium. To this
reaction medium a mixture of HC1, water and butanol in 25 ml beaker (1.5 ml of water
with PH 2 and 3 ml of butanol) is added and stirred for one hour. Then added 1 ml of
methanol in the mixture obtained from preceding step and refluxed for 2 hours at 90 °C. 13 ml of sol is obtained. Further, 10 ml of butyl acetate is added to the obtained sol and
then distilled off at 117 °C for removal of ethanol and butanol to obtain 12 mililiters of sol. The final nano silica dispersion is 20.83 Wt %.
About 2 gm of dropoxy is taken in 10 ml sample bottle and mixed with 1 gm of dromide and to this mixture further added about 0.49 ml of silica sol prepared as above. A film of thickness of 25 micron is drawn with the help of a applicator on a glass plate. The film is
flashed for 3 mins and then the glass plate is cured at 125 °C for 30 minutes. The coating formed is transparent with a hardness of 4H. Example 5
About 5.415 g of Aldrich TEOS and 2.5ml of glycidoxy propyl trimethoxy silane is taken in 50 ml single neck round bottom flask and stirred for 5 minutes to obtain a reaction medium. To this reaction medium a mixture of HO,' water and butanol in 25 ml beaker (1.72 ml of water with PH 2 and 3 ml of butanol) is added and stirred for one hour. Then added 1ml of methanol into the mixture obtained from preceding step and refluxed for 2 hours at 90 °C. 13 ml of sol is obtained..Further 7 ml of toluene is added to the obtained sol and then distilled off at 117 °C for removal of ethanol and butanol to obtain a final sol

of 14 ml.
The final nano silica dispersion is 17.85 Wt %.
About 2 gm of dropoxy is taken in 10 ml sample bottle and mixed with 1 gm of dromide
and to this mixture further added about 1 ml of silica sol prepared as above. A film of
thickness of 25 micron is drawn with the help of a applicator on a glass plate. The film is
flashed for 3 mins and then the glass plate is cured at 125 °C for 30 minutes. The formed coating is transparent. Example 6
About 5.415 g of TEOS, Aldrich and 2.5ml of glycidoxy propyl trimethoxy silane is taken in 50 ml single neck round bottom flask and stirred for 5 minutes to obtain a reaction medium. To this reaction medium a mixture of HC1, water and butanol in 25 ml beaker (1.70 ml of water with PH 2 and 3 ml of butanol) is added and stirred for one hour. Then added 1ml of methanol into the mixture obtained from preceding step and refluxed for 2
hours at 90 °C. 13 ml of sol is obtained. Further 7 ml of toluene is added to the obtained
sol and then distilled off at 117 °C for removal of ethanol and butanol to obtain a final sol
of 14 ml.
The final nano silica dispersion is 17.85 Wt %.
About 2 gm of dropoxy is taken in 10 ml sample bottle and mixed with 1 gm of dromide
and to this mixture further added about 1 ml of silica sol prepared as above. A film of
thickness of 25 micron is drawn with the help of a applicator on a glass plate. The film is
flashed for 3 mins and then the glass plate is cured at 125 °C for 30 minutes. The formed
coating is transparent with a pencil hardness in the order of 4H.
Example 7
About 5.415 g of TEOS, Aldrich and 2.5ml of glycidoxy propyl trimethoxy silane is taken

in single neck round bootom flask and stirred for 5 minutes to obtain a reaction medium. To this reaction medium a mixture of HC1, water and butanol in 25 ml beaker (1,55 ml of water with PH 2 and 3 ml of butanol) is added and stirred for one hour. Then added 1ml of
methanol into the mixture obtained from preceding step and refluxed for 2 hours at 90 °C. 13 ml of sol is obtained. Further 7 ml of toluene is added to the obtained sol and then distilled off at 120 °C for removal of ethanol and butanol to obtain a final sol of 12 ml. The final nano silica dispersion is 20 Wt %.
About 2 gm of polyacrylate with hydroxy functionality is taken in 10 ml sample bottle. Further, 0.3 gm polyisocyanate is added and mixed thoroughly. To this about 1 mL of silica sol is added and mixed thoroughly and added 3 drops of aluminium acetyl acetonate. With the help of a adjustable film applicator a coating is drawn on a glass plate with a thickness of 25 micron. The film is flashed for 5 minutes in open air and then cured at 120 °C for 20 minutes. The coating is transparent with pencil hardness of 2 H. Example 8
About 5.415 g of TEOS, Aldrich and 2.5ml of glycidoxy propyl trimethoxy silane is taken in 50 ml single neck round bottom flask and stirred for 5 minutes to obtain a reaction medium. To this reaction medium a mixture of HC1, water and butanol in 25 ml beaker (1.55 ml of water with PH 2 and 3 ml of butanol) is added and stirred for one hour. Then added 1 ml of methanol into the mixture obtained from preceding step and refluxed for 2
hours at 90 °C. 11 ml of sol is obtained. Further, 6 ml of butyl acetate is added to the
obtained sol and then distilled off at 117 °C for removal of ethanol and butanol to obtain a
final sol of 12ml.
The final nano silica dispersion is 20 wt %.
About 2 gm of polyacrylate with hydroxy functionality is taken in 10 ml sample bottle.

Further, 0.3 gm polyisocyanate is added and mixed thoroughly. To this about 1 mL of silica sol is added and mixed thoroughly and added 3 drops of aluminium acetyl acetonate. With the help of an adjustable film applicator a coating is drawn on a glass plate with a thickness of 25 micron. The film is flashed for 5 minutes in open air and then cured at 120 °C for 20 minutes. The coating is transparent. Example 9
About 8.122 g of TEOS Aldrich and 3.68 ml of glycidoxy propyl trimethoxy silane is taken in 50 ml single neck round bottom flask and stirred for 5 minutes to obtain a reaction medium. To this reaction medium a mixture of HC1, water and butanol in 50 ml beaker (2.1 ml of water with PH 2 and 3 ml of butanol) is added and stirred for one hour. Then added 2 ml of methanol into the mixture obtained from preceding step and refluxed for 2
hours at 90 °C. 21ml of sol is obtained. Further. 10 ml of toluene is added to the obtained
sol and then distilled off at 117 °C for removal of butanol to obtain a final sol of 17 ml. The final nano silica dispersion is 20 Wt %.
About 2 gm of polyacrylate with hydroxy functionality is taken in 10 ml sample bottle. Further, 0.3 gm polyisocyanate is added and mixed thoroughly. To this about 0.38 mL of silica sol is added and mixed thoroughly. With the help of an adjustable film applicator a coating was drawn on a glass plate with a thickness of 25 micron. The film is flashed for 5
minutes in open air and then cured at 120 ° C for 20 minutes. The coating is transparent with a pencil hardness of 2 H.
About 2 gm of dropoxy is mixed with 1 gm of dromide in 10 ml sample bottle and to that , about 0.49 ml of silica sol prepared as above is added. A film of thickness of 25 micron is drawn with the help of an applicator on a glass plate. The film is flashed for 3 minutes and
then the glass plate is cured at 125 °C for 30 minutes. The coating formed is transparent

with a pencil hardness of above 4 H
Example 10
About 8.122 g of Aldrich TEOS and 3.68 ml of glycidoxy propyl trimethoxy silane is
taken in 50 ml single neck round bottom flask and stirred for 5 minutes to obtain a
reaction medium. To this reaction medium a mixture of HC1, water and butanol in 25 ml
beaker (2.1 ml of water with PH 2 and 3 ml of butanol) is added and stirred for one hour.
Then added 2 ml of methanol into the mixture obtained from preceding step and refluxed
for 2 hours at 90 °C. 21ml of sol is obtained. Further, 10 ml of toluene is added to the
obtained sol and then distilled off at 117 °C for removal of butanol to obtain a final sol of
17 ml.
The final nano silica dispersion is 17.85 Wt %.
About 2 gm of polyacrylate with hydroxy functionality is taken in 10 ml sample bottle. Further, 0.3 gm polyisocyanate is added and mixed thoroughly. To this about 0.38 mL of silica sol is added and mixed thoroughly. With the help of an adjustable film applicator a coating was drawn on a glass plate with a thickness of 25 micron. The film is flashed for 5
minutes in open air and then cured at 120 ° C for 20 minutes. The coating is transparent with a pencil hardness of 2 H.
About 2 gm of dropoxy is mixed with 1 gm of dromide in 10 ml sample bottle and to that about 0.49 ml of silica sol prepared as above is added. A film of thickness of 25 micron is drawn with the help of an applicator on a glass plate. The film is flashed for 3 minutes and
then the glass plate is cured at 125 °C for 30 minutes. The coating formed is very good without any haziness. Example 11 About 5.415 g of Aldrich TEOS is mixed with 2.5 ml of glycidoxy propyle

trimethoxysilane in 50 ml single neck round bottom flask and stirred for 5 minutes to obtain a reaction medium. To this reaction medium a mixture of HC1, water and butanol in 25 ml beaker (1.55 ml of water with pH 2 and 9 ml of butanol) is added and stirred for one hour. Then added 4 ml of methanol into the mixture obtained from preceding step and
refluxed for 2 hours at 90 °C. 14.5 ml of sol is obtained. Further, 7 ml of toluene is added
to the obtained sol and then distilled off at 117 °C for removal of butanol to obtain a final
sol of 11 ml.
The final nano silica dispersion is 22.72 Wt %.
About 2 gm of dropoxy is mixed with 1 gm of dromide in 10 ml sample bottle and to that
about 0.49 ml of silica sol prepared as above is added. A film of thickness of 25 micron is
drawn with the help of an applicator on a glass plate. The film is flashed for 3 minutes and
then the glass plate is cured at 125 °C for 30 minutes. The coating formed is transparent
with scratch resistance.
Example 12
About 10.83 g of Aldrich TEOS is mixed with 5ml of glycidoxy propyl trimefhoxy silane
in 50 ml single neck round bottom flask followed by stirring for 5 minutes to obtain a
reaction medium. A mixture of HC1, water and butanol in 25 ml beaker (3.10 ml of water
with PH 2 and 17.5 ml of butanol) is added to the reaction medium and is stirred for one
hour. The mixture thus obtained is refluxed for 2 hours at 90 °C. 35 milliliters of sol is
obtained. About 25 ml of sol is mixed with butyl acetate and distilled off at 117 °C to remove butanol.Finally 21 ml sol was obtained. The final nano silica dispersion is 23.80 Wt %.
About 2 gm of dropoxy is taken in 10 ml sample bottle and is mixed with 1 gm of dromide.To this mixture, about 0.49 ml of silica sol prepared above is added. Further, a

film of thickness 25 micron is drawn with the help of an applicator on a glass plate. The
film is flashed for 3 minutes and then the glass plate is cured at 125 °C for 30 minutes.
The coating formed is transparent.
Example 13
About 10.83 g of Aldrich TEOS is mixed with 5 ml of glycidoxy propyl trimethoxy silane
in 50 ml round bottom flask followed by stirring for 5 minutes to obtain a reaction
medium.A mixture of HC1 and water in 25 ml beaker (3.1 ml of water with PH 2 and 3 ml
of butanol) is then added to the reaction medium and is stirred for one hour.The mixture
thus obtained is refluxed for 2 hours at 90 °C.Thereafter, 1.2 ml chloro trimethyl silane is added to the mixture obtained in preceding step.29 ml sol is thus obtained. The sol is
mixed with 16 ml of butyl acetate and distilled off at 117 °C to remove butanol.Finally 19ml sol is obtained. The final nano silica dispersion is 25.64 Wt %. About 2 gm of dropoxy is taken in 10 ml sample bottle and is mixed with 1 gm of dromide. To this mixture, about 0.5 ml of silica sol prepared as above is added. A film of thickness 25 micron is drawn with the help of an applicator on a glass plate. The film is
flashed for 3 minutes and then the glass plate is cured at 125 °C for 30 minutes. The final coating on the glass plate is transparent with a pencil hardness of 4H. Example 14
About 5.415 g of Aldrich TEOS is mixed with 2.5ml of glycidoxy propyl trimethoxy silane in 50 ml single neck round bottom flask followed by stirring for 5 minutes to obtain a reaction medium.A mixture of HC1 and water in 25 ml beaker (1.5 ml of water with PH 2 and 1.5 ml of butanol) is then added to the reaction medium and is stirred one hour. This mixture is then refluxed for 2 hours at 90 °C. After refluxing, 1.2 ml of chloro trimethyl silane is then added to the mixture. 13.5 ml of sol is thus obtained. The sol is then mixed

with 9 ml of butyl acetate and distilled off at 117 °C to remove butanol. Finally, 8ml of sol
is obtained.
The final nano silica dispersion is 31.25 Wt %.
About 2 gm of polyacrylate with hydroxy functionality is taken in 10 ml sample bottle and
is mixed with 0.3 gm polyisocyanate and mixed thoroughly. To this about 0.5 ml of silica
sol is added and mixed thoroughly. With the help of an adjustable film applicator a coating
was drawn on a glass plate with a thickness of 25 micron. The film is flashed for 5 minutes
in open air and then cured at 120 °C for 20 minutes. The coating is transparent with a pencil hardness of 3 H. Example 15
About 10.83 g of Aldrich TEOS is mixed with 5 ml of glycidoxy propyl trimethoxy silane in 50 ml single neck round bottom flask followed by stirring for 5 minutes to obtain a reaction medium. A mixture of HC1 and water in 25 ml beaker (3 ml of water with PH 2 and 2 ml of butanol) is then added to the reaction medium and is stirred for one hour. To this mixture, 6 ml of methanol is added and the mixture is then refluxed for 2 hours at 90
°C. After refluxing, 2.4 ml of chloro trimethyl silane is added to the mixture obtained in the preceding step. 29 ml of sol is obtained. Sol is then mixed with 16 ml of butyl acetate
and distilled off at 117 °C to remove butanol. Finally, 17 ml of sol is obtained. The final nano silica dispersion is 31.25 Wt %.
About 2 gm of polyacrylate with hydroxy functionality is taken in 10 ml sample bottle with around polyisocyanate 0.3 gm and is mixed thoroughly. To this, about 0.5 ml of silica sol is added and mixed thoroughly- With the help of an adjustable film applicator a coating is drawn on a glass plate with a thickness of 25 micron. The film is flashed for 5 minutes
in open air and then cured at 120 °C for 20 minutes. The coating is transparent with pencil
1 —T

hardness of 2 H.
SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW
A method for preparing a coating composition comprising preparing a diol functionalized metal nanoparticles by reacting a metal precursor with an epoxy based silane in presence of hydrochloric acid and adding the diol functionalized metal nanoparticles and a crosslinker to an organic polymer, the crosslinker capable of forming a covalent bond with the diol and forming a covalent bond with the organic polymer.
Such method(s), wherein the epoxy based silane is glycidoxy propyl trimethoxy silane.
Such method(s), wherein the hydrochloric acid is added externally.
Such method(s), wherein chlorosilane is added along with glycidoxy propyl trimethoxy silane.
Such method(s), wherein the metal precursor is tetraethylorthosilicate.
Such method(s), wherein the metal precursor is added to the silane in presence of alcohol and water.
Such method{s)T wherein the organic polymer is polyacrylate-ol or polyester-ol.
Such method(s), wherein the crosslinker is polyisocyanate.
Such method(s), wherein the organic polymer is epoxy resin.
Such method(s), the crosslinker is polyamide.
A coating composition comprising diol finctionalised metal nanoparticles, an organic polymer and a crosslinker wherein the crosslinker forms a covalent bond with diol functionalized metal nanoparticles and the organic polymer.
Such coating composition(s), wherein the diol functionalized metal nanoparticles are diol functionalized silica nanoparticles.

Such coating composition(s), wherein the organic polymer is polyacrylate-ol or polyester-ol.
Such coating composition(s), wherein the crosslinker is polyisocyanate. Such coating composition(s), wherein the organic polymer is epoxy resin. Such coating composition(s), wherein the crosslinker is polyarnide.
INDUSTRIAL APPLICABILITY
The coating composition described above forms a transparent coating without any haziness. Moreover, the coating composition possesses improved mechanical properties such as hardness, antiscratch properties, abrasion resistance, etc.

WE CLAIM:
1. A method for preparing a coating composition comprising:
preparing a diol functionalized metal nanoparticles by reacting a metal precursor with an epoxy based silane in presence of hydrochloric acid; and - adding the diol functionalized metal nanoparticles and a crosslinker to an organic polymer, the crosslinker capable of forming a covalent bond with the diol and forming a covalent bond with the organic polymer.
2. A method for preparing a coating as claimed in claim 1 wherein, the epoxy based silane is glycidoxy propyl trimethoxy silane.
3. A method for preparing a coating as claimed in claim 2 wherein, the hydrochloric acid is added externally.
4. A method for preparing a coating as claimed in claim 2 wherein, chlorosilane is added along with glycidoxy propyl trimethoxy silane.
5. A method for preparing a coating as claimed in claim 1 wherein, the metal precursor is tetraethylorthosilicate.
6. A method for preparing a coating as claimed in claim 1 wherein, the metal precursor is added to the silane in presence of alcohol and water.

7. A method for preparing a coating as claimed in claim 1 wherein, the organic polymer is polyacrylate-ol or polyester-ol.
8. A method for preparing a coating as claimed in claim 7 wherein, the crosslinker is polyisocyanate.
9. A method for preparing a coating as claimed in claim 1 wherein, the organic polymer is epoxy resin. ■
10. A method for preparing a coating as claimed in claim 9 wherein, the crosslinker is polyamide.
11. A coating composition comprising diol finctionalised metal nanoparticles, an organic polymer and a crosslinker wherein the crosslinker forms a covalent bond with diol functionalized metal nanoparticles and the organic polymer.
12. A coating composition as claimed in claim 11, wherein the diol functionalized metal nanoparticles are diol functionalized silica nanoparticles.
13. A coating composition as claimed in claim 11, wherein the organic polymer is polyacrylate-ol or polyester-ol.
14. A coating composition as claimed in claim 13, wherein the crosslinker is polyisocyanate.

15. A coating composition as claimed in claim 11, wherein the organic polymer is epoxy resin.
16. A coating composition as claimed in claim 15, wherein the crosslinker is polyamide.
17. A method for preparing a coating composition substantially as herein described.
18. A coating composition substantially as herein described.