Claims:We Claim:
1. Polysiloxane based clear coat formulation as a two or three component formulation comprising
(i) 60-85 wt. % of resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin, said acrylic resin comprising a reaction product of hydroxyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g and silanol and alkoxy functional organosiloxane resin, as a liquid base component;
(ii) 10-25 wt.% of hardener/curing component selected from amines, aminosilanes, blocked aminosilanes, silicone resins including organosiloxane intermediates/oligomers, and combinations thereof;
iii) 0.2-1.2 wt.% accelerators/catalysts selected from Dibutyltin dilaurate (DBTDL) and Organic titanates, with the balance being solvents.
2. Polysiloxane based clear coat formulation as claimed in claim 1 as a storage stable formulation based on ASTM D 1849 – 95 standards that is configured to provide a highly durable corrosion resistance coating over Ni-Cr plated and PVD faucet with regard to nail hardness, adhesion, salt spray and CASS.
3. Polysiloxane based clear coat formulation as claimed in claims 1 or 2 wherein said hardener curing component comprises a combination of aminosilanes and organosiloxane intermediates/oligomers selected from methyl/phenyl functional organopolysiloxanes with hydroxyl or alkoxy functionality, said combination.
4. Polysiloxane based clear coat formulation as claimed in claims 1-3 as a two-component formulation wherein when the hardener involves a combination of amino silicone & organosiloxane intermediates/oligomers, the formulation passes both storage stability and corrosion resistant tests.
5. Polysiloxane based clear coat formulation as claimed in claims 1-4 wherein said formulation enables a cured resin when said liquid resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin is cured with liquid hardener combination (>99% solids) together with curing component/ accelerator adapted for curing/ drying to impart desired hardness.
6. Polysiloxane based clear coat formulation as claimed in claims 1-5 wherein said component (i) resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin have epoxy equivalent weight in the range of 500-700 g/eq. as a liquid base component having viscosity on gardener scale of T V at temperatures of 25 ?C.

7. Polysiloxane based clear coat formulation as claimed in claims 1-6 wherein said resin blend involves stable flowable resin blend (i) wherein said epoxy resin/s of said resin blend is preferably at least one cycloaliphatic epoxy resin or combinations thereof, said resin blend including siloxane oligomer grafted glycidyl functional acrylic resin comprising silanol and alkoxy functional organosiloxane resin grafted onto base hydroxyl and glycidyl functional acrylic resin enabling said siloxane oligomer grafted glycidyl functional acrylic resin having overall 5-9 % epoxy percent on resin solids, 10-40% silicone % on resin solids, epoxy equivalent wt. in the range of 500-700 g/ eqv., and
wherein said silicone oligomer grafted glycidyl functional acrylic resin comprises hydroxyl and glycidyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g stabilized by incorporation of mono-functional alcohol including methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol preferably isobutanol; and
wherein the balance ingredients of said formulation being conventional paint ingredients including solvents, coupling agents.
8. Polysiloxane based clear coat formulation as claimed in claims 1-7 wherein said siloxane oligomer grafted hydroxyl and glycidyl functional acrylic resin of component (i) is a reaction product of
(a) 60-90 wt.% hydroxyl and glycidyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g, and,
(b) 10-40 wt.% of organosiloxane oligomer with methoxy functionality enabling epoxy equivalent wt. in the range of 500-700 (g/ eq.) of said siloxane oligomer grafted base hydroxyl and glycidyl functional acrylic resin.
9. Polysiloxane based clear coat formulation as claimed in claims 1-8 wherein said hydroxyl and glycidyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g is a polymer of monomers including esters of acrylic/methacrylic acid, hydroxy functional and glycidyl functional acrylate monomers that includes monomers of 0-10 % Methyl methacrylate, 3-14 % Butyl Acrylate, 0-5 % Butyl Methacrylate, 9-22 % Glycidyl acrylate/ Glycidyl Methacrylate (GMA), 0-15 % Hydroxyethyl methacrylate (HEMA), hydroxyl ethyl acrylate 0-15 % (HEA).
10. A process for preparing said polysiloxane based clear coat formulation as claimed in claims 1-9 comprising the steps of
(i) providing 60-85 wt. % of resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin, said acrylic resin comprising a reaction product of hydroxyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g and silanol and alkoxy functional organosiloxane resin, as a liquid base component preferably having epoxy equivalent weight in the range of 500-700 g/eq., solid content ~70% as a liquid base component having viscosity on gardener scale of T-V at temperatures of 25 ?C.
(ii) providing 10-25 wt.% of hardener/curing component selected from amines, aminosilanes, blocked aminosilanes, silicone resins including organosiloxane intermediates/oligomers, and combinations thereof;
iii) providing 0.2-1.2 wt.% accelerators/catalysts selected from Dibutyltin dilaurate (DBTDL) and Organic titanates, with the balance being solvents.
(iv) curing and obtaining therefrom clear and glossy films with flexibility and adhesion characteristics with good salt spray resistance and nail hardness.
11. The process for preparing polysiloxane based clear coat formulation as claimed in claim 10 wherein said component of step (i) of resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin, said acrylic resin comprising a reaction product of hydroxyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g and silanol and alkoxy functional organosiloxane resin is obtained based on the following steps of
(a) Radical polymerizing mixture of monomers including esters of acrylic/methacrylic acid, hydroxy functional and glycidyl functional acrylate monomers including monomers of 0-10 % Methyl methacrylate, 3-14 % Butyl Acrylate, 0-5 % Butyl Methacrylate, 9-22 % Glycidyl acrylate/ Glycidyl Methacrylate (GMA), 0-15 % Hydroxyethyl methacrylate (HEMA), hydroxyl ethyl acrylate 0-15 % (HEA) in organic solvents including butyl acetate, cellosolve acetate, xylene as solvents with initiator including TBPB (Tertiary butyl perbenzoate) as initiator in the presence of nitrogen and heating in temperature range of 140-150 deg C wherein said mixture of monomers and initiator are added dropwise over 4 hours by maintaining temperature range of 140-150 deg C followed by carrying out digestion for 3 hours at 140-150 deg C with addition of extra initiator during last hour of digestion and obtaining therefrom both –OH and glycidyl functional acrylic resin having -OH value in the range of 50 to 150 mg KOH/g;
(b) condensation polymerizing –OH and glycidyl functional acrylic resin of step (a) above with silanol and alkoxy/methoxy/ethoxy functional organosiloxane resin involving tetra isopropyl titanate catalyst by starting heating at 60?C followed by adding the mixture of organosiloxane resin in the presence of mono-functional alcohol dropwise to the resin and said catalyst over a period of 30 to 40 minutes while continuing to stir and maintaining temperature at 60-70?C and thereafter gradually heating the contents to 120?C over a period of 1-3 hours at 120 ?C and maintaining temperature while stirring to attain single phase clear droplet indicating reaction termination to obtain methanol as by-product and siloxane oligomer grafted glycidyl functional acrylic resin;
(c) blending of 5-9 % epoxy resin with the above siloxane oligomer grafted glycidyl functional acrylic resin obtained in step (b) above including blending said epoxy resin at any stage of the said process during –OH and glycidyl functional acrylic resin preparation step (a) or after step (a) and during preparation of siloxane oligomer grafted glycidyl functional acrylic resin to obtain said resin blend.
12. The process for preparing polysiloxane based clear coat formulation as claimed in claims 10 or 11 as cured clear coat formulation wherein
(i) 60-85 wt. % of said resin blend epoxy polysiloxane based hybrid resin having epoxy equivalent weight in the range of 600 to 700 g/equivalent as a liquid base component having viscosity on gardener scale of T-V at temperatures of 25 ?C is cured with (ii) 10-25 wt.% of hardener/curing component selected from amines, aminosilanes, blocked aminosilanes, silicone resins including organosiloxane intermediates/oligomers, and combinations thereof in the presence of (iii) 0.2-1.2 wt.% Accelerator selected from Dibutyltin dilaurate (DBTDL) and Organic titanates as curing catalyst to enable clear and glossy films with flexibility and adhesion characteristics with good salt spray resistance and nail hardness.

Dated this the 31st day of March, 2022 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)
IN/PA-199

, Description:
FIELD OF INVENTION
The present invention relates to protective hybrid polysiloxane clear coat formulation/composition for Nickel-chromium plated and physical vapor deposited (PVD) metal alloys, and more particularly, the present invention relates to design of a protective clear hybrid polysiloxane based coating formulation suitable for nickel chromium (Ni-Cr) plated and physical vapor deposited (PVD) metal alloys used in faucets to enhance the service life.

BACKGROUND ART
Electrodeposited nickel is widely used in conjunction with chromium plating in different metal alloy as faucets for corrosion protection. Generally, faucets items are electroplated with Nickel plus chromium or copper plus Nickel plus chromium at defined individual thicknesses to impart both appealing surface decor and corrosion protection performance confirming to ASTM B458. PVD (physical vapour deposited) coated faucets bring rich aesthetic appeal and better performance. However, such Ni-Cr plating or PVD coating have limited corrosion protection performance. Other alternates reported to address this problem are based on pigmented organic coatings like powder coating or PTFE. However, such coatings spoil the original décor of the Ni-Cr or PVD coating.
These faucets are exposed to varying environmental conditions such as high humidity, saline atmosphere, chemicals and aggressive mechanical stresses in their service life. Such exposure to varying environmental conditions lead to rapid corrosion and consequent deterioration. As a result, many manufacturers and engineers of different industrial fields strive to improve the protective properties of Ni-Cr plated or PVD coated faucets. Most of the prior work is focused towards improving the quality of Ni-Cr plating or PVD coating thereby enhancing the durability of the faucet. There are attempts to enhance the durability through an additional layer of organic coatings like powder polyester, PTFE or PFE, however, all these approaches spoil the original décor and characteristic finish of Ni-Cr plating or PVD coating.
On the prior works, references are drawn to the following:
JP5180644B2 teaches nickel elution prevention method for copper alloy wetted parts wherein copper alloy wetted device is plated with nickel a protective film forming component containing benzotriazole and low-polymerized polyethylene.
JP2013083007A discloses a method for managing a treatment liquid for forming a protective film, with which the elution of nickel is prevented even when contact with a liquid such as tap water occurs, in a valve for an aqueduct, a valve for feeding water/hot water, a fitting etc. In a protective film forming process with an alkaline treatment liquid into which water of a washing process for cleaning a treatment liquid, used in a process for removing lead or/and nickel, mixes, the concentration of a component forming the protective film.
DE10257133A1 is directed to a chromium plated water faucet fitting that has inner fluoropolymer coating, to prevent chromium entering the drinking water with the water faucet fitting, especially hot/cold water mixers and shut-off assemblies, is metal with chromium plated visible surface. The inner surfaces, defining water flow paths, are coated with fluoropolymer to prevent chromium being deposited on them during plating; or the coating covers chromium deposits from the plating, to prevent chromium entering the drinking water.
CN106189561 discloses an environment friendly ceramic material for water faucet that is prepared according to a formula comprising raw materials at varying concentrations such as fluorocarbon resin, organosilicone oil, naphtha, polydimethylsiloxane, absolute ethyl alcohol, alkylphenol polyoxyethylene and other additives. The environment-friendly ceramic coating material for the water faucet has the advantages of corrosion resistance, wear resistance, high adhesive force, bright and clean appearance, and compact coating structure.
CN111518427 teaches a thermochromic coating composed of a faucet body, a primer coating and a thermochromic coating wherein the surface of the faucet body is uniformly coated with the thermochromic coating, the thermochromic coating being formed by uniformly spraying primer on the surface of the faucet body through a paint spraying machine, then baking the faucet body and then spraying a thermochromic material, and the thermochromic coating is an organic chromophoric coating with a chemical structure.
CN105778707 is directed to inner-wall protective coating for manufacturing faucet and relates to the technical field of hardware device processing and production. The inner-wall protective coating is characterized by being prepared from, by weight, modified epoxy resin, chitosan, wollastonite powder, carboxymethylcellulose, ethylene glycol dimethacrylate, triethylene glycol, anti-aging agent and other additives.
SU234093A1 teaches method for forming polymer coating on metal substrate and provides for an article comprising a substrate; a polymer coating; and an intermediate layer disposed between the substrate and the polymer coating, the intermediate layer comprising a carbon composite, wherein the carbon composite comprises carbon and a binder.

US20090048394A1 involves fast-curing modified siloxane compositions comprising an alkoxy- or silanol-functional silicone intermediate, at least one amine reactive ingredient selected from the group consisting of acetoacetate-functional ingredients, acrylate-functional ingredients, and mixtures thereof, an epoxy-functional ingredient, a curing agent selected from the group consisting of amines, aminosilanes, ketimines, aldimines and mixtures thereof, and water. The epoxy and acrylate functional ingredients of this prior art do not share a common polymeric backbone as epoxy polysiloxane precursor material with controlled epoxy content.
WO1996016109A is directed to epoxy polysiloxane made up of: (a) a resin component which includes a non-aromatic epoxy resin having at least two 1,2-epoxy groups per molecule; a polysiloxane and an organooxysilane; (b) an amine hardener component substituted in part or in whole by an aminosilane; (c) an organotin catalyst; and (d) an aggregate or pigment component. The hardener and epoxide resin react to form a cured linear epoxy polymer. The polysiloxane and/or organooxysilane undergo a hydrolysis reaction which produces silanol. The silanol undergoes polycondensation forming a linear epoxy-modified polysiloxane polymer. Thus, teaches epoxy polysiloxane together with a hardener component without the involvement of any acrylic polyol component in the epoxy polysiloxane resin.
WO2019107124 teaches providing a coating material composition which can form a coating film which can maintain appearance and gloss over a long period of time, and has high coating film hardness and flexibility, and excellent adhesiveness to an epoxy resin anticorrosive coating film. The acrylic polysiloxane resin coating material composition of this prior art contains: a silicone resin (A); a compound (B) having one or more functional groups capable of the Michel addition reaction with an unsaturated double bond in an acryloyloxy group, and one or more alkoxy groups bonded to silicon; an aliphatic urethane acrylate oligomer (C) having a cyclic structure and having three or more functional groups; and a di-functional acrylate monomer (D) not having an ether structure (provided that the ether structure in the acryloyloxy group is excluded) or an aromatic ring, wherein the mass ratio of the total amount of the compounds (A) and (B) to the total amount of the acrylate oligomer and the acrylate monomer is 40:60-70:30. This prior art is based on the involvement of urethane oligomer.
Polyurethane and/or Polysiloxane Modified Epoxy Based on Acrylic Polyol and Tolonate, by Evi Triwulandari Indonesian Institute of Sciences January 2013, Conference: The International Conference on the Innovation in Polymer Science and Technology 2013 (IPST2013) Yogyakarta, Indonesia, October 7 –10, 2013At: Yogyakarta, Indonesia, discloses hybrid coating products that were synthesized from polyurethane and/or polysiloxane modified epoxy based on acrylic polyol and tolonate. Hybrid coating which synthesized were epoxy-polyurethane, epoxy-polysiloxane and epoxy-polyurethane-polysiloxane. Hybrid coating from epoxy-polyurethane was synthesized by reacting epoxy, acrylic polyol and tolonate.
IN201821049328/WO2020139642 is directed to a curable silicone-based composition comprising a hybrid silicone polymer, a catalyst, and a filler. In embodiments, this prior technology provides a curable silicone composition comprising a polymer A comprising an organic molecule or a siloxane molecule comprising an alkoxy radical, a hydroxyl radical, an isocyanate radical, a primary amine, or a carboxylic radical even epoxy radical; optionally a polymer B comprising an organic molecule, a siloxane molecule, or a hybrid-siloxane molecule; a catalyst; and a filler.
CN102304323 teaches a room temperature curable Ph silicone resin conformal coating material containing: (A) Ph silicone resin-linear polysiloxane block copolymer or Me Ph silicone-linear polysiloxane block copolymer 40-88, (B) alkoxysilane (R2 4-xSi(OR1)x) 1-10, (C) amino- or epoxy-containing silane coupling agent 0.2-5, (D) organic Ti compound 0.05-3, (E) organic phosphate flame retardant synergist 0.02-0.2, and (F) organic hydrocarbon solvent or low mol. wt. siloxane 10-58 wt%. Does not include any epoxy polysiloxane nor any acrylic polyol component in the epoxy polysiloxane.
CN112300680 teaches thermal insulation coating comprising sealing layer, reflective thermal insulating layer and weather-resistant surface layer, wherein the sealing layer is formed by an epoxy sealing primer or an anticorrosive primer, the reflective heat insulation layer is formed by polyurethane intermediate paint containing A1 component and B1 component, wherein the A1 component includes polyether polyol, silicone epoxy hybrid resin, hydroxy acrylic resin, filler, and film forming aid Agent M, solvent E, and the B1 component includes hexamethylene diisocyanate trimer, triethoxyaminosilane, and solvent F, the weather-resistant surface layer is formed by a fluorocarbon topcoat containing A2 component and B2 component, wherein, the A2 component includes flexible fluorocarbon resin, nano-titanium dioxide, flaky aluminum powder, aluminum silver paste, film-forming assistant N, and solvent G, the B2 component contains crosslinking agent and solvent H. The reflective thermal barrier layer, as per its A1 component is stated to comprise in parts by mass: 45-65 parts of polyether polyol, 4-14 parts of organic silicon epoxy hybrid resin, 4-14 parts of hydroxyl acrylic resin, 15-36 parts of filler, 0.5-5 parts of film-forming assistant M and 0.5-4 parts of solvent E. The silicone epoxy hybrid resin of this prior art does not have the acrylic polyol component in the same backbone with select epoxy equivalent levels.
While there have been attempts in the state of the art towards improving the quality of Ni-Cr plating or PVD coating thereby enhancing the durability of the faucet, there is a further need to explore for formulations that would not only retain the original décor and characteristic finish of Ni-Cr plating or PVD coating but would further enhance the corrosion protection performance of the faucet, so that such formulations, would curtail the need to enhance the durability through an additional layer of organic coatings like powder polyester, PTFE or PFE that spoil the original décor and characteristic finish of Ni-Cr plating or PVD coating.
Hence there is a need in the art to provide for polymeric clear coat formulations/ composition that would retain the original décor and characteristic finish of Ni-Cr plating or PVD coated substrates and yet would further enhance the corrosion protection performance of the faucet.

OBJECTS OF THE INVENTION
It is thus the basic object of the present invention to provide for a 2/ 3-component (2K/3K) hybrid polymeric clear coating formulation/composition based on an epoxy polysiloxane resin with acrylic polyol component and select epoxy equivalents, an amino silane curing agent and an accelerator that would enable excellent adhesion to Ni-Cr plated or PVD coated surface, to not only preserve original appearance of the faucet but would also enhance the corrosion resistance performance of the faucet.
It is another object of the present invention to provide for a high durable low thickness clear coating which would provide corrosion resistance in copper accelerated acetic acid salt spray (CASS); ASTM B368 and salt spray (ASTM B117).
It is still another object of the present invention to provide for low surface energy and high contact angle based said clear coating formulation/composition that would cause the water droplets to easily spread over the surface, would provide good adhesion over Ni-Cr plated and PVD faucet, and would also provide high abrasion resistance, impact strength and flexibility.
SUMMARY OF THE INVENTION
Thus, according to the basic aspect of the present invention there is provided polysiloxane based clear coat formulation as a two or three component formulation comprising
(i) 60-85 wt. % of resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin, said acrylic resin comprising a reaction product of hydroxyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g and silanol and alkoxy functional organosiloxane resin, as a liquid base component;
(ii) 10-25 wt.% of hardener/curing component selected from amines, aminosilanes, blocked aminosilanes, silicone resins including organosiloxane intermediates/oligomers, and combinations thereof;
iii) 0.2-1.2 wt.% accelerators/catalysts selected from Dibutyltin dilaurate (DBTDL) and Organic titanates, with the balance being solvents.
Preferably said polysiloxane based clear coat formulation is a storage stable formulation based on ASTM D 1849 – 95 standards that is configured to provide a highly durable corrosion resistance coating over Ni-Cr plated and PVD faucet with regard to nail hardness, adhesion, salt spray and CASS.
According to a preferred aspect of the present invention there is provided said polysiloxane based clear coat formulation wherein said hardener curing component comprises a combination of aminosilanes and organosiloxane intermediates/oligomers selected from methyl/phenyl functional organopolysiloxanes with hydroxyl or alkoxy functionality, said combination.
Preferably said polysiloxane based clear coat formulation is provided as a two-component formulation wherein when the hardener involves a combination of amino silicone & organosiloxane intermediates/oligomers, the formulation passes both storage stability and corrosion resistant tests.
According to yet another preferred aspect of the present invention there is provided said polysiloxane based clear coat formulation wherein said formulation enables a cured resin when said liquid resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin is cured with liquid hardener combination (>99% solids) together with curing component/ accelerator adapted for curing/ drying to impart desired hardness.
Preferably said polysiloxane based clear coat formulation is provided wherein said component (i) resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin have epoxy equivalent weight in the range of 500-700 g/eq. as a liquid base component having viscosity on gardener scale of T V at temperatures of 25 ?C.

According to yet another preferred aspect of the present invention there is provided said polysiloxane based clear coat formulation wherein said resin blend involves stable flowable resin blend (i) wherein said epoxy resin/s of said resin blend is preferably at least one cycloaliphatic epoxy resin or combinations thereof, said resin blend including siloxane oligomer grafted glycidyl functional acrylic resin comprising silanol and alkoxy functional organosiloxane resin grafted onto base hydroxyl and glycidyl functional acrylic resin enabling said siloxane oligomer grafted glycidyl functional acrylic resin having overall 5-9 % epoxy percent on resin solids, 10-40% silicone % on resin solids, epoxy equivalent wt. in the range of 500-700 g/ eqv., and
wherein said silicone oligomer grafted glycidyl functional acrylic resin comprises hydroxyl and glycidyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g stabilized by incorporation of mono-functional alcohol including methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol preferably isobutanol; and
wherein the balance ingredients of said formulation being conventional paint ingredients including solvents, coupling agents.

Preferably in said polysiloxane based clear coat formulation wherein said siloxane oligomer grafted hydroxyl and glycidyl functional acrylic resin of component (i) is a reaction product of
(a) 60-90 wt.% hydroxyl and glycidyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g, and,
(b) 10-40 wt.% of organosiloxane oligomer with methoxy functionality enabling epoxy equivalent wt. in the range of 500-700 (g/ eq.) of said siloxane oligomer grafted base hydroxyl and glycidyl functional acrylic resin.

According to yet another preferred aspect of the present invention said polysiloxane based clear coat formulation is provided wherein said hydroxyl and glycidyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g is a polymer of monomers including esters of acrylic/methacrylic acid, hydroxy functional and glycidyl functional acrylate monomers that includes monomers of 0-10 % Methyl methacrylate, 3-14 % Butyl Acrylate, 0-5 % Butyl Methacrylate, 9-22 % Glycidyl acrylate/Glycidyl Methacrylate (GMA), 0-15 % Hydroxyethyl methacrylate (HEMA), hydroxyl ethyl acrylate 0-15 % (HEA).

According to another aspect of the present invention there is provided a process for preparing said polysiloxane based clear coat formulation comprising the steps of
(i) providing 60-85 wt. % of resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin, said acrylic resin comprising a reaction product of hydroxyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g and silanol and alkoxy functional organosiloxane resin, as a liquid base component preferably having epoxy equivalent weight in the range of 500-700 g/eq., solid content ~70% as a liquid base component having viscosity on gardener scale of T-V at temperatures of 25 ?C.
(ii) providing 10-25 wt.% of hardener/curing component selected from amines, aminosilanes, blocked aminosilanes, silicone resins including organosiloxane intermediates/oligomers, and combinations thereof;
iii) providing 0.2-1.2 wt.% accelerators/catalysts selected from Dibutyltin dilaurate (DBTDL) and Organic titanates, with the balance being solvents.
(iv) curing and obtaining therefrom clear and glossy films with flexibility and adhesion characteristics with good salt spray resistance and nail hardness.

Preferably a process for preparing polysiloxane based clear coat formulation is provided wherein said component of step (i) of resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin, said acrylic resin comprising a reaction product of hydroxyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g and silanol and alkoxy functional organosiloxane resin is obtained based on the following steps of
(a) Radical polymerizing mixture of monomers including esters of acrylic/methacrylic acid, hydroxy functional and glycidyl functional acrylate monomers including monomers of 0-10 % Methyl methacrylate, 3-14 % Butyl Acrylate, 0-5 % Butyl Methacrylate, 9-22 % Glycidyl acrylate/ Glycidyl Methacrylate (GMA), 0-15 % Hydroxyethyl methacrylate (HEMA), hydroxyl ethyl acrylate 0-15 % (HEA) in organic solvents including butyl acetate, cellosolve acetate, xylene as solvents with initiator including TBPB (Tertiary butyl perbenzoate) as initiator in the presence of nitrogen and heating in temperature range of 140-150 deg C wherein said mixture of monomers and initiator are added dropwise over 4 hours by maintaining temperature range of 140-150 deg C followed by carrying out digestion for 3 hours at 140-150 deg C with addition of extra initiator during last hour of digestion and obtaining therefrom both –OH and glycidyl functional acrylic resin having -OH value in the range of 50 to 150 mg KOH/g;

(b) condensation polymerizing –OH and glycidyl functional acrylic resin of step (a) above with silanol and alkoxy/methoxy/ethoxy functional organosiloxane resin involving tetra isopropyl titanate catalyst by starting heating at 60?C followed by adding the mixture of organosiloxane resin in the presence of mono-functional alcohol dropwise to the resin and said catalyst over a period of 30 to 40 minutes while continuing to stir and maintaining temperature at 60-70?C and thereafter gradually heating the contents to 120?C over a period of 1-3 hours at 120 ?C and maintaining temperature while stirring to attain single phase clear droplet indicating reaction termination to obtain methanol as by-product and siloxane oligomer grafted glycidyl functional acrylic resin;

(c) blending of 5-9 % epoxy resin with the above siloxane oligomer grafted glycidyl functional acrylic resin obtained in step (b) above including blending said epoxy resin at any stage of the said process during –OH and glycidyl functional acrylic resin preparation step (a) or after step (a) and during preparation of siloxane oligomer grafted glycidyl functional acrylic resin to obtain said resin blend.

More preferably a process for preparing polysiloxane based clear coat formulation as cured clear coat formulation is provided wherein
(i) 60-85 wt. % of said resin blend epoxy polysiloxane based hybrid resin having epoxy equivalent weight in the range of 600 to 700 g/equivalent as a liquid base component having viscosity on gardener scale of T-V at temperatures of 25 ?C is cured with (ii) 10-25 wt.% of hardener/curing component selected from amines, aminosilanes, blocked aminosilanes, silicone resins including organosiloxane intermediates/oligomers, and combinations thereof in the presence of (iii) 0.2-1.2 wt.% Accelerator selected from Dibutyltin dilaurate (DBTDL) and Organic titanates as curing catalyst to enable clear and glossy films with flexibility and adhesion characteristics with good salt spray resistance and nail hardness.

DETAILED DESCRIPTION OF THE INVENTION
As discussed hereinbefore, the present invention provides for clear hybrid polysiloxane based coating formulation/composition suitable for nickel chromium (Ni-Cr) plated and physical vapor deposited (PVD) metal alloys used in faucets to enhance the service life by imparting excellent adhesion to Ni-Cr plated or PVD coated surface, said coating formulation/ comprising:
60-75 wt.% Resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin Epoxy polysiloxane resin which is organosiloxane based acrylic resin having epoxy equivalent weight in the range of 600 to 700 g/eq. (60 to 75% by weight of the resin composition), an amino silane curing agent and an accelerator, curable at ambient or at elevated temperatures.
Preferably in said clear hybrid polysiloxane based coating formulation said organosiloxane based acrylic resin is the key film forming material with an acrylic polyol component, said epoxy polysiloxane resin obtained by reacting with hydroxy acrylate monomer;
and wherein the cross linkers such as amino silanes, blocked amino silanes, amino functional polysiloxanes were found suitable to cure the coating;
and wherein accelerators are selected from Dibutyltin dilaurate (DBTDL) and Organic titanates in the proposed coating composition to improve crosslinking as well as improve efficacy of reaction, scratch resistance, hardness and adhesion with various substrates.

The key attributes of the coating formulation/composition are the following:
a) Polysiloxane clear coat composition can be either two component
b) Coating composition, when applied over metal surface, can be cured at ambient temperature or at set temperature by baking.
c) Key advantage is preserving the original décor and characteristic finish of Ni-Cr or PVD coating.
d) Coating possesses very good adhesion over Ni-Cr plated and PVD surface.
e) Resulting coating is flexible and having good abrasion resistance properties that are coated on select faucets to enhance its service life.
Thus, the two/ three component system based on organosiloxane as key film forming material of the present invention can either be ambient cured or cured at elevated temperatures.
Cross linkers such as amino silanes, blocked amino silanes, amino functional polysiloxanes found suitable to cure the coating. The silane compounds used to catalyze polysiloxane coatings are extremely effective adhesion promoters, resulting in tenacious adhesion over primers, metals, and concrete.
Organic titanate is used as accelerator in the said coating composition to improve crosslinking as well as improve efficacy of reaction, scratch resistance, hardness and adhesion with various substrates.
Importantly,
(i) the resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin when employed together with select levels of catalyst/ accelerator and silicon intermediate, and more preferably, when the hardener involves a combination of amino silicone & silicone intermediate, the formulation then appears to pass both storage stability and corrosion resistant tests
The silicone intermediates are methyl/phenyl functional organopolysiloxanes with hydroxyl or alkoxy functionality. This enabled to achieve high exterior durability. The epoxy equivalent weight of this resin is about ~500-700 g/eq. and solid content is ~70%.
(ii) To achieve desired properties to nickel chromium (Ni-Cr) plated and physical vapor deposited (PVD) metal alloys, series of experiments were conducted by varying the concentrations of epoxy polysiloxane resin, aminosilane + silicon intermediate and accelerator. These experiments were characterized for finish, hardness, adhesion, salt spray resistance (ASTM B117) copper accelerated acetic acid salt spray (ASTM B368) and storage stability. The experimental details and observations are tabulated and enclosed hereunder Table-5 and Table-6.

For Step (i) above towards preparation of resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin having epoxy equivalent weight in the range of 300-900 g/eq. (also including the comparative EEWs) including preferred EEW of 600 to 700 g/eq. is prepared based on the following as per the Table 1 (which cover EEW from 300 -900 and silicon content 10 -50%) as per below:
Comparative Example 1 (Not according to the present invention): A comparative epoxy polysiloxane resin with only cycloaliphatic epoxy resin (with EEW of 220 to 240 g/eq. and organosiloxane resin is synthesized as per the following procedure. 30% epoxy resin and 70% polysiloxane resin (Dow Corning 3074) is taken in the reactor and heated to 120 deg C till desired clarity and viscosity is attained to result in (epoxy equivalent weight) EEW of 300-900 g/eq. as in Table 6. Ortho xylene and isobutanol are taken as solvents. 2-ethylhexanoic acid is taken as the catalyst. A comparative epoxy polysiloxane resin is thus prepared with 70% solids and EEW of 300 to 900 g/eq. and a Gardner viscosity of R-S (measured at 25° C. with the use of a Gardner bubble viscometer), for the comparatives under Table 6.
Example 2 to 10: The recipes are given in Table 1 for Examples 2-10. Examples 2, 3, 8, 9 are in accordance with the present invention. Acrylic resin (both -OH functional and Epoxide functional) was synthesized including HEMA (Hydroxy ethyl methacrylate) or HEA (Hydroxy ethyl acrylate) and GMA (glycidyl methacrylate), Methyl methacrylate, Butyl Acrylate, Butyl Methacrylate, Hydroxyethyl methacrylate, as monomers in solvent (butyl acetate/cellosolve acetate/xylene) with TBPB (Tertiary butyl perbenzoate) as initiator. The siloxane oligomer can be blended or grafted onto the acrylic backbone. In the listed examples, blend of acrylic resin and the siloxane oligomer is incompatible and leads to haze and phase separation. Hence the siloxane oligomer is grafted onto acrylic resin via a condensation polymerization reaction using titanate catalyst. The hydroxyl groups combine with the methoxy groups of the siloxane oligomer. Methanol is the by-product of the condensation reaction. Epoxy resin is then blended into the resin. The epoxy resin can be blended in the resin at any stage of the resin preparation process (during acrylic resin synthesis, after preparation of the acrylic, after preparation of the acrylic siloxane reaction intermediate). Addition of a mono-functional alcohol improves the storage stability of the system. Resin was cured with 3-aminopropyltriethoxysilane (AMEO) and DBTDL catalyst (AHEW = 110.5) as per stoichiometry.
Part A procedure: The recipes are given in Table 1. Charge solvent to the reactor (4 neck glass flask with stirrer, nitrogen supply inlet, temperature sensor and condenser). Start stirring at 150 rpm. Start water supply to condenser. Start heating to 140-150 deg C. Add mixture of monomers and initiator dropwise over 4 hours maintaining Temp at 140-150 deg C. Carry out digestion for 3 hours at 140-150 deg C. Add extra initiator during last hour of digestion. Stop the heating, continue stirring and discharge and filter the batch at suitable temperature.
Part B procedure: Charge the acrylic resin made in Part A in the reaction vessel. Start water supply to condenser and flow of nitrogen gas to the reactor. Start stirring and add TYZOR TPT catalyst (tetra isopropyl titanate) to the reactor. Start heating to 60?C. Add the mixture of organosiloxane oligomer (Dow Corning DC 3074) and mono-functional alcohol dropwise to the resin and catalyst mixture over a period of 30 to 40 minutes while continuing to stir and maintaining temperature at 60-70?C. Gradually heat the contents to 120?C over a period of 1 hour. Maintain at this temperature while continuing to stir. During this time remove a small drop with a glass rod on a clear glass plate to check if a single-phase clear droplet is obtained. As soon as a clear drop is obtained (1 to 3 hours at 120?C), stop the heating, while continuing to stir. Filter/ discharge the batch at a suitable temperature.
Test data of exemplary resins is represented in Table 1 which spans EEW range of from 300-800 g/ eq. and silicon content 10-50% and includes comparative experiments without cycloaliphatic epoxy resin together with higher levels of cycloaliphatic epoxy, which even though have EEW levels of 300-800 g/ eq. and lead to clear and glossy coatings does not work for the clear coat formulation of the present invention.
Epoxy resin
The at least one cycloaliphatic epoxy resin compound comprises 1,4-cyclohexanedimethanol epoxy resin, or a mixture of 1,3-cyclohexanedimethanol epoxy resin and 1,4-cyclohexanedimethanol epoxy resin; a hydrogenated bisphenol A epoxy resin; or combinations thereof. Epoxy equivalent weight is in the range of 200 to 400 g/eq. The resin of the present invention works well with the said variants and their combinations.
Curing agents
Non-limiting examples of aminosilanes that may be used include aminopropyl trimethoxysilane, aminopropyl triethoxysilane, aminoethyl trimethoxysilane, aminoethyl triethoxysilane, methylaminopropyl trimethoxysilane, aminobutylmethyl dimethoxysilane, aminopropyl dimethyl methoxysilane, aminopropylmethyl dimethoxysilane, aminopropyldimethyl ethoxy silane, aminobutylmethyl dimethoxysilane, bis- (gamma-trimethoxysilylpropyl) amine, N- (3-methacryloxy-2-hydroxypropyl) -3-aminopropyl triethoxysilane, N- (3-acryloxy-2-hydroxypropyl) -3-aminopropyl triethoxysilane, (N, N-dimethylaminopropyl) trimethoxysilane, (N, N-diethyl-3-aminopropyl) trimethoxysilane, diethylaminomethyl triethoxysilane, bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, ?-aminopropyl trimethoxysilane, N- (2'-aminoethyl) -3-aminopropyl trimethoxysilane, N- (2'-aminoethyl) -3-aminopropyl triethoxysilane, N-Butyl-3-Aminopropyl triethoxysilane, N-octyl-3-aminopropyl trimethoxysilane, N-cyclohexyl-3-aminopropyl triethoxysilane, N- (3'-triethoxysilylpropyl) -piperazine, bis- (3-triethoxysilylpropyl) amine, tris- (3-trimethoxysilylpropyl) amine, N, N-dimethyl-3-aminopropyl triethoxysilane, N-methyl-N-butyl-3-aminopropyl triethoxysilane, N- (3'-aminopropyl) -3-aminopropyl triethoxysilane, N- (3'-triethoxysilylpropyl) morpholine, N-phenyl-gamma-aminopropyl trimethoxysilane and N-phenyl-gamma-amino-2-methylpropyl trimethoxysilane. All the curing agents and their combinations are workable for the purposes of the present invention.
Catalyst
In general, the coatings are capable of curing under ambient temperature and humidity conditions to a tack-free coating in 2 to 20 hours even without such a catalyst, but a catalyst may be preferred to give a faster cure. One example of a catalyst for Si—O—Si condensation is an alkoxytitanium compound, for example a titanium chelate compound such as a titanium bis(acetylacetonate) dialkoxide, e.g. titanium bis(acetylacetonate) diisopropoxide, a titanium bis(acetoacetate) dialkoxide, e.g. titanium bis(ethylacetoacetate) diisopropoxide, or an alkanolamine titanate, e.g. titanium bis(triethanolamine) diisopropoxide, or an alkoxy titanium compound which is not a chelate such as tetra(isopropyl) titanate or tetrabutyl titanate. The titanium compound can for example be used at 0.1 to 5% by weight of the binder. Corresponding alkoxide compounds of zirconium or aluminium are also useful as catalysts. An alternative catalyst is a nitrate of a polyvalent metal ion such as calcium nitrate, magnesium nitrate, aluminium nitrate, zinc nitrate or strontium nitrate. The level of calcium nitrate catalyst required is generally not more than 3% by weight of the binder, for example 0.05 to 3% by weight. Another example of a suitable catalyst is an organotin compound, for example a dialkyltin dicarboxylate such as dibutyltin dilaurate or dibutyltin diacetate. Such an organotin catalyst can for example be used at 0.05 to 3% by weight of the binder of the coating composition. Other compounds effective as catalysts in the coating compositions of the invention are organic salts, such as carboxylates, of bismuth, for example bismuth tris(neodecanoate). Organic salts and/or chelates of other metals such as zinc, aluminium, zirconium, tin, calcium, cobalt or strontium, for example zirconium acetylacetonate, zinc acetate, zinc acetylacetonate, zinc octoate, stannous octoate, stannous oxalate, calcium acetylacetonate, calcium acetate, calcium 2-ethylhexanoate, cobalt naphthenate, calcium dodecylbenzenesulphonate or aluminium acetate, may also be effective as catalysts.
Acrylic monomers
According to yet another preferred aspect of the present invention said coating composition is provided wherein said acrylic polyol comprises vinyl monomers, more specifically esters of acrylic or methacrylic acid including acrylates of alkyl, cycloalkyl, or aryl acrylates and methacrylates and aromatic vinyl compounds including styrene or multifunctional acrylic monomers such as diacrylates or triacrylates.
According to another preferred aspect of the present invention there is provided a coating composition wherein said acrylic polyol comprises hydroxyl monomers including hydroxyalkyl acrylates and hydroxyalky methacrylates such as 2-hydroxyethyl acrylate, 2- hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, hydroxyhexyl acrylate, hydroxyoctyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxpropyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, hydroxyhexyl methacrylate, hydroxyoctyl methacrylate, allyl and methally alcohol, butyl hydroxyethyl maleate and fumarate, butyl hydroxypropyl maleate and fumarate, including acetoacetate monomers such as acetoacetate ethyl methacrylate.
According to yet another preferred aspect of the present invention there is provided said coating composition comprising solvent or mixture of solvents upto 30 percent of the ingredients of the composition wherein said solvents include amyl acetate, toluene, ethyl acetate, butyl acetate, methoxy propyl acetate, acetone, methyl isobutyl ketone, methyl ethyl ketone, methyl amyl ketone, mineral spirits, ethylene glycol monoether acetates and other aliphatic, cycloaliphatic and aromatic hydrocarbons, such as xylene, esters, ethers, ketones, and other compatible solvents and reactive diluents of Cardura E10. The monomer variants and the solvent variants are all workable for the purposes of the present invention to give the desired results.
Polymerization Initiators
The free radical polymerization used to form the acrylic backbone is preferably carried out using conventional techniques, such as by heating the monomers in the presence of a free radical polymerization initiator, typically, tertiary butyl perbenzoate, tertiary butyl peroctoate, cumene hydroperoxide, benzoyl peroxide, di-tertiary butylperoxide, di-cumene peroxide, methyl ethyl ketone peroxide or similar peroxy compounds, or an azo compound such as azobisisobutyronitrile is employed. The amount of free radical polymerization initiator can be varied depending upon the desired molecular weight but 0.05-8 percent by weight based on the weight of total polymerizable monomers is typical. A preferred range is from 0.05 to 4 percent by weight. A mixture of two or more initiators may be used.
Table 1:
Part A EXPERIMENTS: (of acrylic resins: -OH and epoxide functional), Part B Experiments and
Part C Resin parameters of the paints based on different resins
S.NO. RAW MATERIAL 2 3 4 5 6 7 8 9 10
Part A EXPERIMENTS: (of acrylic resins: –OH and epoxide functional)
1 Methyl methacrylate 4.50 2.50 1.50 3.00 7.00 4.50 0.00 0.00 3.20
2 Butyl Acrylate 9.00 9.50 11.00 6.50 4.00 6.60 6.80 11.00 8.50
3 Butyl Methacrylate 4.50 4.00 1.30 0.00 2.70 2.50 2.30 1.50 2.00
4 Glycidyl Methacrylate 9.00 15.00 21.20 21.20 21.20 21.20 34.00 24.00 11.50
5 Hydroxy ethyl acrylate 0.00 0.00 0.00 12.80 0.00 0.00 9.40 0.00 0.00
6 Hydroxyethyl methacrylate 6.50 7.50 8.50 0.00 8.60 8.70 0.00 9.00 6.30
7 Tertiary butyl perbenzoate 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00
8 Cellosolve acetate 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
9 o-XYLENE 14.45 14.45 14.45 14.45 14.45 14.45 14.45 14.45 14.45
10 BUTYL ACETATE 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00
11 Cycloaliphatic epoxy resin 10 5 0 0 0 0 5 5 5
Part B EXPERIMENTS: (modification with siloxane oligomer)
12 Dow Corning DC 3074 24.5 24.5 24.5 24.5 24.5 24.5 10.5 17.5 31.5
13 TYZOR TPT 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05
14 ISOBUTANOL 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5
15 TOTAL 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00
Part- C : Physical and performance properties
1 EEW (g/eq.) of Resin 665 670 670 670 670 670 350 470 800
2 OH value (mg KOH/g) of Acrylic Resin 84 84 84 142 96 86 86 86 86
3 Tg °C 15 15 15 10 25 30 15 15 15
4 % Solids 70 70 70 70 70 70 70 70 70
5 % Siloxane 35 35 35 35 35 35 15 25 45
6 Film appearance (visual) Clear, glossy Clear, glossy Clear, glossy Clear, glossy Clear, glossy Clear, glossy Clear, glossy Clear, glossy Clear, glossy
7 Adhesion (using cross-cut adhesion test) Pass Pass Fails Fails Fails Fails Fails Pass Pass
8 Flexibility (Using conical mandrel test) Pass Pass Fails Fails Fails Fails Fails Pass Pass

Table 4: Experimental details of different compositions
EXPT NO 1 2 3 4 5 6 7 8 9
Base Material
Epoxy polysiloxane Resin
(These Expt nos. shows varying % resin blend of Example 3 resin of Table 1 above) 81.46 71.46 76.46 73.53 73.53 73.53 73.53 73.53 74
Flow & levelling Additive 0.5
Air release Additive 0.42 0.42 0.42 0.65 0.65 0.65 0.65 0.65 0.2
Solvent-A 4.74 4.74 4.26 4.96 4.83 3.79
Solvent-B 6.67 6.47 6.47 5.11 5.48 5.48 5.48 5.48 6
Catalyst 0.42 0.42 0.42 0.39 0.39 1 1 1 1
Adhesion Promoter –A (Trimethoxy silane) 1
Adhesion Promoter & Coupling agent –B (Methoxyfunctional methyl polysiloxane.) 0.28 0.28 0.28 1 1 1 1 1
Silicon intermediate 10 5 2.87 2.87 2.87 2.87
Hardener
Hardener -Amino silane 10.75 10.75 10.75 9.71 9.71 9.71 9.71 0 0
Silicon intermediate
Hardener solution - Amino silane with Silicon intermediate 12.71 12.71
Accelerator
Accelerator Solution - Organic titanate 0.2 0.2 1.63 2 1.5 0.8 0.8 0.8
Total 100 100 100 100 100 100 100 100 100

Table 5: Performance properties of different experiments
EXPT NO 1 2 3 4 5 6 7 8 9
Finish, IS 101: part 3/Sec. 4
Smooth Poor Smooth but with few bits Smooth, Free of bits Smooth, Free of bits Smooth, Free of bits Excellent Excellent Excellent
Nail Hardness Poor Poor Improved but Poor Good Poor Excellent Excellent Excellent Excellent
Adhesion, ASTM D3359 Poor Poor Poor Improved but Poor Improved but Poor Passes Passes Passes Passes
Salt Spray, ASTM B 117 Not done Not done Not done Not done Not done Not done Passes Passes Passes
CASS, ASTM B368 Not done Not done Not done Not done Not done Not done Passes Passes Passes
Storage Stability, :
ASTM D 1849 – 95 Not done Not done Not done Not done Not done Not done Fails Passes Passes
Further line of action To improve adhesion and surface hardness Silicon intermediate & Accelerator used. Observed bits on panel .
For avoiding bitty finish, tried solution of accelerator in solvent & % optimization of polysiloxane resin. In order to improve finish, solvent combination and defoamer dose modified. To improve adhesion, adhesion promotor and coupling agent doses increased along with reduced silicon intermediate dose. To further improve adhesion, alternate adhesion promoter tried along with increased accelerator. To improve adhesion, catalyst dose increased. Stability found poor after 15 days (Discoloration & high viscosity pick-up). To improve stability, accelerator dosage reduced. Stability found poor after 15 days (Discoloration & major viscosity pick-up.)
Due to poor stability of Base, silicon intermediate kept along with hardener. All properties are ok but flow and levelling needs further improvement.
To improve flow and levelling properties, additive used. All properties found to be satisfactory.

It was thus surprisingly found from the results of the above tables that only when the raw material formulation based on the select level of resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin having select EEW levels, when employed together with select levels of catalyst/ accelerator and silicon intermediate, and more preferably, when the hardener involves a combination of amino silicone & silicone intermediate, the formulation then appears to pass both storage stability and corrosion resistant tests.
Storage stability is the stability of the coating composition when stored at temperature of 55 ± 2 °C for 15 days. The coating composition is said to be stable when there is no phase separation, precipitation, viscosity pick up and performance parameter are same as that of initial performance.
Experiments are conducted to look for selective levels of epoxy equivalent and silicon content of Polysiloxane resin Table-6 to enable the desired attributes. Table 6 summarizes the experiments designed to reach to such select polysiloxane resin and the siloxane content therein.
Table 6: Experiments with varying epoxy equivalent of Polysiloxane resin
EXPT NO 1 2 3 4
Base Material
Epoxy Polysiloxane Resin,
EEW 300-400 with 10-20 % silicon content 75
Epoxy polysiloxane Resin
EEW 400-500 with 20-30 % silicon content 74
Epoxy polysiloxane Resin
EEW 500-700 with 30-40 % silicon content 74
Epoxy polysiloxane Resin
EEW 700- 900 with 40-50 % silicon content 76.46
Flow & levelling Additive 0.3 0.5
Air release Additive 0.42 0.42 0.2 0.42
Solvent-A 3.90 4.10 3.79 3.35
Solvent-B 6.28 7.38 6 6.07
Catalyst 0.42 0.42 1 0.42
Adhesion Promoter -A
Adhesion Promoter & Coupling agent -B 0.28 0.28 1 0.28
Silicon intermediate
Hardener
Hardener -Amino silane 0
Silicon intermediate
Hardener solution - Amino silane with Silicon intermediate 13.50 12.90
12.71
12.40
Accelerator
Accelerator Solution - Organic titanate 0.2 0.2 0.8 0.6
Total 100 100 100 100
Results
Finish, IS 101: part 3/Sec. 4 Satisfactory Satisfactory Excellent Satisfactory
Nail Hardness Poor Poor Excellent Poor
Adhesion, ASTM D3359 Poor Poor Passes Poor
Salt Spray, ASTM B 117 Not done Not done Passes Not done
CASS, ASTM B368 Not done Not done Passes Not done
Storage Stability, : ASTM D 1849 – 95 Not done Not done Passes Not done
Inference All properties found to be satisfactory

The acrylic epoxy polysiloxane as one base component is thus cured with an aminosilane, and silicon resin that is accelerated/catalyzed by organic titanate. This unique formulation helps the coating to be baked for rapid curing.

It is thus possible by way of the present advancement to provide for a polysiloxane clear coating formulation/composition having solid content ˜70% comprising the following:

i) resin blend including 5-9% epoxy resin/s, and, siloxane oligomer grafted glycidyl functional acrylic resin, said acrylic resin comprising a reaction product of hydroxyl functional base acrylic resin having -OH value in the range of 50 to 150 mg KOH/g and silanol and alkoxy functional organosiloxane resin, as a liquid base component preferably having epoxy equivalent weight in the range of 500 to 700 g/eq., solid content ~70% as a liquid base component having viscosity on gardener scale of T V at temperatures of 25 ?C (60 to 85% by weight of the resin composition)
ii) Cured with hardener selected from selected from amines, aminosilanes, blocked aminosilanes, silicone resins including organosiloxane intermediates/oligomers, and combinations thereof.
iii) Accelerator selected from Dibutyltin dilaurate (DBTDL) and Organic titanates.

wherein said coating /film is configured to provide a high durable corrosion resistance coating over Ni-Cr plated and PVD faucet, that is also preferably storage stable.
Said organosiloxane based acrylic resin have acrylic polyol component based on hydroxy acrylate monomer, with said acrylic polyol and curing components are operated at phr level 80- 110.

According to another aspect of the present invention there is provided said curing component that is further blended with liquid silicon resin (>99% solids) that dries as a result of chemical reaction / presence of catalyst / hydrolysis to a solid resin and offer desired hardness.

Preferably said accelerator is DBTDL / Organic titanates that improves crosslinking as well as improve efficacy of reaction, scratch resistance, hardness and adhesion with the substrates.

Advantageously said coating/film forming composition can be applied using conventional techniques such as spray, baking, brush, dip coating etc. at DFT ranging from 5 µm to 25 µm thickness, and provides for the following:
low surface energy (<35 mN/m) over Ni-Cr plated or PVD surface;
high contact angle (>80 degree) results water droplet easily spreads out more over Ni-Cr plated faucet or PVD surface;
flexibility as measured by passing of the conical mandrel bend test (1/4 inch);
high impact resistance as measured by passing 7.1 Joule over Ni-Cr plated surface;
Taber abrasion resistance as measured by passing <50 mg (500 cycles/1kg @ CS 10 wheel);
scratch resistance as measured by passing > 0.7kg;
high corrosion resistance in copper accelerated acetic acid salt spray (CASS); ASTM B368 (>200 hrs.) over Ni-Cr plated and PVD faucet;
salt Spray resistance; ASTM B 117 (>500 hrs.) over Ni-Cr plated and PVD faucet;
acid and alkali resistance properties over Ni-Cr plated and PVD surface;
dries by a combination of solvent evaporation and chemical curing reaction between the base component and curing agent;
resulting clear coating offers high durability and flexibility to the base surface such as Ni-Cr or Cu-Ni-Cr.