Claims:We Claim:

1. A hybrid binder base formulation suitable for coating hot metal surfaces comprising
a) Acrylic polyol 2-10 wt.% having hydroxyl value in the range of 60 to 100 mg KOH/g.
b) 16-28 wt.% Epoxy based acrylic polysiloxane having epoxy equivalent weight of 400 to 700 g/eq,

2. The hybrid binder base formulation suitable for coating hot metal surfaces as claimed in claim 1 that is stable for 12 months maintaining the viscosity levels of 100-170 gms on Stormer Viscometer at 30 deg.C
3. The hybrid binder base formulation as claimed in claims 1 or 2 having siloxane content preferably of less than 20% on binder formulation and involves epoxy based acrylic polysiloxane and acrylic polyol preferably in the ratio range of from 60:40 to 40:60 and most preferably in the ratio of 44.64: 55.36.

4. The hybrid binder base formulation as claimed in claims 1-3 that is solvent borne and ambient to high temperature curable with aminosilanes on 1:1 stoichiometric basis of epoxy equivalent weight of said epoxy functional acrylic siloxane on said binder soptionally, including inorganic fillers and additives.

5. The hybrid binder base formulation as claimed in claims1-4as ambient to high temperature cured coating formulation wherein said formulation comprises
a) 16-28 wt.% Epoxy based acrylic polysiloxane having epoxy equivalent weight of 400 to 700 g/eq;
b) Acrylic polyol 2-10 wt.% having hydroxyl value in the range of 60 to 100 mg KOH/g;
c) 1-2 wt.% Aminosilane at 1:1 stoichiometric basis with respect to epoxy equivalent wt. of said binders;
d) 10-20 wt.% Inorganic fillers;
e) 2-8 wt.% Additives;
f) 50-70 wt.% organic solvents.
wherein said epoxy based acrylic polysiloxane and acrylic polyol is preferably in theratio range of from 60:40 to 40:60 and most preferably in the ratio of 44.64: 55.36.

6. The hybrid binder base formulation as claimed in claims 1-5 suitable for coating hot metal surfaces in being heat resistance suitable for continuous exposure upto 200°C and intermittent exposure upto250°C.

7. The hybrid binder base formulation as claimed in claims 1-6 wherein said epoxy acrylic polysiloxane resin have molecular weights in the range of 2000-20000and Tg in the range of-30 °C to +30°C.

8. The hybrid binder base formulation as claimed in claims 1-7 wherein said acrylic polyol resin have molecular weight (Mn) of 2000 to 20000 and Tg in the range of -30°C to +30°C.

9. The hybrid binder base formulation as claimed in claims 1-8 wherein said acrylic polyol resin is comprised of acrylic monomers selected from esters of acrylic and methacrylic acid such as such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, cyclohexyl, n-octyl, 2-ethylhexyl, lauryl, isobornyl or any combinations thereof; is comprised of Hydroxyl functional monomers hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, their methacrylates or any combinations thereof; comprises Vinyl monomers including styrene, alpha-methyl styrene, para-methyl styrene, or combinations thereof; comprises carboxyl functional monomers including acrylic acid, methacrylic acid, fumaric acid, crotonic acid, itaconic acid, maleic acid, cinnamic acid; includes Epoxy functional monomers such as glycidyl methacrylate and glycidyl acrylate;
Said epoxy acrylic polysiloxane resin includes Epoxy Novolac Resin, Epoxy solvent cut resin, liquid epoxy resin based on bisphenol-A, Bisphenol F type epoxy, epoxy resin of hydrogenated Bisphenol A, and bisphenol A/F epoxy resin with monofunctional reactive diluent preferably either an aromatic epoxy, or an aliphatic or cycloaliphatic epoxy, preferred being cycloaliphatic epoxy resin, reacted under free radical polymerization with siloxane oligomers including hydroxyl functional and alkoxy functional oligomers and their combinations including methyl/propyl/phenyl functional oligomers or their combinations, in presence of thermal initiators including azobisisobutyronitrile, tertiary-butyl perbenzoate, dimethyl 2, 2'-azobis(2-methylpropionate), ditertiary butyl peroxide, dicumyl peroxide, ditertiary amylperoxide, or any combination thereof.

10. The hybrid binder base formulation as claimed in claims 1-9 that is ambient curable with aminosilane selected from aminopropyltriethoxysilane, N-ß-aminoethyl-?-aminopropyltrimethoxysilane, N-phenyl-?-aminopropyltrimethoxy-silane, and bis-?-trimethoxysilylpropylamine.

11. The hybrid binder base formulation as claimed in claims 1-10curable with curing agents selected from aliphatic amine adducts, cycloaliphatic amine adducts, aromatic amine adducts, Mannich bases, phenalkamines, polyetheramines, polyamides and polyamidoamines.

12. The hybrid binder base formulation as claimed in claims 1-11wherein saidinorganic fillers are selected from the category of hydrated magnesium silicate, hydrated aluminium silicate, amorphous silica, phyllosilicate, barium sulphate, calcium carbonate, titatnium dioxide and zinc phosphates.

13. The hybrid binder base formulation as claimed in claims 1-12 wherein said additives are selected from the category of rheological additives like absorbent aluminium phyllosilicate clay, fumed silica, organophilic phyllosilicates and ethyl cellulose nitrate, adhesion promoter like gamma-glycidoxypropyltrimethoxy -silane, gamma-glycidoxypropyltriethoxysilane and gamma-glycidoxy- propylmethyldiethoxysilane, wetting and dispersing agent, flexibiliser like hydrocarbon wax, halogenated wax, blocked isocyanates and renewable vegetable wax, catalyst like oregano tin, zinc octoate.

14. The hybrid binder base formulation as claimed in claims 1-13 wherein said organic solvents are selected from hydrocarbons, aliphatic alcohols and aliphatic esters, ketones, ethers, glycol ethers.

15. A method for manufacturing said hybrid binder base formulation as claimed in claims 1-14 comprising
(a) providing Acrylic polyol 2-10 wt.% having hydroxyl value in the range of 60 to 100 mg KOH/g;
(b) providing 16-28 wt.% Epoxy based acrylic polysiloxane having epoxy equivalent weight of 400 to 700 g/eq;
stabilizing the same in solvent, and optionally, adding thinning and tinting components to obtain therefrom said stable hybrid binder base formulation.

16. The method for manufacturing said hybrid binder base formulation as claimed in claim 15 wherein said step (a) of providing acrylic polyol is based on free radical polymerization comprises the steps of:
i) charging the monomer and initiator mix in solvent preferably into orthoxylene for digestion;
ii) adding chaser catalyst with continued stirring;
iii) cooling and filtering through 120 mesh nylon filter.

17. The method as claimed in claim 15-16 wherein said
Step (i) involves charging the monomer and initiator mix into orthoxylene for a period of 3 to 6 hours preferably 4 hours at 140-144 deg C followed by 30 minutes to 2 hours preferably 1 hour digestion;
Step (ii) involves adding chaser catalyst with continued stirring for 30 minutes to 2 hours preferably 1 hour;
Step (iii) involves cooling and filtering through 120 mesh nylon filter yielding the resin with parameters %NVM = 60 to 80 preferably 70% and Gardner viscosity= Z to Z6 preferably Z2, hydroxyl value = 60 to 100 preferably 75 mg KOH/g, acid value = 1 to 20 preferably 10 mg KOH/g with a Tg of -30 to +30 preferably 19 deg C.
18. The method as claimed in claim 15 wherein said step (b) of providing Acrylic Polysiloxane comprises the steps of:
(i) charging of cycloaliphatic epoxy resin and orthoxylene as reactive diluent and solvent respectively followed by mixture of monomers and initiator to the reactor and continuing polymerization;
(ii) condensing thus obtained epoxy functional acrylic polyol with hydroxyl functional siloxane resin at high temperature in presence of a catalyst;
(iii) cooling and adding the methoxy functional siloxane to the reactor.

19. The method as claimed in claim 18
wherein said mixture of monomers involves 2-EHA, BMA, GMA, HEMA and initiator DTAP that is added to the reactor over a period of 3 to 8 hours preferably 6 hours;
wherein said polymerization is continued for 1 to 3 hours preferably 2 hours with additional luperox DTAP is to achieve complete monomer conversion;
wherein said condensing thus obtained epoxy functional acrylic polyol with hydroxyl functional siloxane resin (Silres SY300) is at 140 to 150 °C in presence of 2-ethyl hexanoic acid as catalyst for 1 to 6 hours preferably 3 hours;
wherein said cooling and adding the methoxy functional siloxane to the reactor at 30 to 120 °C preferably 80 °C.
20. The method for the preparation of hybrid binder base formulation as claimed in claims 15-19 as ambient to high temperature cured coating formulation comprising the steps of:
(I) Providing said hybrid binder base formulation using premix tank followed by horizontal dyno mill and then thinning and tinting using mixer of RPM 40- 50 with a finish of 6+ on Hegmann Gauge;
(II) preparing the hardener in a mixer separately as a solution in xylene under nitrogen blanket;
(III) mixing base and hardener in ratio 91.65:8.35 by weight providing said coating formulation.

Dated this the 19th day of March, 2020 Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)
IN/PA-199
, Description:Field of the Invention
Present invention relates to heat resistant hybrid binder base formulation/composition free of polysilazane, organosilicone phosphate, alkali metal silicate, inorganic silicic acid esters, titanate.

Background of the invention
Coating emulsions obtained by emulsion polymerizing radical polymerizablevinyl monomers, as typified by acrylic-resin systems, have been widely used as the base component of coating compositions because they have good film formability and chemical resistance. Such coating compositions, however, suffer from the essential lack of water resistance and fire resistance.
On the other hand, silicone resins obtained by hydrolysis and condensation of silane compounds attract attention as coating compositions because they are capable of forming films having high hardness, weather resistance, water resistance, heat resistance and water repellency. Nevertheless, the silicone resins are not only inferior in film formability, alkali resistance, and film flexibility, but also lack shelf stability because silanol/alkoxy groups have high condensation activity.
Specialty polymers viz. polysilazane and organosilicone phosphate resins generally have high cost. Primarily inorganic silicic acid esters such as TEOS, TMOS, Titanates such as Titanium Ethoxide and their sols are used as binders which require strong acid catalyst such as HCl etc. and often involve high temperature curing and may give brittle films. Other products as stated above uses 25 to 70% siloxane base material.
Also alkali metal silicates along with inorganic pigments such as Barium titanate are used and does not mention any direct application on hot metal surface.
Countless attempts have been reported to obtain the best out of a combination of the two namely acrylics and silicone resins in terms of fire protection or corrosion resistance and stability of the coating. Few of the related prior arts are presented hereunder.

WO2012101042A1 relates to a composition that can be used as a coating and that can protect a substrate coated with this composition from high heat. The composition comprises: a polysulfide, an epoxy resin, a compound selected from compounds having a secondary and/or a tertiary amine group, and compounds having an amide group, a polysiloxane, and fibres.
In GB2159522 an ablative coating system is disclosed comprising a reactive mixture of epoxy and polysulfide resins, an amine curing agent, inorganic materials, and carbonaceous pre-ox fibers. This coating can provide thermal protection in a high temperature, erosive environment. In US4965296 a fire retardant coating materials is disclosed that includes a fluid intumescent material and conductive particles of various sizes.
EP1593699 B1 provides for synthetic resins and processes for making the same and more particularly, relates to aliphatic and aromatic two part acrylics, and epoxies having improved adhesion, chemical resistance, UV stability, and decreased shrinkage properties and to methods of making the same and scopes under the claims as below.
A silicone modified epoxy resin comprising: a first component which includes at least one polyol prepolymer chain extender which comprises: at least one amine; at least one epoxy functional silicone; and a second component which comprises at least one epoxy resin.
US4446259 teaches an ambient curing composition of the coating comprises (a) an acrylic polymer containing glycidyl groups and (b) a crosslinkable polysiloxane having attached to the silicone atoms of its backbone alkyl groups, phenyl groups and hydroxyl groups; providing a finish that is durable, weatherable and heat resistant and is particularly useful for coating pipes, tanks, vessels and stacks of plants and refineries that are subjected to weathering, chemicals and heat.
US6281321B1 relates to a curable coating composition having a binder comprising a compound or polymer (A) containing at least one primary or secondary amine group, a compound or polymer (B) containing at least one ethylenically unsaturated double bond activated by an adjacent electron-withdrawing group, and a polymer (C) containing at least two silicon-bonded alkoxy groups. Either (A) or (B) contains at least one silicon-bonded alkoxy group in its molecule. The coating is capable of curing at ambient temperature and humidity both by hydrolysis and condensation of the Si—O—C bonds of the polyorganosiloxane (C) and of the aminoalkylsilane (A) and by Michael-type addition reaction of the amine group of the aminoalkylsilane (A) with the activated ethylenically unsaturated double bonds of (B).
US8168738B2 disclosed low temperature, moisture curable coating compositions, related coated substrates, and methods for coating a substrate. The coating compositions include an ungelled, secondary amine-containing Michael addition reaction product of reactants including a compound comprising more than one site of ethylenic unsaturation, and an amino functional silane.
US8742012B2 is directed to a thermosetting film-forming composition comprising a polytrialkanolamine reacted with a crosslinking agent composition. The composition forms a three-dimensional crosslinked network having atrane-containing linkages.
US 2007/0213492A1 disclosed coating compositions that include both (a) an alkoxy-functional and/or silanol-functional silicone; and (b) an epoxy-functional silicone wherein the alkoxy-functional and/or silanol-functional silicone comprises a compound represented by the general formula:
R2-O-[Si (R1R1)-O]n R2, wherein:
(a) each R, which may be same or different, is selected from the group consisting of a hydroxy group, an alkyl group having up to six carbon atoms, an aryl group having up to six carbon atoms, and an alkoxy group having up to six carbon atoms;
(b) each R, which may be the same or different, is selected from the group consisting of hydrogen, an alkyl group having up to six carbon atoms, and an aryl group having up to six carbon atoms; and
(c) ‘n’ is selected so that the silicone has a weight average molecular weight in the range of from 400 to 10,000; wherein the first component is acting like a polyol which may react with the epoxy of the other component
WO2006031891A2 describes fast-curing modified siloxane compositions comprise; (1) an alkoxy- or silanol-functional silicone intermediate, (2) at least one amine reactive ingredient selected from the group consisting of acetoacetate-functional ingredients, acrylate-functional ingredients, and mixtures thereof, (3) an epoxy-functional ingredient, (4) a curing agent selected from the group consisting of amines, aminosilanes, ketimines, aldimines and mixtures thereof, and (5) water. Other ingredients useful in forming fast-curing modified siloxane compositions of this advancement include silanes, organometallic catalysts, solvents, pigments, fillers and modifying agents. The above-identified ingredients are combined and reacted to form a fully cured protective film comprising a cross-linked enamine polysiloxane and/or acrylate polysiloxane chemical structure in a reduced amount of time when compared to conventional epoxy siloxane compositions.
WO2014150332A1 is directed to a resin composition comprising (1) anepoxysilicone resin; (2) optionally, an epoxyfluorosilicone resin and (3) a fluorinated (ornon-fluorinated) silane-modified polyacrylic resin. This advancement is also directed to a coating composition comprising the resin and a curing agent, for use as a coating composition providing improved weatherability, chemical resistance, corrosion resistance, and abrasion resistance. The coating may additionally have pigments, fillers, defoamers, deaerators, solvent, flow and leveling agents.
RU2493305 discloses a two step procedure for coating. First coated with oligo(aminopropyl)ethoxysiloxane, dried and then heat treated – further treated with glycidol and finally with N,N-bis(1,2-dihydroxypropyl)aminoalkyl to yield the coating.
RU2458089 teaches room temperature fast-curable organopolysiloxane composition contains: (A) diorganopolysiloxane with a hydroxy group on both ends and/or a hydrolysable group, (B) alkenoxysilane of formula: R1?x-Si(O-CR2=CR3R4)4-x where R1 and R2 are independently an unsubstituted or substituted univalent hydrocarbon group; R3 and R4 are independently a hydrogen atom or a substituted or unsubstituted univalent hydrocarbon group; under the condition that R2 and R3 can together represent an alicyclic hydrocarbon group containing a C=C double bond in the formula given above, with carbon atoms, with R2 and R3 bonded thereto, x equals 0 or 1; or partial hydrolysate thereof, (C) aminosilane of formula: R5?y-Si(NHR6)4.y, where R5 is a substituted or unsubstituted univalent hydrocarbon group; R6 is a substituted or unsubstituted univalent hydrocarbon group; and y equals 0 or 1; or partial hydrolysate thereof, and (D) a curing agent.
The method of curing a room temperature fast-curable organopolysiloxane composition involving coating a substrate with a first portion of the composition containing components (A), (B) and (D), coating another substrate with a second portion of the composition containing components (A), (C) and optionally (D), and binding the substrates by curing the first portion of the composition together with the second portion of the composition obtaining a room temperature fast-curable organopolysiloxane composition capable of fast and complete curing
US10138381B2 refers to a silicon based coating composition for a wide range of surfaces, which composition is formed from a mixture of constituents comprising appropriate portions of silazane, siloxane, and silane, and optionally organic solvent and additives, and the composition results in a coating having a thickness between 0.4 mil and 1.5 mil, a hardness of 4-9H and an endurance to continuous temperature above 1600° F.
Synthesis, characterization and development of high performance siloxane-modified epoxy paints Progress in Organic Coatings, Volume 54, Issue 3, 1 November 2005, Pages 248–255 teaches Diglycidyl ether of bisphenol A (DGEBA) epoxy was modified with hydroxyl-terminated poly dimethyl siloxane (HPDMS), through ring opening addition polymerization reaction. DGEBA and siloxane-modified epoxy resin (ESR), were subjected to paint formulation with the help of TiO2, Fe2O3 and lemon chrome pigments. The formulated paint systems were cured at room temperature with polyamide (PA) used as curing agent. The DGEBA–PA and siloxane-modified epoxy–polyamide (ESR–PA) paints were applied on mild steel strips. The effect of siloxane incorporation and the role of PA as a curing agent on the coating properties of these paint systems were also investigated along with physico-mechanical and anticorrosive performance. The ESR–PA system was found to exhibit good thermal and corrosion resistance performance.
Preparation and characterization of heat-resistant interpenetrating polymer network (IPN) Progress in Organic Coatings, Volume 59, Issue 1, 2 April 2007, Pages 21-27 reported Interpenetrating polymer network (IPN) as a novel type of polymer hybrid possessing physicochemical properties suitable for high performance coatings. Heat-resistant IPN was prepared from immiscible resins, epoxy and silicones using a cross-linking agent and a catalyst. The heat resistance property and corrosion behaviour of the IPNs were also determined. It was different from those of the individual resins. Silicone microdomains could be seen uniformly distributed in epoxy regions. Corrosion resistance property of the IPNs was evaluated by salt spray and impedance measurements. The IPNs withstood longer durations in the salt spray chamber.
PCI magazine teaches Adding Value to Industrial Coatings by Using Epoxy Functional Silicone Resins October 1, 2004 reported that coatings prepared by reaction of the epoxy-functional silicone polymer with amino-functional silane, amino-functional glycol, acrylic and acid-functional acrylics were evaluated for hydrolysis resistance. The boiling water test revealed that coatings prepared using the amino silanes as the primary method of crosslinking failed after 4 hours. The glycol-modified amino hardener (Formulations 1-3) and the acid functional acrylic hardener passed.
Using the Si-O strength: European Coatings Journal, Issue 06/2007 Page 54 discloses the superiority of epoxy-amine-siloxanes and acrylic-amine-siloxanes compared with an epoxy/polyamine adduct and a 2K aliphatic polyurethane.
EP1000980B1 relates to a curable composition modified with a vinyl polymer having at least one crosslinkable silyl group. More particularly, it relates to a curable composition which when blended with an epoxy resin, gives a composition capable of firmly adhering to various substrates and showing elastic properties after curing and useful, in particular, as an elastic adhesive and to a curable composition which when blended with a polyether polymer having at least one crosslinkable silyl group, gives a composition showing, after curing, a high elongation and good weathering resistance.
Furthermore, EP-A0469613 describes the preparation of an organopolysiloxane/ acrylate ester emulsion which is prepared by forming a water-based emulsion of an alkenyl-containing organopolysiloxane and copolymerizing the emulsion in an addition reaction with an acrylate monomer. The use of the resultant polymer as a release coating is also described.
In view of the foregoing it is apparent that none of the documents referred to above provide any clear guidance/directions on how a composition free of polysilazane and organosilicone phosphate resins, can be obtained that would show(i)high heat resistance capability, (ii) good binder stability, (iii) low temperature curing, and (iv) formation of a uniform cured film having good characteristics including mar resistance, weather resistance, and chemical resistance with less than 20% polysiloxane, and would also be applicable directly on hot metal surface at 150°C.
Objects of the Invention
The prime objective of the present invention is to provide a hybrid binder based coating formulation/composition containing <20% siloxane content providing heat resistant coating that can withstand continuous exposure to 200°C and intermittent exposure to 250°C.
Another objective of the present invention is to provide the said coating formulation/composition which can be applied directly on hot metal surface at 150°C.
Another objective of the present invention is to provide for said coating formulation/composition which will be ambient curing.
Another objective of the present invention is to provide for said coating formulation/composition which will be free of specialty polymers viz. polysilazane and organosilicone phosphate resins.
Another objective of the present invention is to provide for said coating formulation/composition devoid of inorganic silicic acid ester, such as TEOS, TMOS, Titanates such as Titanium Ethoxide and their sols.
Another objective of the present invention is to provide the said coating formulation/composition providing coating with excellent corrosion resistance, good mechanical properties like abrasion resistance, flexibility, hardness and excellent solvent resistance.
Still another objective of the present invention is to provide for said coating formulation/composition which can be applied on manually/ power tool cleaned surface.
Summary of the Invention
The primary aspect of the present invention is directed to provide a hybrid binder base formulation suitable for coating hot metal surfaces comprising
a) Acrylic polyol 2-10 wt.% having hydroxyl value in the range of 60 to 100 mg KOH/g.
b) 16-28 wt.% Epoxy based acrylic polysiloxane having epoxy equivalent weight of 400 to 700 g/eq.

Another aspect of the present invention is directed to provide said hybrid binder base formulation suitable for coating hot metal surfaces which is stable for 12 monthsby maintaining viscosity levels of 100-170 gms on Stormer Viscometer at 30 deg.C

Yet another aspect of the present invention is directed to provide said hybrid binder base formulation having siloxane content preferably of less than 20% on binder formulation and involves epoxy based acrylic polysiloxane and acrylic polyol preferably in the ratio range of from 60:40 to 40:60 and most preferably in the ratio of 44.64: 55.36.

A further aspect of the present invention is directed to provide said hybrid binder base formulation that is solvent borne and ambient to high temperature curable with aminosilanes on 1:1 stoichiometric basis of epoxy equivalent weight of said epoxy functional acrylic siloxane on said binder optionally, including inorganic fillers and additives.

Still further aspect of the present invention is directed to provide said hybrid binder base formulation as ambient to high temperature cured coating formulation wherein said formulation comprises
a) 16-28 wt.% Epoxy based acrylic polysiloxane having epoxy equivalent weight of 400 to 700 g/eq;
b) Acrylic polyol 2-10 wt.% having hydroxyl value in the range of 60 to 100 mg KOH/g;
c) 1-2 wt.% Aminosilane at 1:1 stoichiometric basis with respect to epoxy equivalent wt. of said binders;
d) 10-20 wt.% Inorganic fillers;
e) 2-8 wt.% Additives;
f) 50-70 wt.% organic solvents;
wherein said epoxy based acrylic polysiloxane and acrylic polyol is preferably in the ratio range of from 60:40 to 40:60 and most preferably in the ratio of 44.64: 55.36.

Another aspect of the present invention is directed to provide said hybrid binder base formulation suitable for coating hot metal surfaces in being heat resistance suitable for continuous exposure upto 200°C and intermittent exposure upto250°C.

Another aspect of the present invention is directed to provide said hybrid binder base formulation wherein said epoxy acrylic polysiloxane resin have molecular weights in the range of 2000-20000 and Tg in the range of-30°C to +30°C.

Yet another aspect of the present invention is directed to provide said hybrid binder base formulation wherein said acrylic polyol resin have molecular weight (Mn) of 2000 to 20000 and Tg in the range of -30°C to +30°C.

Another aspect of the present invention is directed to providesaidhybrid binder base formulation wherein said acrylic polyol resin is comprised of acrylic monomers selected from esters of acrylic and methacrylic acid such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, cyclohexyl, n-octyl, 2-ethylhexyl, lauryl, isobornyl or any combinations thereof. Hydroxyl functional monomers such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, their methacrylates or any combinations thereof may also be used. Vinyl monomers such as styrene, alpha-methyl styrene, para-methyl styrene, or any combination thereof may also be used. Carboxyl functional monomers such as acrylic acid, methacrylic acid, fumaric acid, crotonic acid, itaconic acid, maleic acid, cinnamic acid may be used. Epoxy functional monomers such as glycidyl methacrylate and glycidyl acrylate can be used.
The epoxy resin of the present invention includes Epoxy Novolac Resin, Epoxy solvent cut resin, liquid epoxy resin based on bisphenol-A, Bisphenol F type epoxy, epoxy resin of hydrogenated Bisphenol A, and bisphenol A/F epoxy resin with monofunctional reactive diluent preferably either an aromatic epoxy, or an aliphatic or cycloaliphatic epoxy. Cycloaliphatic epoxy resin is preferred.
The siloxane oligomers used for the synthesis include hydroxyl functional and alkoxy functional oligomers and their combinations including methyl/propyl/phenyl functional oligomers or their combinations, and polymerization with epoxy resin is carried out using free radical polymerization thermal initiators. The initiators inlcuding may be azobisisobutyronitrile, tertiary-butyl perbenzoate, dimethyl 2, 2'-azobis(2-methylpropionate), ditertiary butyl peroxide, dicumyl peroxide, ditertiary amylperoxide, or any combination thereof.

Another aspect of the present invention is directed to provide saidhybrid binder base formulation that is ambient curable with aminosilane selected from aminopropyltriethoxysilane, N-ß-aminoethyl-?-aminopropyltrimethoxysilane, N-phenyl-?-aminopropyltrimethoxy-silane, and bis-?-trimethoxysilylpropylamine.

Yet another aspect of the present invention is directed to provide said hybrid binder base formulation wherein other curing agents may also be selected from aliphatic amine adducts, cycloaliphatic amine adducts, aromatic amine adducts, Mannich bases, phenalkamines, polyetheramines, polyamides and polyamidoamines.

Another aspect of the present invention is directed to provide said hybrid binder base formulation wherein saidinorganic fillers are selected from the category of hydrated magnesium silicate, hydrated aluminium silicate, amorphous silica, phyllosilicate, barium sulphate, calcium carbonate, titatnium dioxide and zinc phosphates.

Further aspect of the present invention is directed to provide said hybrid binder base formulation wherein said additives are selected from the category of rheological additives like absorbent aluminium phyllosilicate clay, fumed silica, organophilic phyllosilicates and ethyl cellulose nitrate, adhesion promoter like gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropyltriethoxysilane and gamma-glycidoxypropylmethyl-diethoxysilane, wetting and dispersing agent, flexibiliser like hydrocarbon wax, halogenated wax, blocked isocyanates and renewable vegetable wax, catalyst like oregano tin, zinc octoate.

Still further aspect of the present invention is directed to provide said hybrid binder base formulation wherein said organic solvents are selected from hydrocarbons, aliphatic alcohols and aliphatic esters, ketones, ethers, glycol ethers.

Another aspect of the present invention is directed to provide a method for manufacturing said hybrid binder base formulation comprising:
(a) providing Acrylic polyol 2-10 wt.% having hydroxyl value in the range of 60 to 100 mg KOH/g;
(b) providing 16-28 wt.% Epoxy based acrylic polysiloxane having epoxy equivalent weight of 400 to 700 g/eq;
stabilizing the same in solvent, and optionally, adding thinning and tinting components to obtain therefrom said stable hybrid binder base formulation.

Yet another aspect of the present invention is directed to provide saidmethod for manufacturing said hybrid binder base formulation wherein said step (a) of providing acrylic polyol is based on free radical polymerization comprises the steps of:
i) charging the monomer and initiator mix in solvent preferably into orthoxylene for digestion;
ii) adding chaser catalyst with continued stirring;
iii) cooling and filtering through 120 mesh nylon filter.

Another aspect of the present invention is directed to provide saidmethod wherein said Step (i) involves charging the monomer and initiator mix into orthoxylene for a period of 3 to 6 hours preferably 4 hours at 140-144 deg C followed by 30 minutes to 2 hours preferably 1 hour digestion;
Step (ii) involves adding chaser catalyst with continued stirring for 30 minutes to 2 hours preferably 1 hour
Step (iii) involves cooling and filtering through 120 mesh nylon filter yielding the resin with parameters %NVM = 60 to 80 preferably 70% and Gardner viscosity = Z to Z6 preferably Z2, hydroxyl value = 60 to 100 preferably 75 mg KOH/g, acid value = 1 to 20 preferably 10 mg KOH/g with a Tg of -30 to +30 preferably 19 deg C.

Still another aspect of the present invention is directed to provide said method wherein said step (b) of providing Acrylic Polysiloxane comprises the steps of:
(i) charging of cycloaliphatic epoxy resin and orthoxyleneas reactive diluent and solvent respectively followed by mixture of monomers and initiator to the reactor and continuing polymerization;
(ii) condensing thus obtained epoxy functional acrylic polyol with hydroxyl functional siloxane resin at high temperature in presence of a catalyst;
(iii) cooling and adding the methoxy functional siloxane to the reactor.
Further aspect of the present invention is directed to provide saidwherein said mixture of monomers involves 2-EHA, BMA, GMA, HEMA and initiator DTAP that is added to the reactor over a period of 3 to 8 hours preferably 6 hours;
wherein said continuing polymerization for 1 to 3 hours preferably 2 hours with additional luperox DTAP is to achieve complete monomer conversion;
wherein said condensing thus obtained epoxy functional acrylic polyol with hydroxyl functional siloxane resin (Silres SY300) is at 140 to 150 °C in presence of 2-ethyl hexanoic acid as catalyst for 1 to 6 hours preferably 3 hours;
wherein said cooling and adding the methoxy functional siloxane to the reactor at 30 to 120 °C preferably 80 °C.
Still furtheraspect of the present invention is directed to provide said method for the preparation of hybrid binder base formulation as ambient to high temperature cured coating formulation comprising the steps of:
(I) Providing said hybrid binder base formulation using premix tank followed by horizontal dyno mill and then thinning and tinting using mixer of RPM 40- 50 with a finish of 6+ on Hegmann Gauge;
(II) preparing the hardener in a mixer separately as a solution in xylene under nitrogen blanket;
(III) mixing base and hardener in ratio 91.65:8.35 by weight providing the said coating formulation.
Detailed description of the invention
As mentioned hereinbefore, the present invention provides for ambient curing hybrid binder base formulation/composition enabling heat resistance to upto 200°C with continuous exposure and 250°C for intermittent exposure, which is also highly corrosion resistance with good mechanical properties like abrasion resistance, flexibility, hardness etc. Additionally, said hybrid curable formulation comprises less than 20%siloxane content and is free of polysilazane, organosilicone phosphate, alkali metal silicate, inorganic silicic acid esters, titanate.
According to an embodiment of the present invention is provided hybrid coating composition comprising:
a) Acrylic polysiloxane with epoxy functionality having an epoxy equivalent weight of 400 to 700 g/eq (16-28 % by weight)
b) Acrylic polyol having a hydroxyl value of 60 to 100 mg KOH/g (2-10% by weight)
c) Aminosilane on a 1:1 stoichiometric basis (1-2% by weight)
d) Inorganic fillers (10-20% by weight)
e) Additives (2 to 8% by weight)
f) Organic solvents (50 to 70% by weight).
According to another embodiment said coating composition comprisessiloxane content of <20% by weight; acrylic polysiloxane resin of molecular weight 2000-20000, Tg-30°C to +30°C and an acrylic polyol resin of molecular weight Mn 2000 to 20000,Tg-30°C to +30 °C;
According to yet another embodiment of the said hybrid coating composition comprises an aminosilane for use in the silane package including but not limited to aminopropyltriethoxysilane, N-ß-aminoethyl-?-aminopropyltrimethoxysilane, N-phenyl-?-aminopropyltrimethoxysilane, and bis-?-trimethoxysilylpropylamine and inorganic fillers selected from the category of hydrated magnesium silicate, hydrated aluminium silicate, amorphous silica, phyllosilicate, barium sulphate, calcium carbonate, titatnium dioxide and zinc phosphates.
According to yet another embodiment of thepresent invention wherein additives for the said hybrid coatingcomposition is selected fromthe category of rheological additives like absorbent aluminium phyllosilicate clay, fumed silica, organophilic phyllosilicates and ethyl cellulose nitrate, adhesion promoter like gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropyltriethoxysilane and gamma-glycidoxypropylmethyldiethoxysilane, wetting and dispersing agent, flexibiliser like hydrocarbon wax, halogenated wax, blocked isocyanates and renewable vegetable wax, catalyst like oregano tin, zinc octoate.
According to yet another embodiment of the present invention wherein said composition is organic solvent based selected from the range of hydrocarbons, aliphatic alcohols and aliphatic esters, ketones, ethers, glycol ethers.
Example 1:
Synthesis of Acrylic polyol
The acrylic polyol is synthesized using free radical polymerization in orthoxylene in a 4 neck reactor fitted with a condenser. The wt% of different ingredients for the synthesis of polyol is given in Table 1.
Table 1: Formulation of the Acrylic polyol
Sr. No. Monomer Composition
1 Styrene 5
2 MMA 26
3 Butyl acrylate 26
4 Hydroxyethyl methacrylate 12
5 Methacrylic acid 1
6 Tertiary butyl per benzoate(initiation) 3
7 Tertiary butyl per benzoate(digestion) 0.5
8 Ortho xylene 26.5
Total 100
The monomer and initiator mix is added into orthoxylene for a period of 4 hours at 140-144 deg C after which 1 hour digestion is allowed. After 1 hour digestion, chaser catalyst addition is done and the batch is continued for 1 hour more. The batch is then cooled and filtered using 120 mesh nylon filter. The resin parameters are as follows: %NVM = 70% and Gardner viscosity = Z2, hydroxyl value = 75 mg KOH/g, acid value = 10 mg KOH/g with a Tg of 19 deg C.
The acrylic polyol with hydroxyl value in the range of 60-100 mg KOH/g is found to be most suitable to provide for a stable base formulation.
Example 2: Synthesis of Acrylic Polysiloxane
A 4 neck glass reactor with a condenser and Dean Stark apparatus is taken. Orthoxylene is filled in the Dean Stark apparatus. The acrylic polysiloxane resin was made in two stages. In first stage, epoxy functional acrylic polyol was prepared through solution polymerization technique. Cycloaliphatic epoxy resin and orthoxylene was charged to the reactor as reactive diluent and solvent respectively. The mixture of monomers 2-EHA, BMA, GMA, HEMA and initiator DTAP was charged to the reactor over a period of 6 hours. The polymerization was continued for 2 hours during which additional luperox DTAP was charged in order to achieve the complete monomer conversion. In the second stage, the condensation reaction of epoxy functional acrylic polyol prepared in the first stage and hydroxyl functional siloxane resin (Silres SY300) was carried out at 140 to 150 °C in presence of 2-ethyl hexanoic acid as catalyst. The condensation reaction is continued for 3 hours. Water of reaction is collected in the Dean Stark tube. Cooling is applied and the methoxy functional siloxane is added to the reactor at 80 °C. The Resin formulation is shown in Table 2and its physical properties are given below the table.
Table 2: Formulation of the Acrylic Polysiloxane resin
S.N. Monomer Composition
1 2-Ethyl Hexyl Acrylate (2-EHA) 6
2 Hydro ethyl methacrylate (HEMA) 2.5
3 Glycidyl methacrylate (GMA) 14
4 Di-tertiary amyl peroxide (DTAP)(initiation) 0.5
5 Di-tertiary amyl peroxide (for complete conversion) 0.3
6 Cycloaliphatic epoxy resin with EEW of 240 g/equ. 24.4
7 Orthoxylene 25
8 2-ethyl hexanoic acid 0.3
9 Hydroxy functional siloxane with OH value = 5% 22
10 Methoxy functional phenyl methyl siloxane with methoxy content = 16% 5
Total 100
The batch is then cooled and filtered using 120 mesh nylon filter. The resin parameters are as follows: %NVM = 75% and Gardner viscosity = U-V, EEW = 650 g/eq. and a siloxane content of 36%.
The following Table 3 exemplifies coating in accordance with the present invention for hot metal surface having desired heat resistance and applicability over surface in hot condition with skin temperature ranging from 120–150°C.
Table 3

Base Component Composition
Ingredients Parts by weight (%)
Mill Base Examples 3A 4A 5A 6A 7A 8A 9A 10A 11A
1 Acrylic Polysiloxane ( Example 2) 16.5 16.5 16.5 16.5 16.3 13.58 12.5 10.86 8.14
2 Acrylic Polyol (Example 1) - - - - - 3.09 4 5.64 8.36
3 Wetting agent (*Acrylic copolymer with pigment affinic groups) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
4 Bentonite Clay as 10% gel form in xylene 18 18 18 18 18 18 18 18 18
5 Solvent C9 13.5 13.5 13.5 13.5 13.5 13.5 13.5 13.5 13.5
6 Titanium Dioxide 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0
7 Hydrated Magnesium Silicate 4.2 4.2 4.2 4.2 4.2 4.2 4.2 4.2 4.2
8 Zinc Phosphate 3 3 3 3 3 3 3 3 3
9 Hydrophobic Fumed Silica 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7
Stabilisation
3B 4B 5B 6B 7B 8B 9B 10B 11B
10 Acrylic Polyol (Example 1)
- 2.87 5.74 8.61 11.49 11.27 11.5 11.58 11.74
11 Acrylic Polysiloxane (Example 2)
10.66 7.94 5.22 2.51 - - - - -
12 Solvent C9 3.24 3.09 2.94 2.78 2.61 2.46 2.4 2.32 2.16
Flushing
13 Solvent C9 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00
14 Butyl Acetate 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00
Thinning Composition
15 Butyl Acetate 4.05 4.05 4.05 4.05 4.05 4.05 4.05 4.05 4.05
16 Organo Tin Catalyst as 1% solution form in xylene 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3
17 Epoxy Silane Adhesion Promoter 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3
Tinting Composition
18 Assorted Universal Tinters 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7
Total 91.65 91.65 91.65 91.65 91.65 91.65 91.65 91.65 91.65
Hardener Component Composition
Ingredient
1 3-Aminopropyltriethoxysilane 3.67 3.30 2.94 2.57 2.20 1.83 1.69 1.47 1.10
2 Solvent C9 4.68 5.05 5.41 5.78 6.15 6.52 6.66 6.88 7.25
Total 100 100 100 100 100 100 100 100 100

From the previous Table 3 the base component composition under Example 3 comprises both 3A and 3B formulations and so on, that provides for the desired stability.
The above compositions of base were prepared using premix tank followed by horizontal dyno mill and then thinning and tinting using mixer of RPM 40- 50. Ingredients 1 to 3 were added in premix tank maintaining sequence and then ingredients 4 to 9 were added sequentially under slow stirring. The premix was run for 20–25 minutes and then transferred to horizontal dyno mill, keeping viscosity of the feed 250 gm at 30°C. Two pass was given to achieve desire finish on Hegmann gauge. Then Stabilization composition with ingredients 10 to 12 were added to give final pass and then the mill was flushed using ingredients 13 and 14 and taken to the mixer. In the mixer the thinning composition, ingredients 15- 17 were added in sequence and run for 30 minutes to complete the base part. Then the base part is tinted using universal tinters to achieve the desired shade. The accelerated stability of the base component of the coating composition checked for 15 days in hot box at 55 deg. C, which showed no change in viscosity and other properties.
The hardener is prepared in a mixer separately as a solution in xylene under nitrogen blanket.
The finish of the base components was found 6+ on Hegmann Gauge.
To check mixed paint property and panel application, base and hardener were mixed in ratio 91.65:8.35 by weight.
Mixed paint viscosity was found to be in the range of 100 – 170 gm on Stormer viscometer at 30 °C, solid content by weight (%): 47 ± 1 and pot life: >5 hours in all cases.
To check wettability on hot surface mixed paint was applied on manually cleaned hot carbon steel panel having skin temperature 150°C at a dry film thickness of about 30–40 micron. After 2 hours of keeping it at 150°C, 2nd coat applied at 30–40 micron DFT and immediately kept the panel in Oven at 150°C for 4 hours. Then the panel was taken out, cooled andperformed adhesion test.
For conducting mechanical tests like abrasion resistance, hardness etc. and long term performance tests, mixed paint applied on manually cleaned carbon steel panels and for flexibility on manually cleaned tin panel. All mechanical tests performed after 7 days and panels for long term test were subjected for testing after 7 days air drying.
The coatings on the panels had the following properties as in Table 4.
Table 4
Property Example 3 Example 4 Example 5 Example 6
Pencil Hardness
as per ASTM D 3363 4H 3H 3H 3H
Flexibility
as per ASTM D 522 1/4" 1/4" 1/4" 1/4"
Impact resistance (direct)
As per ASTM D 2794 7.1 J 7.1 J 7.1 J 7.1 J
Abrasion Resistance using CS10 wheel with 1000 gm load & following 1000 cycles
as per ASTM D 4060 54.6 mg 38.8 mg 38.9 mg 40.5 mg
Gloss at 60° gloss heat as per ASTM D 523 19 – 20 18 - 19 18-19 20 – 22
Dry heat resistance at 200°C for 25 cycles ( each cycles for 8 hours at 200°C and 16 hrs at 30°C) Passes 21 cycles Passes 21 cycles Passes 21cycles Passes 22 cycles
Wetting on hot surface
(Visual) Wavy, Patchy Wavy, Patchy Smooth Smooth
Adhesion by tape test using Method A of ASTM D 3359 - X cut 5A 5A 5A 5A
Salt Spray Resistance for 500 hrs as per STM B 117 Passes with 15 mm creepage from the scribe line Passes with 8mm creepage from the scribe line Passes with 8mm creepage from the scribe line Passes with 8 mm creepage from the scribe line
Humidity Resistance as per ISO 6270 for 500 hrs Passes without any film defect Passes without any film defect Passes without any film defect Passes without any film defect
Thermal Shock Resistance for 50 cycles (Each cycles consists of 2hrs heating at 180°C followed by immediate quenching in water at 30°C) Flaked off after 21 cycles Flaked off after 24 cycles Flaked off after 24 cycles Flaked off after 37 cycles

Table-4 contd.
Property Example 7 Example 8 Example 9 Example 10 Example 11
Pencil Hardness
as per ASTM D 3363 3H 3H 3H 2H H
Flexibility
as per ASTM D 522 1/4" 1/8" 1/8" 1/8" 1/8"
Impact resistance (direct)
As per ASTM D 2794 7.1 J 7.1 J 7.1 J 7.1 J 7.1 J
Abrasion Resistance using CS10 wheel with 1000 gm load & following 1000 cycles
as per ASTM D 4060 39.2 mg 39.5 mg 37.4 mg 31.3 mg 24.7 mg
Gloss at 60° gloss heat as per ASTM D 523 23 – 25 24 - 26 30 - 32 15-16 18-19
Dry heat resistance at 200°C for 25 cycles ( each cycles for 8 hours at 200°C and 16 hrs at 30°C) Passes 22 cycles Passes 24 cycles Passes 25 cycles Passes 23 cycles Passes 11 cycles
Wetting on hot surface
(Visual) Smooth Smooth Smooth Smooth Smooth
Adhesion by tape test using Method A of ASTM D 3359 - X cut 5A 5A 5A 4A 4A
Salt Spray Resistance for 500 hrs as per STM B 117 Passes with 7mm creepage from the scribe line Passes with 5 mm creepage from the scribe line Passes with less than 2mm creepage from the scribe line Passes with 3mm creepage from the scribe line Passes with 5mm creepage from the scribe line
Humidity Resistance as per ISO 6270 for 500 hrs Passes without any film defect Passes without any film defect Passes without any film defect Passes without any film defect Passes without any film defect
Thermal Shock Resistance for 50 cycles (Each cycles consists of 2hrs heating at 180°C followed by immediate quenching in water at 30°C) Flaked off after 37 cycles Severe colour change after 5 cycles & flaked of after 39 cycles Passes 50 cycles without any flaking off except slight change in colour. Severe colour change after 5 cycles& flaked off after 40 cycles Severe colour change after 5 cycles& flaked off after 40 cycles
Result & Discussion
In Table 3, the ratio (% solid basis) of Acrylic Polysiloxane with Epoxy Functionality and Non-Reactive Acrylic polyol varies from Example 3 to Example 11 in an order of (3)100:0, (4)90:10,(5)80:20, (6)69:31, (7)59:41, (8)49:51, (9)45:55, (10)39:61 and (11) 29:71.
From Table 4, it can be clearly read that as Acrylic Polysiloxane with Epoxy Functionality decreases and Non-Reactive Acrylic Polyol increases from Example 3 to Example 9, the coating becomes more flexible and brittleness reduces. This is supported by the pencil hardness and flexibility data. Due to decrease in brittleness, the weight loss during abrasion resistance test decreases from Example 3 to Example 4 and remains almost constant from Example 4 to Example 9 (39 ± 2 mg). In case of Example 10 & 11 the values decrease due to more thermoplastic nature and softness development.
Direct Impact resistance data, humidity resistance data and adhesion data are almost similar in all cases.
Due to better wetting by Acrylic Polyol, the appearance on hot surface is becoming smooth from Examples 3 to 11.
Similar increasing trend observed in case of gloss, resistance to dry heat and thermal shock from Example 3 to 9, but values reduce in example 10 & 11 as thermos-plasticity of the coating crosses optimum limit as in Example 9.
In case of salt spray resistance, the corrosion creepage from the scribed line decreases from example 3 to 9 due to better wetting and adhesion resulted by incorporation of thermoplastic acrylic polyol having polar nature. But the value increases in case of example 10 & 11 due to decrease in thermosetting nature and cross link density.
From the above result, it can be read that Example 4 onwards and preferably Example 9 provides for coating characteristics where maximum values could be attained.
It is thus possible by way of the present advancement to provide for ambient curing heat resistant coating composition that is heat resistant upto 200°C for continuous exposure and intermittent exposure upto 250°C involving a hybrid binder base formulation containing < 20% siloxane content which is ambient to high temperature curable with aminosilanes and can be advantageously applied directly on hot metal surface at 150°C providing high corrosion resistance with good mechanical properties like abrasion resistance, flexibility, hardness etc. free of polysilazane, organosilicone phosphate, alkali metal silicate, inorganic silicic acid esters, titanate.