WO2022149157A1

WO2022149157A1 - Multifunctional polymer hybrid for direct to metal corrosion protection at low film thickness

Info

Publication number: WO2022149157A1
Application number: PCT/IN2021/051176
Authority: WO
Inventors: Vrijeshkumar SINGH; Rajeev Kumar Jain; Devchandra PANDIT; Rahul JAGTAP
Original assignee: Asian Paints Ltd.
Priority date: 2021-01-11
Filing date: 2021-12-15
Publication date: 2022-07-14

Abstract

A uniquely designed multifunctional polymer hybrid is provided suitable for readyto use single component self-priming glossy enamel for new as well as rusty mildsteel substrates for low to high corrosion zones as validated through acceleratedweathering in QUV 313 and accelerated corrosion resistance performance through ASTM B 117 Salt fog test.

Description

Title : MULTI FUNCTI ONAL POLYM ER HYBRI D FOR DI RECT TO METAL CORROSI ON PROTECTI ON AT LOW FI LM TH I CKNESS

Field of the I nvention

The present advancem ent relates to m ultifunctional polymer hybrid suitable for glossy direct to m etal anti corrosive alkyd coatings at low film thickness. More particularly present invention relates to design of m ultifunctional polymer hybrid of alkyd resin for single pack ready to use corrosion and weather resistant self prim ing enamel for maintenance of old m ild steel structures which is an advancem ent over presently required extensive su rface preparation and use of m ulti product and m ulti coat system that is quite cumbersom e & not feasible for dom estic consum ers and synthesis thereof.

Backg round of the I nvention

Alkyds and chem ically modified alkyd resins are the condensation products of poly- basic acids and polyhydric alcohols. They are used in liquid organic coatings for the architectural, industrial, automotive, and industrial m aintenance m arkets. Alkyds are also known as oil-modified polyesters because of the presence of vegetable or marine oils or other fatty acids. These oils are co- reacted into the polyester backbone. The type of oil or fatty acid present in the alkyd contributes to its oxidative cure characteristics. I n a chem ical sense, alkyds are polyesters that are form ulated with drying or nondrying oils. I n contrast, polyesters are oil free.

Most alkyds are film -form ing polymers with a relatively low glass transition temperature (Tg ) , i.e. , below 0°C having inherently excellent pigment wetting characteristics and readily accept additives to form coatings with a wide range of appearance, perform ance, and application characteristics. Alkyds and modified alkyds have a good combination of hardness and flexibility, very acceptable corrosion resistance, good gloss retention, good adhesion to ferrous and nonferrous m etals, and other properties that m ake them acceptable for use on wood, m etal, plastic, composite, and other substrates. They are used in areas such as architectural coatings, automotive under-body and under- hood coatings, coil coatings, drum and metal container coatings, electrical insulating enamels, exterior trim paints, maintenance paints, and similar end uses.

However, the lack of hardness, hydrolytic stability, and alkali resistance diminished alkyd usage. Alkyds also have poor outdoor weatherability and color retention.

Alkyds are often modified with other polymeric materials for particular property attainment. Three major classifications of alkyds are those designed for conventional solids, higher solids, and water-borne coatings. Because there are a large variety of commercially available intermediates and chemical modifiers, i.e. , monomers, for the preparation of alkyds, they continue to be a very versatile type of polymers for coatings and printing inks.

The higher solids of alkyd permits good paint buildup with a minimum number of coats. Due to this versatility of alkyds, much of the early work involving siloxane and organic resins was in the area of siloxane-modified alkyds. The importance of a siloxane-alkyd system is derived from the synergistic properties of the two resins enabling the resultant copolymer to have higher temperature resistance and better exterior durability. In the grafted hybrid resins, the control of microphase separation led to better overall properties. Alkyd-siloxane hybrids are used as lacquer resins and protective coatings in the electric industry due to the low- dielectric constants and, also find use as coatings for lawn furniture. However, in the presence of water and heat, the silicone-alkyd polymer may break down into its starting components. Once this occurs the alkyd will continue to oxidize and form water-soluble polymers.

The corrosion of mild steel is a major economic issue impacting domestic and industrial users. Thus, efforts to develop more efficient and environmentally compliant methods to prevent corrosion have been the area of research around the globe. Some references are invited as per the following:

US5539032 discloses about coatings comprising of high dosages of anticorrosive pigments like aluminum triphosphate, zinc benzoate and an alkaline earth metal phosphate using Silicone Alkyd co-polymer. The coating is recommended for pretreated and unprimed metal to be cured at ambient or elevated temperat ure. The preferred embodiment of invention mentions corrosion resistance for periods ranging up to 500 hours in SO2- Salt Fog test and up to 1000 hours in the salt Fog test for coatings applied up to about 10 mils thickness and preferably up to 1 -3 mils.

US5089551 describes providing high-gloss and good adhesion/flexibility. The coating comprises of a Silicone alkyd resin and corrosion inhibiting pigments consisting of zinc-barium phosphate, zinc molybdate and at least one zinc salt of a benzoic acid and an organic solvent and does not mention any superior performance characteristics of the coating.

EP1499690 A1 and US7208537 B2 discloses about self-priming rapid curing chromate free corrosion resistant coating composition based on a polyvinyl terpolymer and an alkyd resin with hydroxyl number of 80-200 along with mineral acid catalyst and one or more organic solvents and a drying agent. The composition can be applied as a clear coat or as a pigmented composition with addition of pigments on ferrous and non-ferrous metallic substrate and is particularly suitable for continuous coil coating lines for curing at high temp of 180-280°C.

US5021489 relates to corrosion inhibiting film forming compositions which displace moisture from the metal substrate but does not mention about performance characteristics. Such coating compositions comprise of an acrylic resin, a silicone resin and a copolymer derived from silicone and alkyd resin. The oil soluble petroleum sulfonates along with alkyl am monium phosphate has been used to inhibit corrosion of the metal substrate. The organic solvent used comprises of aromatic hydrocarbon, glycol ether and cellosolve acetate. Flowever, the claims cited do not speak about performance characteristics of the coating.

US20100174035 discloses urethane and siloxane modified water-reducible alkyd resins, comprising moieties derived from polyhydric alcohols, modified fatty acids made by grafting olefinically unsaturated carboxylic acids onto fatty acids, ungrafted fatty acids, silanol or alkoxysilyl functional siloxane oligomers or polymers and polyfunctional isocyanates. This prior art relates to water reducible alkyd wherein high acid value in the alkyd / acrylic moiety is neutralized and then dispersed in water.

WO201 9102491 co-pending application teaches formulation and process of preparing a functionalized urethane alkyd resin that relates to a siliconized urethane alkyd resin obtained from an alkyd based on semi drying/ drying Oils or their fatty acids having high iodine number of 120-170 (gm l2/100gm) and having acid value 10 mg/KOH per gm or less attained by grafting of epoxy alkyl alkoxy silane or silanol functional silicone resin onto alkyd backbone and subsequent urethanization of the organosilane grafted alkyd.

US4719254 provided epoxy ester-modified alkyd resin formulations that can be pigmented comprising: (i) from about 70 to 80 wt % soya modified alkyd resin; mixing (ii) from about 4.75 to 10 wt % epoxy ester resin; (iii) from about 4.75 to 10 wt % silicone modified alkyd resin; and (iv) from about 0.5 to 10 wt % compatible solvent. These alkyd resin formulations can be pigmented to provide a wide variety of pigmented, epoxy ester modified, air dry alkyd enamels.

EP3263617 B1 disclosed alkoxysilane-functionalized and allophanate- functionalized urethanes comprising the reaction product of

I. A) alkoxysilane group-containing monourethanes A) of the formula 1 Rn(0R1)3-nSi-R2-NH-(C=0)-0R3 formula 1 where Rn, R1 , R2 and R3 are each independently hydrocarbyl radicals having 1-8 carbon atoms, which may be linear, branched or cyclic, or else may be integrated together to form a cyclic system, and n is 0-2, and

B) at least one diisocyanate B), in a molar ratio of A) to B) of from 1.0: 1.5 to 1.0:0.6, preferably 1.15:1 to 0.85: 1 , particularly preferably 1:1, optionally in the presence of at least one catalyst K) ,

II. and the subsequent reaction

C) with at least one diol and/or polyol C), optionally in the presence of at least one catalyst K), in the ratio of the NCO groups of reaction product I. to the OH groups of the diol and/or polyol II. C) of from 1.0:1.5 to 1.0:0.6, preferably 1.15:1 to 0.85:1, particularly preferably 1:1. This is thus alkoxysilane and urethane crosslinkers used as two component polyurethane system and not a single component urethane alkyd modified with epoxy and silicone resins.

US20160145448A1 (High solids coating composition comprising an alkyd resin and isoamyl acetate) relates to a non-aqueous liquid coating composition comprising an alkyd resin and a volatile organic solvent, wherein at least 15% by weight of the organic solvent is isoamyl acetate wherein the coating composition is provided as a storage stable one-component composition ready for application. The coating composition of this prior art may also be provided as a kit of separately stored parts that comprises a binder module comprising hydroxyl-functional alkyd resin and a hydroxyl-reactive crosslinker module preferably polyisocyanate, wherein the modules are m ixed prior to application of the coating composition.

KR2016050644A on Water soluble epoxy alkyd hybrid resin with good corrosion resistance discloses hybrid resin comprising a main chain prepared from a polycarboxylic acid, a polyol, an unsaturated fatty acid, and an epoxy resin and a side chain prepared from a polyol and an unsaturated fatty acid, wherein the unsaturated fatty acid is polymerized with an acrylic monomer.

CN102924699 A on alcohol acid resin, preparation method of alcohol acid resin, and anti-corrosion paint using same provides an alcohol acid resin prepared by trimethylolpropane, phthalic anhydride, adipic acid anhydride and isononanoic acid. The anti-corrosion paint using alcohol acid resin consists of alcohol acid resin, ethenyl resin, ethenyl triethoxysilane and dryer W-2000B. The anti-corrosion paint coated film showed no change in being subjected to salt mist for 100 h , and to water for 360h but the coated film de-colors lightly since being subjected to manual aging for 1 OOh.

CN102952261 A teaches alkyd resin, preparation method of alkyd resin and three-dimensional network anticorrosive coating using alkyd resin comprising a reaction product of mixture of soybean oil, benzoic acid and pentaerythritol, yellow lead, and phthalic acid anhydride in dimethylbenzene, subsequently thinned with gasoline. The three-dimensional network anticorrosive coating using the alkyd resin consists of the alkyd resin, vinyl ester resin, vinyl triethoxysilane, flatting agent and dryer. The three-dimensional network anticorrosive coating provided by the advancement has the advantages that the situations of blistering, rusting and falling do not occur in a water resistance test, neutral salt mist resistance test for 120h, and the situations of blistering, rusting, cracking and falling do not occur in an artificial weather aging test which lasts 100 h .

EP1 292400 B1 relates to methods of coating metal substrates, especially bare metal substrates which have not been chemically and/or mechanically altered with a pretreatment process applying a two-component urethane coating composition directly to the bare, untreated metal substrate so as to make a coated metal substrate, wherein one or more components of the two-component urethane coating composition comprise a m ixture of compound (I) and compound (I I), a silane oligomer (B), and mixtures thereof, wherein compound ( I) is the reaction product of (a) at least one difunctional carboxylic acid, (b) at least one trifunctional polyol, (c) at least one chain stopper, and (d) phosphoric acid, and compound (I I) comprising one or more carboxy phosphate esters and the silane oligomer (B) comprises the reaction product of an isocyanate functional compound (A) and a coupling agent (X) comprising

(i) at least one alkoxysilane functional group, and

(ii) at least one group reactive with isocyanate selected from the group consisting of thiol groups, secondary amine groups, primary amine groups and mixtures thereof, wherein the silane oligomer (B) comprises an average of at least two free isocyanate groups.

EP1 9471 54 relates to a rust preventive pigment-containing epoxy resin (corrosion resistant) paint composition, a coating film prepared from the paint composition, a substrate coated with the coating film and a method for preventing corrosion using the paint composition. It discloses a rust preventive pigment-containing polyfunctional epoxy resin paint composition comprising: (A) a polyfunctional epoxy resin, (B) a modified aliphatic polyamine, (C) a rust preventive pigment, ( D) a silane coupling agent and (E) a moisture absorbent, wherein the polyfunctional epoxy resin (A) contains from 6 to 9 epoxy groups, as determ ined with a theoretical value calculated by dividing its number average molecular weight Mn (measured with GPC relative to polystyrene standards, referred to hereinafter) by epoxy equivalent and avoids the use of any fluorosilane.

US7205353B2 discloses self-priming coating composition based on a vinyl terpolymer, a monomeric or oligomeric alkoxy amino resin cross linker and a m ulti component combination of two or more resins selected from (a) oligomeric saturated polyester resin, (b) oligomeric unsaturated polyester resin dissolved in an unsaturated monomer with a free radical initiator (c) oligomeric bifunctional phenolic resole resin and (d) oligomeric epoxy resin (e) low molecular weight polyurethane resin and (f) short to medium oil alkyd resin, wherein said vinyl terpolymer is predominantly polyvinyl formal with polyvinyl alcohol and polyvinyl acetate as two other co-polymers. The composition can be applied as a clear coat or as a pigmented composition with addition of pigment on ferrous and non-ferrous metallic substrate and is particularly suitable for continuous coil coating lines for both dark and light colour metal coatings.

Triwulandari, E. et al (Hydrolysis and Condensation of Alkoxysilane for the Preparation of Hybrid Coating Based on Polyurethane/ Polysiloxane-Modified Epoxy: Polymer Science, Series B March 2019, Volume 61 , Issue 2, pp 180-188) relates to preparation of a hybrid coating based on hydrolyzed and condensable alkoxysilane and epoxy/ polyurethane resin. All hybrid coating products were found to have better mechanical properties than epoxy resin before modification.

Allauddin, S. et al. on Synthesis and Properties of Alkoxysilane Castor Oil and Their Polyurethane/Urea-Silica Hybrid Coating Films: ACS Sustainable Chem. Eng. 2013, 1 , 8, 910-918 developed a novel methodology to introduce hydrolyzable - S1-OCH3 groups in the castor oil backbone that has been used subsequently for the development of polyurethane/urea-silica hybrid coatings. The ASCO was further reacted with different ratios of isophorone diisocyanate ( I PD I ) to get an isocyanate-term inated hybrid polyurethane prepolymer that was cured under atmospheric moisture to get the desired coating films. The Tg and hydrophobic character of the hybrid coating films found to increase with an increasing NCO/OH ratio. The alkoxy silane-modified castor oil-based coatings have shown better mechanical and viscoelastic properties in comparison to the control (unmodified castor oil) coatings.

From the above it is apparent that the anti-corrosive paints available in the market are based on epoxy, polyurethane, organic or inorganic zinc-rich coatings etc. largely for industrial use with the resins being either mixed or condensed. These coating compositions are mostly 2K systems requiring measured quantities of the components to be m ixed prior to use and employ hazardous aggressive solvents. Limited pot life and difficult to clean the coating equipment after the job is another hassle in 2K coating systems. Such coating systems generally require multiple coating layers to be deposited to achieve desired overall high dry film thickness necessary for barrier protection. It is practically not feasible to cater to a wider cross-section of domestic users to apply such kind of a coating system.

In addition for alkyd paints the majority of prior arts are based on expensive alkyd silicone co-polymers in combination with other resins and employ high dosage of multiple corrosion inhibitive pigments and not m uch is mentioned about improvements in weathering performance as well as application on rusty substrate. Some of the references talk about high gloss but same does not find mention under the experimental test results. Moreover, these products would require two days of application which is cumbersome in today’s context for faster delivery, hence there is need for improved single component urethane alkyd addressing the above limitations and can be applied in single day as a single pack to provide for similar or better performance of a 2K coating system .

Objectives of the I nvention

Thus the primary objective of the present invention is to provide for alkyd based multifunctional polymer hybrid wherein alkyd backbone would have m ultiple functionality built into it to enhance corrosion and weathering performance. Another objective of the present invention is to provide for said alkyd based m ultifunctional polym er hybrid having grafted epoxy, silicone and urethane functionalities in the alkyd backbone with improved corrosion resistant and weathering perform ance, and a process or synthesis of the sam e. Yet another objective of the present invention is to provide for said alkyd based m ultifunctional polymer hybrid com prising base alkyd having custom ized fatty acids of iodine value preferably 145- 160 (gm I2 / 100 gm) , polyols and dibasic acid, that would enable epoxy modification by involving free acid groups in alkyd backbone, to be further reacted with polysiloxane resin followed by further incorporation of urethane linkages into the alkyd backbone by employing aliphatic / cycloaliphatic polyisocyanate.

Another obj ective of the present invention is to provide for select said base alkyd for alkyd based m u ltifunctional polym er hybrid such that would be having high iodine value preferably 145- 160 together with select acid value in the range of 25- 35 mg KOH/gm representing free carboxyl groups for further reaction with epoxy resin at elevated tem perature wherein the alkyds would have excess hydroxyls in the alkyd backbone as well as hydroxyls generated from carboxyl-epoxy reaction to be partially reacted with suitable polyisocyanate to obtain m ultifunctional alkyd hybrid. Yet another objective of the present invention is to provide for epoxy, silicone and urethane functionalities grafted m ultifunctional alkyd that would achieve excellent compatibility with m ineral turpentine Oil (MTO ) (m inim um 1 : 10 : : alkyd : MTO) which is a m ix of aliphatic and aromatic hydrocarbons and is the preferred solvent for 1 K air drying alkyd-based coatings. Another objective of the present invention is to synthesize said alkyd based m ultifunctional polym er hybrid having alkyd, epoxy, silicone and urethane moiety from a single pot reaction.

Another preferred objective of the present invention is to provide coating composition suitable for 1 K air drying topcoat coating involving said alkyd based m ultifunctional polymer hybrid having alkyd, epoxy, silicone and urethane grated on the alkyd backbone.

Another objective of the present invention is to provide for said 1 K air drying topcoat coating composition comprising said alkyd based m ultifunctional polym er hybrid requiring 2-coats for finishing the coating with recoat time of 6 hours.

Another objective of the present invention is to provide said 1 K air drying topcoat coating com position wherein said coating composition would provide sufficiently thin coating sim ilar to 2K system .

Another objective of the present invention is to provide said 1 K air drying topcoat coating composition coupled with anticorrosive pigm ents and additives as known in the prior art that would exhibit high corrosion resistance and weathering performance sim ilar to 2K coating system .

Sum m ary of the invention

The primary em bodiment present invention is directed to provide m ultifunctional polymer hybrid com prising urethane modified silicone-epoxy-alkyd hybrid resin having silicone and epoxy resins grafted onto base alkyd backbone, said grafted epoxy content being 4-6 % , said grafted silicone content being 5-8 % and urethane content being 4-6 % on alkyd solids, enabling weight average mol. wt. of 50000-70000, fast surface drying in 70-80 m in, tack free drying in 4-5 hou rs, hard drying within 16 hours and gloss at 20° 80-86, scratch hardness pass of 1300- 1400gm .

Another em bodim ent of the present invention is directed to provide said Multifunctional polymer hybrid wherein said urethane modified silicon-epoxy-alkyd hybrid resin is a reaction product of 2- 3 wt. % polyisocyanate and 95-96 wt.% silicon-epoxy-alkyd hybrid resin having acid value in the range of 2-3 mg KOH/g; said silicon-epoxy-alkyd hybrid resin being a reaction product of 3-5 wt. % silicone resin and 95-97 wt.% epoxy alkyd resin having acid value of about 5 mg KOH/g and hydroxyl value 80-85 mg KOH/g; said epoxy-alkyd hybrid resin being a reaction product of 5-7 wt.% epoxy resin and 90-92 wt.% base alkyd resin having acid value of 25-45 mg KOH/g which is a condensation product of select fatty acid comprising : saturates C16/C18 - 5- 12% , C18: 1 - 23-30% , C18: 2 - 32-40% and C18: 3 - 20-25% and having high iodine value of 145- 160 (gm 12 / 100 gm) , and polyhydric alcohols, polybasic carboxylic acids and anhydrides thereof including aromatic carboxylic acids and anhydrides.

I n another em bodiment of the present invention is directed to provide said Multifunctional polym er hybrid wherein said epoxy alkyd resin is thinned epoxy alkyd resin thinned with m ineral turpentine oil and xylene at thinning ratio of ratio- 85: 15.

Another em bodim ent of the present invention is directed to provide said Multifunctional polymer hybrid wherein said base alkyd resin includes fatty acid preferably distilled fatty acid in the range of 50 -52 wt.% , polyhydric alcohols preferably pentaerthritrol in the range of 19-21 wt.% , monobasic and dibasic carboxylic acid and anhydrides including aromatic analogues preferably phthalic anhydride, benzoic acid in the range of 15-23 wt.% enabling said high iodine value in the range of 145- 160 (gm 12 / 100 gm) and select acid value of 25-45 mg KOH/g and more preferably 25-35 mg KOH/gm due to free acid groups in alkyd backbone, adapted for said select epoxy-alkyd hybrid resin and said m ultifunctional polymer hybrid enabling m etal corrosion protection at low film thickness and a single pack ready to use corrosion and weather resistant self prim ing enamel.

Yet another embodiment of the present invention is directed to provide said Multifunctional polymer hybrid wherein said fatty acid comprises saturated fatty acids includes myristic, palm itic and stearic acids preferably palm itic and stearic acid alone or in m ixture; monounsaturated fatty acids includes oleic, elaidic and vacentic acids preferably oleic alone or in m ixture; bis unsaturated fatty acids includes linoleic, Linolelaidic preferably linoleic alone or in m ixture; Tris unsaturated fatty acids preferably linolenic alone or in m ixture.

Further em bodiment of the present invention is directed to provide said Multifunctional polymer hybrid wherein said epoxy resin includes epoxy novolac resin, preferably epoxy novolac resin with m ultifunctionalty, said silicone resin includes hydroxyl functional silicone resin preferably low molecular weight hydroxyl functional silicone intermediate, and said urethane modification to incorporate urethane linkages into the alkyd backbone involves aliphatic / cycloaliphatic polyisocyanate including hexam ethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate and diphenylmethane diisocyanate preferably isophorone diisocyanate and hexam ethylene diisocyanate

Another preferred aspect of the present invention is directed to provide a single pot process for the synthesis of said Multifunctional polymer hybrid comprising the steps of: a. providing base alkyd polyol resin with an acid number of 25-45 mg KOH /gm ; b. epoxidizing said base alkyd polyol resin with epoxy resin yielding epoxy alkyd hybrid resin with acid value of < 5 and hydroxyl value 80-90 mg KOH/gm ; c. siliconizing epoxy alkyd hybrid resin by reacting said epoxy alkyd resin with polysiloxane resin to obtain silicon-epoxy-alkyd hybrid resin; and d. urethane modifying silicon-epoxy-alkyd hybrid resin to incorporate urethane linkages to obtain urethane modified silicone-epoxy-alkyd hybrid resin having select acid value of < 5 mg KOH/g by reaction of said silicon-epoxy-alkyd hybrid resin with isocyanates. Further aspect of the present invention is directed to provide said process for synthesis of said Multifunctional polymer hybrid wherein said step (a) involves reacting in inert atmosphere one or more polyhydric alcohols with one or more polybasic acids /acid anhydrides or arom atic analogues, hydroxycarboxylic acids and monofunctional carboxylic acids along with oils/fatty acids in presence of a catalyst and reflux solvent at a reaction tem perature of 230°C till acid number of 25-45 mg more preferably 25-35 mg KOH/gm is achieved, to produce the base alkyd resin com ponent; wherein said step (b) involves reacting in inert atmosphere base alkyd resin as obtained in the previous step (a) with epoxy resin at 235 °C till the acid value below 5 mg KOH/g and hydroxyl value 80-90 mg KOH/gm is reached together with Gardner viscosity D- at 55.2% solid in Mineral turpentine oil and Xylene (Thinning ratio-85: 15) ; wherein said step (c) involves reacting in inert atmosphere by heating said epoxy alkyd hybrid resin obtained from step (b) above with polysiloxane resin in presence of a catalyst at a tem perature range of 160- 165° C for about 3 hours till achieving a constant Gardner viscosity ( D- to E- F) towards clear material clarity on glass plate indicating complete compatibility of the obtained silicon-epoxy-alkyd hybrid resin; wherein said step (d) involves reacting under inert atmosphere said silicon-epoxy- alkyd hybrid resin in Mineral Turpentine oil through its free hydroxyls with anyone of aliphatic cycloaliphatic and aromatic polyisocyanates or their derivatives after raising tem perature of the batch to 75°C till a tem perature of 105- 1 10 °C followed by adj usting viscosity with xylene to reach the values of Z-Z1 on Gardener scale, and attaining therefrom urethane modifying silicon-epoxy-alkyd hybrid resin wherein all the reactions take place in-situ in a single pot.

Detailed description of the invention As discussed hereinbefore, while alkyd based 1 K Air drying top coats are known for bottom of the pyram id economical paints providing limited corrosion resistance, non-yellowing and weathering performance while having long recoat time of > 12 hr, and while coatings based on urethanes have been used when the application requires corrosion resistance and weather resistance with an ambient cure response, they are generally high in volatile organic components (VOC’s). Further coatings based on silicone alkyds have been used for applications requiring an ambient cure schedule and high temperature resistance. The silicone alkyds provide good U. V. light resistance and since it contains between 20-30 % (by wt.) silicone it is also useful for high temperature resistance. However, in the presence of water and heat, the silicone-alkyd polymer may break down into its starting components. Once this occurs the alkyd will continue to oxidize and form water- soluble polymers as referred in CA2310283C.

Considering single component oxidative crosslinking, high renewable content and possibility to employ less hazardous Mineral Turpentine oil as solvent, it was considered to explore and build desired aesthetics and high weathering and corrosion resistance performance in an alkyd coating by grafting multifunctional monomers which are capable to deliver very high corrosion resistance performance at low film thickness. Presently, there is only one product based on a co-pending application (Application Number 201721042425) as mentioned hereinbefore upon the above considerations in market i.e. Asian Paints Rust Shield Enamel, available relying on single component urethane alkyd chemistry providing the attributes of self priming, high gloss, fast drying, non-yellowing and excellent weathering (Gloss/ Color retention) as tested on QUV 313 (ASTM G53-96) and corrosion resistance as per Salt Fog resistance of m in 800 hours (ASTM B 117) when applied at 75-90 microns in 3 coats by brush at an interval of m inimum 8 hours. Product requires two days of application which is cumbersome in today’s context of faster delivery.

The present invention thus overcomes the above stated limitations through uniquely designed/ form ulated m ultifunctional polymer hybrid alkyd recipe involving customized fatty acid composition (Saturates C16/C18 - 5-12% , C18: 1 - 23-30% , C18: 2 - 32-40% and C18:3 - 20-25% ) having high iodine value of 145- 160 (gm I2 / 100 gm). Said customized fatty acid is available commercially and purchased as packaged product from supplier (M/s VVF Lim ited, Taloja MI DC, District Raigad, Maharashtra, I ndia) Fatty acid mix with such fatty acid composition is obtained from hydrolysis of sem i drying / drying oils followed by fractional distillation at elevated temperature under reduced pressure. Such high iodine value based fatty chain in the alkyd backbone enhances auto-oxidative crosslinking which on further reaction with novolac epoxy, silicone resin and polyisocyanate strengthens the alkyd back bone resulting in high corrosion resistance performance.

Base alkyd recipe is designed and synthesized using custom ized fatty acid, polyols and dibasic acid. Epoxy modification is carried out on the base alkyd with the aid of free acid groups present in alkyd backbone. The epoxidized alkyd resin thus obtained is further reacted with silicone followed by incorporation of urethane linkages into the alkyd backbone employing aliphatic/ cycloaliphatic polyisocyanate to yield the designed multifunctional polymer hybrid having epoxy ester / silicone and urethane linkages in the alkyd backbone.

In the present invention said multifunctional polymer hybrid has very high molecular weight of > 50000 weight average molecular weight with epoxy ester content > 6% , polysiloxane content > 5% and urethane content > 7% on alkyd solid. Such m ultifunctional polymer hybrid alkyd resin was combined with paint design incorporating corrosion inhibiting pigment and additives known in the art to achieve high corrosion resistance and weathering performance while ensuring high gloss at low film thickness. Mineral turpentine oil ( MTO) used as the thinner during the synthesis of desired m ultifunctional polymer hybrid, also known as white spirit, a m ixture of aliphatic, open-chain or alicyclic C7 to C12 hydrocarbons, is insoluble in water and is the most widely used solvent in the paint industry preferably used in paints, lacquers and varnishes. Odorless m ineral spirits (OMS) obtained after removal of the more toxic arom atic compounds, or high flash point grade are also available in the m arket.

The process followed for the present invention a. The alkyd interm ediate was designed and synthesized with sufficiently excess carboxylic functionality in such a fashion that the acid value ranges between 25 and 35 mg KOH/gm enabling further reaction of said free carboxylic groups with epoxy resin till acid value of < 5 is achieved followed by dilution in m ineral turpentine oil (MTO) . I n the present invention preferably epoxy novolac resin was employed for grafting on alkyd backbone to achieve superior corrosion resistance performance. Epoxy resin content and reaction conditions were carefully selected at this stage to ensure compatibility with MTO and to prevent premature gelation during subsequent grafting with silicone resin and polyisocyanate. Reaction with epoxy resin created additional OH functional sites facilitating further reaction and a branched structure of higher molecular weight polymer hybrid. b. Epoxidized alkyd thus obtained having epoxy based ester group after reaction with carboxylic group of the alkyd that thereby generates a secondary -OH group, was further reacted with silicone resin intermediate to impart siloxane functionality known to provide enhanced corrosion and weathering resistance. c. Thus synthesized silicone modified epoxidized alkyd from the previous step was further reacted with selective quantity of polyisocyanate/s in controlled conditions to get a high molecular weight branched alkyd hybrid having m ultiple in built functionalities sourced from unsaturated fatty acid chain, epoxy, silicone and urethane thereby creating synergistic effect in respect of performance attributes of the coating obtained thereof.

EXAM PLES Exam ple 1

Synthesis and properties of Epoxidized Alkyd ( 1 A)

The Epoxidized Alkyd ( 1 A) was synthesized according to the method as described below

Table-1 : Reagents and chemicals used for Epoxidized Alkyd ( 1 A) synthesis

Reaction vessel, equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer and Dean Stark apparatus for water separation generated from the reaction, is charged with Distilled fatty acid, Mono Pentaerythritol 98% , Phthalic anhydride, Benzoic acid, Mixed xylene and DBTO with the preferred quantities as mentioned in Table- 1.

Raising the reaction temperature slowly to 230°C till acid value reaches 45-65mg KOH/g;

Cooling the reaction mass to 180- 190°C;

Adding epoxy resin slowly into the reaction m ixture and raise batch temperature to 230-235°C;

Continuing the reaction to attain acid value below 5 mg KOH/g and Gardner viscosity C-D at 55% solid in Mineral turpentine oil and Xylene with Thinning ratio- 85: 15) .

The Hydroxyl value of the resulting resin is 88 mg KOH/g and average molecular weight (Mw) is 7136. During processing of the batch after addition of epoxy resin frothing was observed.

Synthesis and properties of Epoxidized Urethane Alkyd ( B1 1 and B21 ) Table-2 : Reagents and chemicals used for Epoxidized urethane Alkyd (B1 1 and B21 ) synthesis

Reaction vessel equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer is charged with resin obtained in the previous step with the quantities as mentioned in Table-2.

Raising the batch temperature to 75° C and adding Isophorone di isocyan ate (I PDI) slowly ( 10- 15 mins) in the reaction medium followed by Mineral Turpentine oil;

Raising the reaction temperature to 105- 1 10°C and continuing till a constant viscosity is achieved; Adjusting the viscosity of the reaction mass with m ixed xylene optionally.

The obtained Epoxidized Urethane Alkyd resin was formulated as clear lacquer following standard protocol as follows to check the drying properties of the said resin.

Clear lacquer Formulation of synthesized Alkyd : Form ulation of clear lacquer comprising said Epoxidized Urethane Alkyd resin involves the following reagents: Table 3 : Reagents and chem icals used for Epoxidized urethane alkyd clear lacquer formulation and method to check the drying of alkyd in clear formulation:

Process: Adding Mineral Turpentine Oil (30gm) into a tin container having 100 gm resin and mixing well to get uniform mixture; Adding Cobalt octoate (6% ), Zirconium octoate ( 18% ), Calcium octoate (3%) and MEK oxime consecutively and mixing well; Keeping the sample for overnight maturation after closure of the container; Checking the viscosity of sample after maturation and adjusting the same to 65 seconds in Ford cup B4 @ 30°C i.e. application viscosity by Mineral Turpentine oil. The formulated resin as obtained by applying the above process are applied by using brush on tin panel @ 20± 5-micron dry film thickness and subsequently the drying properties such as surface dry, tack free and hard dry time respectively are noted.

Table-4 : Physical properties of Epoxidized Urethane Alkyd resin

For both the clear lacquer form ulation involving B1 1 or B21 drying is found to be slower than the conventional enamel paint product and hence not evaluated in paint. Exam ple 2

Synthesis and properties of Epoxidized Alkyd ( 2A)

The Epoxidized Alkyd (2A) was synthesized according to the m ethod as described below

Table-5 : Reagents and chem icals used for Epoxidized Alkyd ( 2A) synthesis

Following the same experimental protocol for Epoxidized Alkyd ( 1 A) as of Exam ple- 1 reaction vessel equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer and Dean Stark assem bly for water separation generated from the reaction, is charged with distilled fatty acid, mono Pentaerythritol 98% , Phthalic anhydride, Benzoic acid, Mixed xylene and DBTO with the quantities as m entioned in Table-5 above;

Raising the reaction temperature slowly to 230°C till acid value reaches < 20 mg KOH/g

Cooling the reaction mass to 180- 190°C;

Adding epoxy resin slowly in to the reaction m ixture and raising batch temperature to 230-235°C;

Continuing the reaction to attain acid value below 5 mg KOH/g and Gardner viscosity C- D at 55% solid in Mineral turpentine oil and Xylene Thinning ratio- 85: 15) .

The Hydroxyl value of the resulting resin is 84 mg KOH/g and average molecular weight (Mw) is 9230. Batch processing time is found to increase by > 50% as the reaction is very slow, reduction in acid value is slow due to less availability of acid groups to open up the epoxy ring and getting consumed during processing of the batch. Also the colour of the product becomes dark.

Synthesis and properties of Epoxidized Urethane Alkyd ( B1 2 and B22) Table-6 : Reagents and chem icals used for Epoxidized urethane Alkyd (B12 and B22) synthesis

Reaction vessel equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer is charged with resin obtained in the previous step with the quantities as mentioned in Table-6.

Raising the reaction temperature to 105-1 10°C and reaction continued till a constant viscosity is achieved; Adjusting the viscosity of the reaction mass optionally with mixed xylene.

The Physical properties of Epoxidized Urethane Alkyd resin obtained from t he previous step are as follows

Table 7 : Properties of Epoxidized Urethane Alkyd resin (B12 & B22)

The obtained Epoxidized Urethane Alkyd resin when form ulated as clear lacquer following standard protocol (as per Example 1 ) displayed the following properties:

Physical properties of B12 as clear lacquer: (Surface drying-2.0 hrs, tack free drying- 5.8 hours, hard drying-16 hours and gloss at 20° is 82-83, hardness of the film is very less, scratch hardness fails at 900 gm),

Physical properties of B22 as clear lacquer: (Surface drying- 1.7 hrs, tack free drying- 5.0 hours, hard drying-16 hours and gloss at 20° is 77-80, hardness of the film is very less, scratch hardness fails at 1000 gm) .

Similar to Example-1 for Example 2 also drying of clear lacquer is slower than the conventional enamel paint product in both the experiments hence not evaluated further in paint.

Exam ple 3

Synthesis and properties of Epoxidized Alkyd (3A)

The Epoxidized Alkyd (3A) was synthesized according to the method as described below

Table-8: Reagents and chemicals used for Epoxidized Alkyd (3A) synthesis

Following the same experimental protocol for Epoxidized Alkyd (1 A) as of Example- 1 reaction vessel equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer and Dean Stark apparatus for water separation - generated from the reaction, is charged with Distilled fatty acid, Mono Pentaerythritol 98% , Phthalic anhydride, Benzoic acid, Mixed xylene and DBTO with the quantities as m entioned in Table-8.

Raising the reaction tem perature to 230°C till acid value reaches 25-35 mg KOH/g ; Cooling the reaction mass to 180- 190°C; Adding epoxy resin slowly into the reaction m ixture and raising batch temperature to 230-235°C

Continuing the reaction to attain acid value below 5 mg KOH/g and Gardner viscosity C- D at 55% solid in Mineral turpentine oil and Xylene (Thinning ratio- 85: 15) . The Hydroxyl value of the resulting resin is 85 mg KOH/g and average molecular weight ( Mw) is 1 1456.

Synthesis and properties of Epoxidized Urethane Alkyd ( B1 3 and B23) Table-9 : Reagents and chem icals used for Epoxidized urethane Alkyd ( B1 3 and B23) synthesis

Reaction vessel equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer is charged with resin obtained in the previous step with the quantities as m entioned in Table-9. Raising the batch temperature to 75° C and adding Isophorone diisocyanate ( I PD I ) slowly ( 10- 15 m ins) in the reaction m edium followed by Mineral Turpentine oil; Raising the reaction temperature to 105-1 10°C and continuing the reaction till a constant viscosity is achieved.

Optionally, adjusting the viscosity of the reaction mass with m ixed xylene.

The Physical properties of Epoxidized Urethane Alkyd resin obtained from the previous step are as follows

Table-10 : Properties of Epoxidized Urethane Alkyd resin

Unlike Example- 1 & 2 for Example 3 since drying of clear lacquer is somewhat faster than the conventional enamel paint product, the same was thus evaluated further in paint.

C. Preparation and key properties of w hite enamel based on Epoxidized Urethane Alkyd

Paint processing Method: Sand Milling Paint form ulation of the present invention comprises the following steps:

1 . Pre m ixing

2. Grinding

3. Stabilization

4. Thinning

Table-1 1 : Reagents and chem icals used for form ulation

Pre m ixing :

1. Charging resin, EFKA FA 4608, Soyalecithane, Bentone SD- 1 , Mineral Turpentine oil, T1O2 and Zinc phosphate m icronized in to the vessel. 2. Mixing the m ass at 1000 to 1200 RPM by using High Speed Disperser for 3-

4 Min.

3. Adj usting the consistency to required level and optionally adding solvent or resin, in case required consistency is not achieved.

Grinding :

1. Charging the required amount of sand into the vessel.

2. Grinding the m aterial uniform ly for 7-8 m in (One pass) at 1800rpm to get desired dispersion.

3. Checking the fineness of grinding by using Flegm ann gauge providing value of at least 6.5 4. Applying second pass ( additional grinding of 7-8 m in) optionally if finish is less than 6.5 to get the desired finish. Stabilization :

1 . Take some part of stabilization material, add sam e amount of grinded paint material to it and check finish again. To confirm there is no finish reversion after addition of stabilization part.

2. Reduce the speed of HSD to 800- 1000 RPM.

3. Add slowly uniform ly m ixed stabilization part into the vessel.

4. Mix the mass for 3-5 m in.

Thinn ing :

1. Strain the m ill base using 240 m icron nylon mesh in to the separate container.

2. Add resin, solvent, additives and driers in to the container and m ix well for 5- 10 Min at 600-900 rpm .

3. Adj ust the consistency to required level using resin and solvent.

The obtained white enamel paint as per method disclosed above, displayed the following properties:

Physical properties of B13 as white enam el (Surface drying-80 m inutes, tack free drying- 4.3 hours, hard drying- 16 hours and gloss at 20° is 73-75, scratch hardness fails at 1200 gm) and

Physical properties of B23 as white enam el (Surface drying-70 m inutes, tack free drying- 4 hours, hard drying- 16 hours and gloss at 20° is 70-72, scratch hardness fails at 1300 gm) .

Paint showed poor flow and levelling, brush m arks, inferior gloss in B1 3 and B23. Paint film becom es brittle hence lifting observed on panel during salt spray test in both B13 and B23. Additionally the paint m ixture in both the cases upon 30 days of accelerated stability at 55°C testing lost the homogeneity and developed lum ps. Exam ple 4

Siliconized Urethane Alkyd

Synthesis and properties of base alkyd (4A) for Silicon modification Table-12 : Reagents and chemicals used for base Alkyd (4A) synthesis

Reaction vessel equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer and Dean Stark apparatus for water separation generated from the reaction, is charged with Distilled fatty acid, Mono Pentaerythritol 98% , Phthalic anhydride, Benzoic acid, mixed xylene and DBTO with the quantities as mentioned in Table- 12.

Raising the reaction temperature to 230°C

Continuing the reaction to achieve acid value below 5 mg KOH/g and Gardner viscosity C-D at 55% solid in Mineral turpentine oil and Xylene Thinning ratio- 85: 15) . The Hydroxyl value of the resulting resin is 82 mg KOH/g and average molecular weight (Mw) is 10256.

Synthesis and properties of Siliconized Alkyd ( 4B)

Table-13 : Reagents and chemicals used for siliconized Alkyd (4B) synthesis

Reaction vessel equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer is charged with resin obtained in the previous step, DBDTL and Silicon resin (Z6018) with the quantities as m entioned in Table- 13.

Raising the reaction temperature to 160- 165°C, holding temp for three hours and further continued till a constant Gardner viscosity of ( D- to E- F) is achieved

Checking the material clarity on glass plate ultimately providing clear Siliconized Alkyd resin indicating complete com patibility.

Synthesis and properties of Siliconized Urethane Alkyd ( C1 4, C24 and C34)

Table-1 4 : Reagents and chem icals used for siliconized urethane Alkyd ( 4B) synthesis

Procedure for the synthesis of Siliconized Urethane Alkyd Reaction vessel equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer is charged with resin obtained in the previous step with the quantities as m entioned in Table- 14.

Raising the batch tem perature to 75° C and adding Isophorone diisocyanate ( I PD I ) slowly ( 10- 15 m ins) in the reaction m edium followed by Mineral Turpentine oil;

Raising the reaction temperature to 105- 1 10°C and reaction continued till a constant viscosity is achieved Optionally adjusting the viscosity of the reaction mass with m ixed xylene.

Properties of Siliconized Urethane Alkyd

Table-15 : Properties of siliconized Urethane Alkyd resin (C14, C24, C34)

Evaluation and key properties in anticorrosive enamel paint-w hite shade

Thus obtained resins C14, C24, C34 from the above step were form ulated as anticorrosive enamel paint following the process as described in Example 3. Evaluation of the properties are summarized below:

Physical properties of C14 (Surface drying-85 minutes, tack free drying- 5.5 hours, hard drying- 16 hours and gloss at 20° is 75-77, scratch hardness fails at 1200 gm) .

C24 (Surface drying -70 m inutes, tack free drying- 5.3 hours, hard drying- 16 hours and gloss at 20° is 73-74, scratch hardness fails at 1200 gm) .

C34 (Surface drying -70 m inutes, tack free drying- 5.2 hours, hard drying- 16 hours and gloss at 20° is 73-74, scratch hardness fails at 1300 gm).

Although initial drying was faster but delayed was the tack free time. Gloss at 20° was still very low. After 30 days of accelerated stability at 55°C lumps were observed in the paint mixture in all the three designs. Exam ple 5

Synthesis and properties of Epoxidized Alkyd (5A)

The Epoxidized Alkyd (5A) was synthesized according to the method as described below Table-16 : Reagents and chemicals used for Epoxidized Alkyd (5A) synthesis

Same experim ental protocol as of Exam ple-3 for Epoxidized Alkyd (3A) was followed with different amounts of pentaerthritrol and phthalic anhydride quantities (as disclosed above in the table) and the resultant Epoxidized Alkyd (5A) displayed Gardner viscosity D- E at 55% solid in Mineral turpentine oil and Xylene (Thinning ratio-85: 15) . Hydroxyl value of resin is 89 mg KOH/g and average molecular weight ( Mw) is 15256.

B. Synthesis and properties of Epoxidized Silicon Alkyd ( 5 B)

Table- 17 : Reagents and chem icals used for Epoxidized Silicon Alkyd (5B) synthesis

Sim ilar reaction protocol was followed as of Example 4 Siliconized Alkyd (4B) for the synthesis of Epoxidized Silicon Alkyd (5B) wherein reaction vessel equipped with temperature controller, heating arrangem ent, inert gas purger, overhead stirrer is charged with resin obtained in the previous step, DBDTL and Silicon resin (Z6018) with the quantities as m entioned in Table- 17. Raising the reaction temperature to 160- 165°C holding it for three hours and further continued till a constant Gardener viscosity of (D- to E- F) is reached;

Checking the material clarity on glass plate ultimately providing clear Siliconized Alkyd resin indicating complete compatibility. Synthesis and properties of Epoxidized Siliconized Urethane Alkyd (5C)

The epoxidized siliconized alkyd (5B) was further reacted with isophorone diisocyanate ( I PD I ) . Three different batches were synthesized with different ratios of resin vs. isocyanate.

Table-18 : Reagents and chem icals used for Epoxidized Siliconized Urethane Alkyd (C15, C25 and C35) synthesis

General method followed for Epoxidized Siliconized Urethane Alkyd synthesis

Reaction vessel equipped with temperature controller, heating arrangement, inert gas purger, overhead stirrer is charged with resin obtained in the previous step with the quantities as mentioned in Table- 18.

Raising the batch temperature to 75° C and adding Isophorone diisocyanate ( I PD I ) slow!y ( 10- 15 mins) in the reaction medium followed by Mineral Turpentine oil;

Raising the reaction temperature to 105- 110°C and continuing the reaction till a constant viscosity is achieved.

Adjusting the viscosity of the reaction mass with m ixed xylene if required. Physical properties of C15 - Viscosity after I PDI modification is very low (T-U on Gardener scale).

C25-Batch gelled after 3 hrs.

C35- Batch gelled after 2.5 hrs.

Exam ple 6

Synthesis and properties of Epoxidized Alkyd (6A)

The Epoxidized Alkyd (6A) was synthesized according to the method as described below Table-19 : Reagents and chemicals used for Epoxidized Alkyd (6A) synthesis

Same experimental protocol as of Exam ple-3 for Epoxidized Alkyd was followed with same quantities of the reactants and the resultant Epoxidized Alkyd (6A) is having Gardner viscosity D- at 55.2% solid in Mineral turpentine oil and Xylene (Thinning ratio-85: 15). Hydroxyl value of resin is 80 mg KOH/g and average molecular weight (Mw) is 1 1456.

Synthesis and properties of Epoxidized Silicone Alkyd (6 B)

Table-20 : Reagents and chemicals used for Epoxidized Silicone Alkyd (6B) synthesis

Same protocol for manufacture of Epoxidized Silicon Alkyd as of Example 5 was followed for preparation of said Epoxidized Silicon Alkyd from Epoxidized Alkyd (6A) with two different ratios of resin and silicon resin. Both the version obtained were taken further for synthesis of Epoxidized Siliconised Urethane Alkyd (6C).

Synthesis and properties of Epoxidized Siliconised Urethane Alkyd ( C16, C26 and C36)

Table-21 : Reagents and chemicals used for Epoxidized Silicone Urethane Alkyds (C16, C26, C36) synthesis

Identical protocol as of Example-5 for synthesis of Epoxidized Siliconised Urethane Alkyd (5C) was followed for the synthesis of C16, C26 and C36.

Physical properties of Epoxidized Siliconised Urethane Alkyd are presented as follows:

C16 (% NVM-55.1 % , Viscosity of Z- on Gardener scale, Acid value 3 mg KOH/g, Average Mw 56783) , C26 (% NVM-55.2% , Viscosity of Z-Z1 on Gardener scale, Acid value 2.3 mg KOH/g, Average Mw 72727) and

C36 (% NVM-56% , Viscosity of Z1 - on Gardener scale, Acid value 2.4 mg KOH/g, Average Mw 75254) . Epoxidized Silicone Urethane Alkyds (C16, C26, and C36) as obtained from the above step were taken for form ulation to anticorrosive enamel paint-white shade. The process of form ulating into enamel paint is the same as described under Example 3.

Evaluation and key properties in anticorrosive enam el paint-w hite shade

The performance of the suitably formulated clear/ pigmented coating compositions obtained from such m ultifunctional alkyd hybrid was validated with performance characteristics such as drying, mechanical properties, corrosion resistance and weathering. All the above epoxidized siliconized urethane alkyd (C16, C26, C36 - Example 6) showed very good performance/ properties for corrosion resistance, much superior with respect to conventional urethane alkyd or epoxidized alkyd or siliconized alkyd based anti-corrosive enamel paints. Example 5 comparative vis-a-vis enabling Example 6 clearly reveals that with Example 6 hybrid resin the enamel anticorrosive paint could be form ulated to attain the desired properties.

As demonstrated above, it was surprisingly found by way of the present invention that the ratio of epoxy/ silicone/ isocyanate modification on alkyd polymer hybrid is critical in designing the high performance alkyd polymer hybrid system , together with its required thinning in stages with select solvents to attain the end Multifunctional polymer hybrid.

The epoxidized siliconized urethane alkyd of Example 6, C16 and C26 are found to be slightly better even though the silicone modifications in these are lower than the C36.

Further to the aforesaid the criticality remains in the acid value range of the base alkyd resin prior to epoxy modification which can be further grafted with other functionalities like silicone/ isocyanate. Selective acid value range (25-45 mg KOH/gm) and more preferably (25-35 mg KOH/gm) works well for the present invention. Key performance properties of these high performance alkyd polymer hybrids in anti-corrosive enamel paints are summarized below.

Very high Gloss at 20° in anti-corrosive paint category. ii. Excellent Drying and hardness of film. iii. Scratch hardness of 1300-1400 gms iv. Very fast Recoat time (can be recoated in 4-6 hours)

V, Excellent corrosion resistance after 1222 hours at low dry film thickness of 45-55 microns which is usually possible with only two component polyurethane coating system.

Exam ple 7 One pot Synthesis of Epoxidized, Silicone modified Urethane Alkyd and properties ( Repeat of Exam ple 6, C16 in one pot synthesis)

The Epoxidized, Silicone modified Urethane Alkyd was synthesized according to the method as described below

Table-22 : Reagents and chem icals used for Epoxidized, Silicone modified Urethane Alkyd synthesis

Same experim ental protocol as of Exam ple-3 for Epoxidized Alkyd was followed with same quantities of the reactants [as mentioned in above Table -22 up to item no. 7] and the resultant Epoxidized Alkyd (after thinning up to item no. 9) is having Gardner viscosity D-at 55.2% solid in Mineral turpentine oil and Xylene (Thinning ratio-85: 15) . Hydroxyl value of resin is 80 mg KOH/g and average molecular weight ( Mw) is 1 1456.

Same protocol for manufacture of Epoxidized Silicon Alkyd as of Exam ple 5 was followed for preparation of said Epoxidized Silicon Alkyd ( up to item no. 1 1 ) and further taken for synthesis of Epoxidized Siliconised Urethane Alkyd as per protocol for manufacture of Epoxidized Silicone modified Urethane alkyd as per Example 6C.

Physical properties of Epoxidized Siliconised Urethane Alkyd resin obtained from the above process are as follows: % NVM-55.1 % , Viscosity of Z-on Gardener scale, Acid value 3 mg KOH/g, Average

Mw 56783- which are same with respect to resin of C16 The multifunctional alkyd hybrid polymer of the present invention provides superior adhesion on new/old m ild steel substrate coupled with high corrosion resistance performance of min 1222 hours when applied in 2 coat at dry film thickness of 45- 60 microns (as per ASTM B 1 17 salt spray) . Normally such high corrosion resistance performance at low coating film thickness is obtained from a m ulticoat 2K epoxy / polyurethane coating compositions and not reported from a single pack air drying MTO/ white spirit soluble alkyd based coatings. Therefore multifunctional alkyd hybrid polymer architecture of the present invention is unique in respect of functionalities grafted in a single pot reaction and the corrosion resistance performance obtained from the designed molecule.

In order to increase the corrosion resistance of a metal substrate, corrosion inhibiting pigment or additive is generally used in the coating applied to the substrate. A common corrosion inhibiting pigment is strontium chromate that provides excellent corrosion resistance. However, as chromates are known to be highly toxic and carcinogenic, there has been widespread concern over the use of chromates in recent years. Thus no chromate corrosion inhibiting pigment or additive was used for the present invention.

It is thus possible for the present advancement to provide for multifunctional polymer hybrid comprising of single component urethane alkyd modified with epoxy and silicone resins which is based on grafting epoxy, silicone and urethane functionalities in the alkyd backbone, which hybrid when used as a coating composition exhibits excellent corrosion resistance. In addition single pack self priming alkyd enamel based on said high molecular weight multifunctional polymer hybrid alkyd resin of the present invention provides high corrosion resistance and weathering performance while maintaining good gloss and mechanical properties like hardness, flexibility and adhesion when combined with suitable anticorrosive pigment and corrosion inhibitor/ adhesion promoter as known in the art. Since the coating is based on only two coat application with recoat time of 6 hours, painting job advantageously can be completed in a single day. This will significantly reduce the material and application cost of the product and provide more access to consumers.

Claims

Claim s:

1 . Multifunctional polym er hybrid comprising urethane modified silicone-epoxy- alkyd hybrid resin having silicone and epoxy resins grafted onto base alkyd backbone, said grafted epoxy content being 4-6 % , said grafted silicone content being 5-8 % and urethane content being 4-6 % on alkyd solids, enabling weight average mol. wt. of 50000-70000, fast surface drying in 70-80 m in, tack free drying in 4-5 hou rs, hard drying within 16 hours and gloss at 20° 80-86, scratch hardness pass of 1300- 1400gm .

2. The Multifunctional polymer hybrid as claimed in claim 1 wherein said urethane modified silicon-epoxy-alkyd hybrid resin is a reaction product of 2- 3 wt. % polyisocyanate and 95-96 wt.% silicon-epoxy-alkyd hybrid resin having acid value in the range of 2-3 mg KOH/g; said silicon-epoxy-alkyd hybrid resin being a reaction product of 3-5 wt. % silicone resin and 95-97 wt.% epoxy alkyd resin having acid value of about 5 mg KOH/g and hydroxyl value 80-85 mg KOH/g; said epoxy-alkyd hybrid resin being a reaction product of 5-7 wt.% epoxy resin and 90-92 wt.% base alkyd resin having acid value of 25-45 mg KOH/g which is a condensation product of select fatty acid com prising : saturates C16/C18 - 5- 12% , C18: 1 - 23-30% , C18: 2 - 32-40% and C18: 3 - 20-25% and having high iodine value of 145- 160 (gm 12 / 100 gm) , and polyhydric alcohols, polybasic carboxylic acids and anhydrides thereof including aromatic carboxylic acids and anhydrides.

3. The Multifunctional polymer hybrid as claimed in claim 1 and 2 wherein said epoxy alkyd resin is thinned epoxy alkyd resin thinned with m ineral turpentine oil and xylene at thinning ratio of ratio-85: 15.

4. The Multifunctional polymer hybrid as claim ed in claims 1 -3 wherein said base alkyd resin includes fatty acid preferably distilled fatty acid in the range of 50 -52 wt.% , polyhydric alcohols preferably pentaerthritrol in the range of 19-21 wt.% , monobasic and dibasic carboxylic acid and anhydrides including arom atic analogues preferably phthalic anhydride, benzoic acid in the range of 15-23 wt.% enabling said high iodine value in the range of 145- 160 (gm 12 / 100 gm) and select acid value of 25-45 mg KOH/g and more preferably 25-35 mg KOH/gm due to free acid groups in alkyd backbone, adapted for said select epoxy-alkyd hybrid resin and said m ultifunctional polym er hybrid enabling metal corrosion protection at low film thickness and a single pack ready to use corrosion and weather resistant self- prim ing enamel.

5. The Multifunctional polymer hybrid as claimed in claims 1 -4 wherein said fatty acid com prises saturated fatty acids includes myristic, palm itic and stearic acids preferably palm itic and stearic acid alone or in m ixture; monounsaturated fatty acids includes oleic, elaidic and vacentic acids preferably oleic alone or in m ixture; bis unsaturated fatty acids includes linoleic, Linolelaidic preferably linoleic alone or in m ixture;

Tris unsaturated fatty acids preferably linolenic alone or in m ixture.

6. The Multifunctional polymer hybrid as claimed in claims 1 -5 wherein said epoxy resin includes epoxy novolac resin, preferably epoxy novolac resin with m ultifunctionalty, said silicone resin includes hydroxyl functional silicone resin preferably low molecular weight hydroxyl functional silicone intermediate, and said urethane modification to incorporate u rethane linkages into the alkyd backbone involves aliphatic/ cycloaliphatic polyisocyanate including hexam ethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate and diphenylmethane diisocyanate preferably isophorone diisocyanate and hexam ethylene diisocyanate

7. A single pot process for the synthesis of said Multifunctional polymer hybrid as claimed in claims 1 -6 comprising the steps of: a. providing base alkyd polyol resin with an acid num ber of 25-45 mg KOH /gm ; b. epoxidizing said base alkyd polyol resin with epoxy resin yielding epoxy alkyd hybrid resin with acid value of < 5 and hydroxyl value 80-90 mg KOH/gm ; c. siliconizing epoxy alkyd hybrid resin by reacting said epoxy alkyd resin with polysiloxane resin to obtain silicon-epoxy-alkyd hybrid resin; and d. urethane modifying silicon-epoxy-alkyd hybrid resin to incorporate urethane linkages to obtain urethane modified silicone-epoxy-alkyd hybrid resin having select acid value of < 5 mg KOH/g by reaction of said silicon-epoxy-alkyd hybrid resin with isocyanates.

8. The process for synthesis of said Multifunctional polym er hybrid as claim ed in claim 7

Wherein said step (a) involves reacting in inert atmosphere one or more polyhydric alcohols with one or more polybasic acids /acid anhydrides or aromatic analogues, hydroxycarboxylic acids and monofunctional carboxylic acids along with oils/fatty acids in presence of a catalyst and reflux solvent at a reaction temperature of 230°C till acid number of 25-45 mg more preferably 25-35 mg KOH/gm is achieved, to produce the base alkyd resin com ponent ;

Wherein said step (b) involves reacting in inert atmosphere base alkyd resin as obtained in the previous step (a) with epoxy resin at 235 °C till the acid value below 5 mg KOH/g and hydroxyl value 80-90 mg KOH/gm is reached together with Gardner viscosity D- at 55.2% solid in Mineral turpentine oil and Xylene (Thinning ratio-85: 15) ; Wherein said step (c) involves reacting in inert atmosphere by heating said epoxy alkyd hybrid resin obtained from step (b) above with polysiloxane resin in presence of a catalyst at a temperature range of 160- 165° C for about 3 hours till achieving a constant Gardner viscosity ( D- to E- F) towards clear material clarity on glass plate indicating complete compatibility of the obtained silicon-epoxy-alkyd hybrid resin;

Wherein said step (d) involves reacting under inert atmosphere said silicon-epoxy- alkyd hybrid resin in Mineral Turpentine oil through its free hydroxyls with anyone of aliphatic cycloaliphatic and arom atic polyisocyanates or their derivatives after raising tem perature of the batch to 75°C till a temperature of 105- 1 10 °C followed by adj usting viscosity with xylene to reach the values of Z-Z1 on Gardener scale, and attaining therefrom urethane modifying silicon-epoxy-alkyd hybrid resin wherein all the reactions take place in-situ in a single pot.