CLIAMS:We Claim:
1. Air drying and corrosion resistant copolymer hybrid comprising urethane-modified epoxidized alkyd resin having cardanol and/ or hydroxy ether derivative of cardanol modified alkyd.

2. Air drying and corrosion resistant copolymer hybrid as claimed in claim 1 which is epoxy resin incorporated MTO thinnable polymeric binder suitable for urethane modification.

3. Air drying and corrosion resistant copolymer hybrid as claimed in anyone of claims 1 or 2 which is a reaction product of epoxy incorporated alkyd having cardanol and /or hydroxy ether derivative of cardanol modified alkyd, and aliphatic /aromatic polyisocyanate.

4. Air drying and corrosion resistant copolymer hybrid as claimed in anyone of claims 1 to 3 that is processable to achieve desired viscosity & non volatile matter when diluted in xylene.

5. Air drying and corrosion resistant copolymer hybrid as claimed in anyone of claims 1 to 4 wherein said cardanol and/or hydroxy ether derivatives of cardanol has hydroxyl value of 100-200 mg KOH/g suitable to attain base alkyd with free carboxylic groups and acid value of 20-40 (mg KOH/g) to enable incorporation of epoxy resin in the alkyd polymer backbone.
6. Air drying and corrosion resistant copolymer hybrid as claimed in anyone of claims 1 to 5 wherein said epoxy modified alkyd with free hydroxyl groups and acid value <1mgKOH/g enable aliphatic /aromatic polyisocyanate incorporation in the alkyd polymer backbone to favour urethane-modified epoxidized alkyd.

7. Air drying and corrosion resistant copolymer hybrid as claimed in anyone of claims 1 to 6 comprising a cardanol and/ or hydroxy ether derivative of cardanol modified alkyd, which is a reaction product of cardanol and/ or hydroxy ether derivative of cardanol, drying/semi drying oils or their fatty acids, aromatic carboxylic anhydride, polyhydric alcohol, aromatic/cycloaliphatic dicarboxylic acid, and optionally monofunctional carboxylic acid.

8. Air drying and corrosion resistant copolymer hybrid as claimed in anyone of claims 1 to 7 which is soluble/thinnable by mineral turpentine oil (MTO) with solubility tolerance of urethane-modified epoxidized alkyd: MTO of minimum 1: 7 by weight and favours coating composition with 800-1100 h of ASTM B117 salt spray resistance on mild steel substrate at 90-110 micron DFT in 2 coats of application at an interval of minimum 16 h.

9. A process for manufacture of copolymer hybrid of urethane modified epoxidized alkyd as claimed in anyone of claims 1 to 8 which is a single pot process comprising the steps of:
i) providing epoxy modified alkyd by reacting cardanol and/ or hydroxy ether of cardanol modified alkyd having acid number of 20-40 mg KOH/ g with 15-25 wt% of epoxy resin on alkyd wt% at about 150 oC to about 200 oC till acid value dropped < 1mgKOH/g.
ii) reacting said epoxy modified alkyd of step (i) with 1.5-5 wt% aliphatic and aromatic polyisocyanates on alkyd wt% at about 80 °C to about l30 °C to obtain said urethane modified epoxidized alkyd therefrom.
10. A process for the manufacture of said urethane modified epoxidizedalkyd as claimed in claim 9 wherein said cardanol and/ or hydroxy ether derivative of cardanol modified alkyd is obtained by the steps of:
(i) condensing 35-50 wt% vegetable oil fatty acids having iodine value of 120-150 gI2/100g, 15-20 wt% polyhydric alcohols, 20-26 wt% dicarboxylic acid/ anhydride, 0-8% chain terminating carboxylic acid and 5-20 wt% cardanol and/or hydroxy ether derivative of cardanol (hydroxyl value:120-180 mgKOH/g) upon heating to about 170 °C to about 220 oC until an acid number of 20-40mgKOH/g to yield said cardanol modified alkyd therefrom.

11. A process for manufacture of urethane-modified epoxidized alkyd resin as claimed in anyone of claims 9 or 10comprising inert azeotropic solvents including solvents for dilution selected from xylene, aromatic and aliphatic hydrocarbons, or mixtures thereof.
12. Coating composition comprising air drying and corrosion resistant copolymer hybrid having urethane-modified epoxidized alkyd resin based copolymer hybrid having cardanol and/ or hydroxy ether derivative of cardanol modified alkyd as a polymeric binder in combination with coating ingredients suitable as "one-pack" primer for a single ready to use composition for application.
13. Coating composition as claimed in claim 12 wherein said coating ingredient include additives, anti-corrosive pigments, fillers, driers, diluents.
14. Coating composition as claimed in anyone of claims 12 or 13 passing at least 800 h salt spray test when subjected to ASTM B117salt spray resistance.
15. Coating composition as claimed in anyone of claims 12-14 that attains DFT of 90-110 micron in 2 coats with maturation time of minimum 16 h between the coats.
16. A process for the manufacture of coating composition as claimed in anyone of claims 12-15 comprising
providing a cardanol and/ or hydroxy ether derivative of cardanol-modified base alkyd by reacting cardanol and/ or hydroxy ether derivative of cardanol having hydroxyl value of 100-200 mg KOH/g with alkyd ingredients and terminating the reaction at an acid number of 20-40 mgKOH/g to thus obtain said base alkyd for further modification with epoxy resin and aliphatic / aromatic polyisocyanate to obtain therefrom said urethane-modified epoxidized alkyd; and
adding coating ingredients including additives, anti-corrosive pigments, fillers, driers, diluents to obtain coating composition therefrom.
17. Coating systems comprising primer coatings having at least 2 coat of air drying and corrosion resistant copolymer hybrid having urethane-modified epoxidized alkyd resin based copolymer hybrid having cardanol and/or hydroxy ether derivative of cardanol modified alkyd that is epoxy and urethane modified suitable as a polymeric binder for long term corrosion resistance for decorative and industrial applications.
18. Coated surfaces and panels comprising coating systems/compositions including air drying and corrosion resistant copolymer hybrid having urethane-modified epoxidized alkyd resin based copolymer hybrid having cardanol and/ or hydroxy ether derivative of cardanol modified alkyd that is epoxy and urethane modified.
19. Cardanol modified alkyd comprising a reaction product of cardanol and/ or hydroxy ether derivative of cardanol with drying/semi drying oils or their fatty acids, aromatic carboxylic acid, aromatic carboxylic anhydride and polyhydric alcohols imparting enhanced hydrophobicity to the alkyd polymer back bone resulting in improved water and corrosion resistance characteristics.
20. Cardanol modified alkyd as claimed in claim 19 including said cardanol and/ or hydroxy ether derivative of cardanol-modified alkyd with free carboxylic groups and selective acid value of 20-40 (mg KOH/g) to favour incorporation of epoxy resin in the alkyd polymer backbone.
21. Cardanol modified alkyd as claimed in anyone of claims 19 or 20 wherein said polymer backbone is capable of epoxy followed by urethane modification and having desired MTO solubility.

22. A process for the manufacture of cardanol modified alkyd as claimed in anyone of claims 19 to 21 comprising:
condensing 35-50 wt% vegetable oil fatty acids having iodine value of 120-150 gI2/100g, 15-20 wt% polyhydric alcohols, 20-26 wt% dicarboxylic acid/anhydride, 0-8% chain terminating carboxylic acid and 5-20 wt% cardanol and/or hydroxy ether derivative of cardanol (hydroxyl value:120-180 mgKOH/g) by heating to about 170 °C to about 220 oC until an acid number of 20-40mgKOH/g is attained and obtaining said cardanol modified alkyd therefrom.
23. Coating composition comprising copolymer of cardanol and/ or hydroxy ether derivative of cardanol modified alkyd as a polymeric binder in combination with coating ingredients suitable as "one-pack" primer for a single ready to use composition for application.

Dated this the 1st day of June, 2015 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)
,TagSPECI:FIELD OF THE INVENTION

The present invention provides for urethane-modified epoxidized alkyd resin as copolymer hybrid having cardanol and/or hydroxy ether derivative of cardanol incorporated alkyd polymer backbone and the related process of its synthesis. Advantageously, apart from incorporation of cardanol and/or hydroxy ether derivative of cardanol into the alkyd polymer backbone of the said resin, the same could be modified with epoxy resin followed by polyisocyanate that attains solubility in white spirit i.e. mineral turpentine oil (MTO) despite incorporating MTO insoluble epoxy resin into the polymer backbone. The process of manufacture is further selective favouring such incorporation in a manner to impart the desired MTO solubility. Most advantageously, the copolymer hybrid of said urethane-modified epoxidized alkyd achieves significantly superior corrosion resistance properties over conventionally available alkyds or other known modified alkyds while also achieving and maintaining MTO solubility that is widelypreferred for air drying alkyds or coatings derived thereof. Such copolymer hybrid thus finds end use and application in high performance anti-corrosive coating for protecting and maintaining the metal across the decorative and industrial segments. Advantageously, a cardanol-modified alkyd resin comprising a reaction product of cardanol and/ or hydroxy ether derivative of cardanol with fatty acids of drying/semi drying oils, aromatic carboxylic acid, aromatic carboxylic anhydride and polyhydric alcohol imparting enhanced hydrophobicity to the alkyd polymer back bone for improved water and corrosion resistance characteristics is also provided.

BACKGROUND ART
The corrosion of metals is an enormous economic problem. Thus, efforts to develop more efficient and environmentally compliant methods to prevent corrosion have been ongoing across the globe. Anti-corrosion coatings are applied to steel and concrete structures to provide protection from corrosive environments. Generally, coatings are employed into two major markets i.e. industrial maintenance or protective coatings applied to structures in the oil and gas lines, petrochemical, paper mill, and power generation industries, as well as to bridges, domestic steel structures, water and waste treatment plants.

The degradation of coated metal parts takes place when water and oxygen penetrate the coating film, causing the separation of the paint from the metal. When water and ions reach the polymer-metal interface, electrochemical reactions take place that lead to the appearance of rust resulted into defects such as scratches, pores, blisters or regions of the paint with reduced adhesion.
One of the way for protecting metals from corrosion consists of using anti-corrosive priming paints. A typical anti-corrosion paint formulation is composed of four main components: a binder, one or several co-solvents, barrier and active pigments and fillers, and additives. The binder constitutes the backbone of the coating system and helps to bind the pigment particles together and achieve a good adhesion of the coating to the metal surface. There are a wide variety of anti-corrosive paints in the market based on oils, alkyd, epoxy, phenolic resin, chlorinated rubber, polyurethane, organic or inorganiczinc-rich type coating compositions for decorative as well as industrial use.

In order to avoid early failure of the coating and ensure a good corrosion protection the use of a well performing binder is a must. One way to avoid or delay the corrosion process is the development of binder with improved barrier properties and adhesion to the metal surface. Approaches to achieve good adhesion between coating and metal are the incorporation of functional groups into the binder and decreasing the permeability of the polymeric film. This will prevent water and ions from penetrating through the coating and reaching the metal substrate. The barrier properties can be improved by designing binders with improved film forming properties and some of such references are being mentioned here.

Reference is drawn to CN patent no. 103755935 disclosing a method of preparation of cardanol-modified alkyd wherein cardanolwas reacted with fatty acid chloride and metal hydroxide followed by reaction with glycerin and phthalic anhydride. The cardanol-modified alkyd resin of this prior art has performance properties of heat resistance, hardness and the like but does not teach any further modifications with epoxy resin and the thinnability properties in white spirit.

KR patent no. 100783649 discloses the method for preparing a water-soluble alkyd resin and method for preparing a water-soluble clear paint by using the water-soluble alkyd resin to improve the water fastness and corrosion resistance. The method comprises the steps of mixing 1 eq. of cardanol and 0.8-1.2 eq. of maleic anhydride to prepare a cardanol derivative; adding a polyvalent alcohol, a polyvalent acid and a fatty acid to the cardanol derivative and condensation polymerizing them to prepare an alkyd resin; adding styrene, acrylic acid and a peroxide to the alkyd resin for acrylic graft polymerization; neutralizing the obtained product with an amine compound; and dispersing the obtained product in deionized water. This prior art patent thus teaches a base alkyd modification with acrylic to attain a water borne polymer.

CN 101230121 patent describes preparation method for tall oil-modified phenolic resin to improve the performance property. The resin comprises the following components according to parts by weight: 90 to 100 shares of phenol, 6 to 9 shares of tertbutyl phenol, 55 to 65 shares of formaldehyde with 37 percent content, 0.4 to 0.5 shares of oxalic acid, 30 to 40 shares of tall oil, 8 to 10 shares of colophony, and 0.1 to 0.2 shares of hexa(4-aldehyde phenoxy) cyclic triphosphonitrile. The modified alkyd of this prior art is meant for corrosion resistant coating.

CN103145965 patent describes the method of preparation for air-drying epoxy-modified alkyd to improve the heat, water, chemical and salt spray resistance. The resin comprises the following components according to parts by weight: Component A: 18-23 parts of oleic acid, 5-6 parts of pentaerythritol, 3-4 parts of 95% glycerol, 0.8 to 1.0 parts of benzoic acid, maleic anhydride 0.2-0.4 parts, 0.08-0.12 parts of antioxidant , 604 parts of epoxy 7-8, 1.0-1.2 parts of xylene composition; Component B: 11.9-12.3 parts by phthalic anhydride, xylene 1.7-1.9 parts, solvent composed of 44-48 parts.The epoxy modification of the alkyd is taught by way this prior art.

JP 03273074 discloses the epoxy-modified alkyd resin based primer for automobile mending. This prior patent describes the preparation of epoxy-modified alkyd using bis-phenol based epoxy resin, soya fatty acid, benzoic acid, glycerol and phthalic anhydride and showed the primer based on it have water and corrosion resistance (500h) property.

US patent no. 4,116,902 discloses the air drying, water soluble urethane-modified alkyd resin for anti-corrosion primers and mar-resistant topcoats. This prior patent solely focused on the method of preparation of water soluble urethane-modified alkyd resin.

WO2012/087671 discloses anti-corrosive coating composition comprising polymeric binder i.e. rosin modified alkyd, maleic resin and oxyamino phosphate of magnesium (OAPM) as anti-corrosive pigment and fillers. This patent discloses the preparation of alkyd by condensation polymerization which comprises a linseed oil polymer, raw rosin, phthalic anhydride, pentaerythritol, maleic resin and mineral oil. This prior art thus teaches another approach to reach to an anti corrosive binder and the coating prepared thereof.

CN102618148 provides a epoxy coating and a preparation method thereof. An epoxy coating, characterized in that the paint and a curing agent comprising two main parts, the main paint and a curing agent. The coating not only has excellent corrosion resistance, but also has excellent compatibility with a base material or a lower coating film, particularly an epoxy coating, a polyurethane coating, a fluorocarbon coating or an alkyd resin coating. The epoxy coating is thus directed to comprise a main paint and a curing agent, wherein the main paint contains bisphenol A epoxy resin and modifying resin for modifying the bisphenol A epoxy resin; and the curing agent contains polyamino amide and cardanol modified phenolic amine.The modified resin therein is said to be preferably selected from polyester polyols, polyurethane polymer petroleum resin, rosin resin, acrylic resin and a hydroxyl group with a branched chain of one or more. The cardanol amine curing agents are valid for two component epoxy resin chemistry unlike a single component metallic drier catalyzed air drying modified alkyd.

As apparent from the aforesaid prior arts that cardanol, phenolic, epoxy and urethane modification of alkyd resin individually whileenhances the corrosion resistance property, however, single component air-drying anti-corrosive coatings based on all such modification ofalkyd reported on the other hand so far indicatedlower anti-corrosiveperformance and related problems of MTO thinnability.

It is thus apparent from the aforesaid that to have asingle component, air-drying high performance and ready to use primer paint that is corrosion resistant as well as MTO thinnable to find end use and application in decorative paint market, is a challenge in the art, and hence it is important to make provisions to achieve the same such that the primer thus attained would also have higher flash pointin addition to MTO thinnability and corrosion resistance properties, to be a low cost, relatively low odor alternative with increased flexibility at users’ end.

OBJECTS OF THE INVENTION

It is thus the basic object of the present invention to provide for a single component air-drying anti-corrosive coatings comprising urethane-modified epoxidized alkyd resin involving copolymer hybrid of cardanol and/ or hydroxy ether derivative of cardanol based alkyd with epoxy and polyisocyanate modifications and process for the synthesis of the same.
It is another object of the present invention to provide for said cardanol and/or hydroxy ether derivative of cardanol modified alkyd suitable for subsequent epoxy and polyisocyanate modifications and a process of synthesis thereof.
It is another object of the present invention to provide for said urethane-modified epoxidized alkyd resin that would impart the desired MTO solubility of said resin at resin: MTO of at least 1: 7 by weight to attain good dilution at the time of application and to facilitate proper cleaning of the applicator without sacrificing the corrosion resistance properties. It is yet another object of present invention to provide for said single component, air drying anti-corrosive pigment based primer composition involving said copolymer hybrid/ alkyd, which provides at least 800-1100 h of ASTM B117 salt spray resistance on mild steel substrate at 90-110 micron dry film thickness (DFT)in 2 coats of paint application at an interval of min 16 h.
It is another object of the present invention to provide for said urethane-modified epoxidized alkyd resin involving copolymer hybrid of cardanol and/ or hydroxy ether derivative of cardanol based alkyd with epoxy and polyisocyanate modifications that would be soluble in MTO despite incorporating MTO insoluble epoxy resin into the polymer backbone as is widely preferred for air drying alkyds or coatings derived thereof.
It is yet another object of the present invention to provide for said resin and coating compositions thereof that would have higher flash point in addition to MTO thinnability and corrosion resistance properties to be thus a low cost, relatively low odor alternative with increased flexibility at users’ end.

It is still another object of the present invention to provide for said resin and coating compositions comprising the same to find end use and application in high performance anti-corrosive coating for protecting and maintaining the metal across the decorative and industrial segments.

It is yet another object of the present invention to provide for said process of manufacture of said resin which when modified with epoxy resin followed by polyisocyanate is soluble in MTO despite incorporating MTO insoluble epoxy resin into the polymer backbone, which epoxy resin together with polyisocyanate is incorporated in such a manner thatselectively imparts the desired MTO solubility to the resin as well as achieves significantly superior corrosion resistance properties.

SUMMARY OF THE INVENTION

Thus according to the basic aspect of the present invention there is provided an air drying and corrosion resistant copolymer hybrid comprising urethane-modified epoxidized alkyd resin having cardanol and/ or hydroxy ether derivative of cardanol modified alkyd.

Preferably said air dryingand corrosion resistant copolymer hybrid which is epoxy resin incorporated MTO thinnable polymeric binder suitable for urethane modification.

More preferably said air drying, and corrosion resistant copolymer hybrid is providedwhich is a reaction product of epoxy incorporated alkyd having cardanol and /or hydroxy ether derivative of cardanol modified alkyd, and aliphatic /aromatic polyisocyanate.

Advantageously, said air drying and corrosion resistant copolymer hybrid of the present invention is processable to achieve desired viscosity & Non volatile matter when diluted in xylene.
According to another preferred aspect of the present invention there is provided said air drying and corrosion resistant copolymer hybrid wherein said hydroxy ether derivatives of cardanol has hydroxyl value of 100-200 mg KOH/g suitable to attain base alkyd with free carboxylic groups and acid value of 20-40 (mg KOH/g) to enable incorporation of epoxy resin in the alkyd polymer backbone.

According to yet another preferred aspect of the present invention there is provided said air drying and corrosion resistant copolymer hybrid wherein said epoxy modified alkyd with free hydroxyl groups and acid value <1mgKOH/g enable aliphatic /aromatic polyisocyanate incorporation in the alkyd polymer backbone to favour urethane-modified epoxidized alkyd.
Preferably, said air drying and corrosion resistant copolymer hybrid comprises a cardanol and/ or hydroxy ether derivative of cardanol modified alkyd, which is a reaction product of cardanol and/ or hydroxy ether derivative of cardanol, drying/semi drying oils or their fatty acids, aromatic carboxylic anhydride, polyhydric alcohol aromatic/cycloaliphatic dicarboxylic acid, and optionally monofunctional carboxylic acid.

Most advantageously, saidair drying and corrosion resistant copolymer hybrid is soluble/thinnable by mineral turpentine oil (MTO) with solubility tolerance of urethane-modified epoxidized alkyd: MTO of minimum 1: 7 by weight and favours coating composition with 800-1100 h of ASTM B117 salt spray resistance on mild steel substrate at 90-110 micron DFT in 2 coats of application at an interval of minimum 16 h.

It is thus a finding of the present invention that a copolymer hybrid of urethane-modified epoxidized alkyd involving cardanol and/or hydroxy ether derivative of cardanolincorporated base alkyd could be further modified with epoxy resin and polyisocyanate favouring air-drying anticorrosive coating compositions. The said copolymer relates to the incorporation of cardanol and/ or hydroxy ether derivative of cardanol into thebase alkyd backbone wherein the partial incorporation of hydroxy ether derivative of cardanol imparts hydrophobicity due to long alkyl chain at meta position resulting in improved corrosion resistance and is yet MTO soluble despite incorporation of insoluble epoxy resin into the polymer backbone and is also resistant to premature gelation. Further the hydroxy ether derivative of cardanol having primary alcoholic OH group reacts faster with carboxylic acids as compared to the phenolic OH of cardanol thereby leading to quick incorporation of the former into the base alkyd back bone resin vis-à-vis cardanol. It is also important to mention here that such modification of base alkyd with cardanol and/ or hydroxy ether derivative of cardanol and utilizing this further for epoxy and urethane modification to synthesize such a hybrid polymer molecule enabled achievement of significantly higher corrosion resistance performanceover conventionally available alkyds or other known modified alkyds while also achieving and maintaining MTO solubility of said resin at resin: MTO of at least 1: 7 by weight that is widely preferred for air drying alkyds or coatings derived thereof to attain a good dilution at the time of application in the complete absence of any premature gelation and subsequently also facilitating easy cleaning of the applicator. While the MTO tolerance of at least 1:7 could be attained together with superior corrosion resistance properties bythe copolymer hybrid of urethane-modified epoxidized alkyd of the present invention, the said resin could only be selectively achieved by cardanol and/ or hydroxy ether derivative of cardanolmodified base alkyd with free carboxylic groups and selective acid value of 20-40 (mg KOH/g) favouringfurther incorporation of epoxy resin and polyisocyanate in the alkyd polymer backbone.

The present invention in addition also provides for a process of manufacture in one potthat is selective in favouring such incorporation of MTO insoluble epoxy resin in the said alkyd in a manner to impart the desired MTO solubility. Most advantageously, the copolymer hybrid of said urethane-modified epoxidized alkyd achieves significantly superior corrosion resistance properties to find end use and application in high performance anti-corrosive coating for protecting and maintaining the metal across the decorative and industrial segments.

Importantly, in another aspect of the present invention, incorporation of epoxy resin into the said cardanol and/ or hydroxy ether derivative of cardanol-modified alkyd could be achieved due to termination of alkyd synthesis at specific acid valueas well as reacting epoxy resin atspecific time and temperature, necessary to achieve the desired MTO solubility as well as to prevent premature gelation. Thereafter resultant epoxy modified alkyd having free hydroxyls was further reacted with aliphatic / aromatic polyisocyanate preferably toluene diisocyanate (TDI) to get urethane-modified epoxidized alkyd.
In accordance with the aspects of the present invention, urethane-modified epoxidized alkyd resin prepared by the process comprises:
1) a step of forming a hydroxy ether derivative of cardanol-modified alkyd having 20-40 acid value (mgKOH/g) by reacting hydroxy ether derivative of cardanolwithdrying/semi drying oils or their fatty acid, aromatic carboxylic acid, aromatic carboxylic anhydride and polyhydric alcohols etc.
2) a step of forming epoxidized alkyd by reacting formed hydroxy ether derivative of cardanol-modified alkyd with epoxy resin (15-40 Wt% epoxy modification on alkyd content) at elevated temperature to achieve acid value less than 1mgKOH/g.
3) a step of forming urethane-modified epoxidized alkyd by further reacting epoxidized alkyd with polyisocyanate (1-5 Wt% urethane modification on alkyd content) at elevated temperature.

According to another aspect of the present invention there is provided a process for manufacture of copolymer hybrid of urethane modified epoxidized alkyd which is a single pot process comprising the steps of:
i) providing epoxy modified alkyd by reacting cardanol and/ or hydroxy ether of cardanol modified alkyd having acid number of 20-40 mg KOH/ g with 15-25 wt% of epoxy resin on alkyd wt% at about 150 oC to about 200oC till acid value dropped < 1mgKOH/g;
ii) reacting said epoxy modified alkyd of step (i) with 1.5-5 wt% aliphatic and aromatic polyisocyanates on alkyd wt% at about 80 °C to about l30 °C to obtain said urethane modified epoxidized alkyd therefrom.
Preferably a process for the manufacture of said urethane modified epoxidized alkyd is provided wherein said cardanol and/ or hydroxy ether of cardanol modified alkyd is obtained by the steps of
(i) condensing 35-50 wt% vegetable oil fatty acids having iodine value of 120-150 gI2/100g, 15-20 wt% polyhydric alcohols, 20-26 wt% dicarboxylic acid/ anhydride, 0-8% chain terminating carboxylic acid and 5-20 wt% cardanol and/or hydroxy ether derivative of cardanol (hydroxyl value:120-180 mgKOH/g) upon heating to about 170 °C to about 220 oC until an acid number of 20-40 mgKOH/g to yield said cardanol modified alkyd therefrom.

According to another preferred aspect of the present invention there is provided said process for manufacture of urethane-modified epoxidized alkyd resin comprising inert azeotropic solvents including solvents for dilution selected from xylene, aromatic and aliphatic hydrocarbons, or mixtures thereof.
According to another aspect of the present invention a coating composition is provided comprising air drying and corrosion resistant copolymer hybrid having urethane-modified epoxidized alkyd resin based copolymer hybrid having cardanol and/ or hydroxy ether derivative of cardanol modified alkyd as a polymeric binder in combination with coating ingredients suitable as "one-pack" primer for a single ready to use composition for application.
Preferably in said coating composition the coating ingredient includes additives, anti-corrosive pigments, fillers, driers, diluents.

According to another preferred aspect of the present invention there is provided said coating composition passing at least 800 h salt spray test when subjected to ASTM B117salt spray resistance.
Preferably said coating composition attains DFT of 90-110 micron in 2 coats with maturation time of minimum 16 h between the coats.
According to yet another preferred aspect of the present invention there is provided said process for the manufacture of coating composition comprising:
providing a cardanol and/ or hydroxy ether derivative of cardanol-modified base alkyd by reacting cardanol and/ or hydroxy ether derivative of cardanol having hydroxyl value of 100-200 mg KOH/g with alkyd ingredients and terminating the reaction at an acid number of 20-40 mgKOH/g to thus obtain said base alkyd for further modification with epoxy resin and aliphatic / aromatic polyisocyanate to obtain therefrom said urethane-modified epoxidized alkyd; and
adding coating ingredients including additives, anti-corrosive pigments, fillers, driers, diluents to obtain coating composition therefrom.

According to another aspect of the present invention there is provided coating systems comprising primer coatings having at least 2 coats of air drying and corrosion resistant copolymer hybrid having urethane-modified epoxidized alkyd resin based copolymer hybrid having cardanol and/or hydroxy ether derivative of cardanol modified alkyd that is epoxy and urethane modified suitable as a polymeric binder for long term corrosion resistance for decorative and industrial applications.

According to yet another aspect of the present invention coated surfaces and panels are provided comprising coating systems/compositions including air drying and corrosion resistant copolymer hybrid having urethane-modified epoxidized alkyd resin based copolymer hybrid having cardanol and/ or hydroxy ether derivative of cardanol modified alkyd that is epoxy and urethane modified.

According to another aspect of the present invention there is provided cardanol modified alkyd comprising a reaction product of cardanol and/ or hydroxy ether derivative of cardanol with drying/semi drying oils or their fatty acids, aromatic carboxylic acid, aromatic carboxylic anhydride and polyhydric alcohols imparting enhanced hydrophobicity to the alkyd polymer back bone resulting in improved water and corrosion resistance characteristics.

Preferably said cardanol-modified alkyd including said cardanol and/ or hydroxy ether derivative of cardanol-modified alkyd with free carboxylic groups and selective acid value of 20-40 (mg KOH/g) to favour incorporation of epoxy resin in the alkyd polymer backbone.

More preferably, in said cardanol-modified alkyd said polymer backbone is capable of epoxy followed by urethane modification and having desired MTO solubility.

According to another preferred aspect of the present invention a process for the manufacture of cardanol-modified alkyd is provided comprising:
condensing 35-50 wt% vegetable oil fatty acids having iodine value of 120-150 gI2/100g, 15-20 wt% polyhydric alcohols, 20-26 wt% dicarboxylic acid/ anhydride, 0-8% chain terminating carboxylic acid and 5-20 wt% cardanol and/or hydroxy ether derivative of cardanol (hydroxyl value:120-180 mgKOH/g) by heating to about 170 °C to about 220 oC until an acid number of 20-40mgKOH/g is attained and obtaining said cardanol modified alkyd therefrom.
According to another aspect of the present invention a coating composition is provided comprising copolymer ofcardanol and/ or hydroxy ether derivative of cardanol modified alkyd as a polymeric binder in combination with coating ingredients suitable as "one-pack" primer for a single ready to use composition for application.
According to another aspect of the present invention, Urethane-modified epoxidized alkyd resin is suitable for primer coating composition having anti-corrosive pigments, additives, fillers, driers and solvents as other ingredients.
Typically such coating compositions can be designed and applied to achieve DFT of 90-110 micron in 2 coats in order to meet various end application requirement. These coatings are meant for priming various ferrous, non-ferrous and chemical treated substrates such as degreasing, iron/zinc phosphating etc. Suitable application equipment’s for the application of such coating are brush, roller, air spray, airless spray or electrostatic spray etc.
Epoxy modification of alkyd followed by urethane modification has resulted into significant improvement of water and corrosion resistance of an alkyd and enhanced the salt spray resistance i.e. 800-1100h at DFT of 90-110 micron which is uncommon for an MTO thinnable conventional alkyd / modified alkyd.
This urethane-modified epoxidized alkyd resin based primer paint can be used as air-drying high performance anti-corrosive coating for protecting the various metallic substrates.

DETAILED DESCRIPTION OF THE INVENTION

As discussed hereinbefore, the present invention provides for high performance anti-corrosive and MTO thinnable, urethane-modified epoxidized alkydresin as copolymer hybrid involving cardanol and/ or hydroxy ether derivative of cardanol incorporated base alkyd polymer backbone, which base alkyd is further modified with epoxy and polyisocyanate. A one pot synthetic methodology is also provided.
Advantageously, apart from incorporation of cardanol and/ or hydroxy ether derivative of cardanol into the base alkyd of the said resin, the same has been further modified with epoxy resin followed by polyisocyanate that is soluble in MTO despite incorporating MTO insoluble epoxy resin into the polymer backbone providing for superior corrosion resistant properties. The process of manufacture is further selective favoring such incorporation in a manner to impart the desired MTO solubility in the complete absence of any premature gelation. Most advantageously, the copolymer hybrid of said urethane-modified epoxidized alkyd achieves significantly superior corrosion resistance properties over conventionally available alkyds or other known modified alkyds while also achieving and maintaining MTO solubility that is also resistant to premature gelation to be thus widely preferred for air drying alkyds or coatings derived thereof. Such copolymer hybrid thus finds end use and application in high performance anti-corrosive coating for protecting and maintaining the metal across the decorative and industrial segments.
In an embodiment of the present invention the process steps comprises of the following
In step 1, cardanol and/ or hydroxy ether derivative of cardanol-modified alkyd was prepared by reacting hydroxy ether derivative of cardanol with drying/semi drying oils or their fatty acids, aromatic carboxylic acid, aromatic carboxylic anhydride and polyhydric alcohols. Such modified alkyd modified by the hydroxy ether derivative of cardanol imparted the desired hydrophobicity to the polymer back bone and therefore enhanced water and corrosion resistance in combination with subsequent reactions with epoxy and polyisocyanate.

In step 2, the said cardanol and/ or hydroxy ether derivative of cardanol-modified alkyd was terminated at a selective acid value of 20-40 (mg KOH/g) during synthesis and such selective acid value based free carboxylic groups were used to incorporate epoxy resin into the polymer backbone through esterification reaction. Epoxy modification is well known for its improved adhesion and superior corrosion resistance properties. Incorporation of epoxy resin into the alkyd backbone and to the extent as carried out in the present invention enabled achievement of desired objectives of MTO solubility despite incorporation of MTO insoluble epoxy resin and stable copolymer could be achieved preventing premature gelation. Further a selective amount of epoxy resin for epoxy resin incorporation into the alkyd as well as the time, temperature and acid value during copolymerization with the alkyd resin favoured a resin with enhanced corrosion resistance of the copolymer.

In step 3 of the synthesis, above designed copolymer was further strengthened. This was done by partially reacting free hydroxyl groups present in the said epoxy modified alkyd with aliphatic / aromatic polyisocyanate preferably toluene diisocyanate while ensuring a stable urethane modified epoxidized alkyd in respect of accelerated stability at 55°C for 21 days. This resulted into urethane linkage into the polymer backbone thereby enhancing drying, mechanical properties and water / corrosion resistance performance.
In this copolymer hybrid, hydroxyl ether derivative of cardanol, epoxy and isocyanateincorporated resin thus synergizes to provide for anti-corrosive property together with the desired MTO solubility and flexibility.
Hence,the MTO thinnable urethane-modified epoxidized alkyd resin for long term salt spray resistance to the extent of at least 800 hatDFT of 90-110 micron in 2 coats at an interval of minimum 16 h is unique and is thus a special finding of the present invention.
For purposes of the following detailed description, it is to be understood that the present invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about".
Corrosion is commonly defined as a chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the metal and its properties. The process of corrosion is an anodic reaction process, whereby metal-dissolving ions are generated into insoluble corrosion products, such as rust.
Metal or metallic is defined herein as any substance susceptible to corrosion.
The coating compositions of the present invention have broad utility for protecting metallic substrates susceptible to corrosion, including ferrous substrates such as iron [Fe] and steel as well as Aluminum[Al] ,Copper [Cu], Magnesium [Mg] , and alloys thereof as well as other conventional metals employed in any structural applications. This includes beams, columns, grills, shutters, window frames or any other metallic articles of utility, where corrosion may occur due to contact by atmospheric moisture, water, salinity, humidity or other corrosives normally present in urban or industrial environments. Therefore, although it will be appreciated by those skilled in the art that the coating composition of the present invention may be applied to any type of metallic substrate, it is especially suited for use on preferably ferrous surfaces and will be described in connection therewith. The present invention relates to coating compositions for providing corrosion resistance on metallic substances used in decorative as well as industrial segments.
The composition of the present invention is essentially a "one-pack" primer which means all the necessary ingredients are composed in a single ready to use composition for application.
The present invention is directed to metal as a primer coating composition comprising a resin, filler and an anti-corrosive pigment especially designed for decorative,general industrial and auto refinish market.
One of the principle aspects of the present invention relates to develop a polymeric binder for primer coating composition comprising a urethane-modified epoxidized alkyd resin with metallic driers.The urethane-modified epoxidized alkyd composition according to the invention will be described in detail. The urethane-modified epoxidized alkyd is prepared in three steps in single pot as follows;
In first step of forming the alkyd resin of this invention, vegetable oils or their fatty acids, cardanol and/or hydroxy ether derivative of cardanol, an aromatic/cycloaliphatic carboxylic acid, aromatic dicarboxylic acid or anhydride reacted with an excess of polyhydric alcohol were employed.
Vegetable oil fatty acids suitable for use in the practice of this invention include aliphatic, unsaturated fatty acids or mixtures thereof, such as oleic, linoleic, or linolenic acid coming from natural vegetable oil based origin. Preferred acids include, but are not limited to, soybean fatty acid, dehydrated castor oil fatty acid, tung oil fatty acid, linoleic acid, tall oil fatty acid and linseed oil fatty acid etc. Fatty acids having iodine value of 130-180 gI2/100g are particularly preferred. The amount of vegetable oil acid used is generally from about 30-55% by weight, preferably 36-48% based on total ingredients. Although customized vegetable oil fatty acid (approximate fatty acid composition %: up to C16 = 7; C18:0 = 3;C18:1 = 27; C18:2 =39; C18:3 =23; C20 =0.5) having iodine value of 140-155 gI2/100g is preferred for the present invention.However,soybean fatty acid, linseed oil fatty acid or dehydrated castor oil fatty acid, niger seed oil fatty acid, tobacco seed oil fatty acid, cotton seed oil fatty acid, rubber seed oil fatty acid or any other drying / semi drying oil fatty acidscan also be used. Suitable aromatic dicarboxylic acids or anhydrides thereof include isophthalicacid, terephthalic acid, phthalic anhydride or other aromatic or cycloaliphatic acid anhydride as such or in combination, but the preferred one is phthalic anhydride. The amount of aromatic dicarboxylic acid can vary from 18-30% of total ingredients, preferably 21-26% based on total ingredients. Suitable mono functional carboxylic acids including, benzoic acid, abietic acid (Rosin), cyclohexane carboxylic acid may be used as chain terminator, but preferred one is benzoic acid. The amount of aromatic carboxylic acid can vary from 0-15% of total ingredients, preferably 0-8% based on total ingredients.
Phthalic anhydride is preferably used as dibasic acid for alkyd synthesis apart from Isophthalic acid. In the present invention Phthalic anhydride has been preferred over other carboxylic acids/ anhydrides in order to make the resin economically viable to manage the reactivity during synthesis and storage stability of the resin. Maleic anhydride on the other hand results in the generation of unstable polymer leading to premature gelation.

Cardanol and /or hydroxy ether derivatives of cardanol are available commercially and may be used as modifier to improve functional properties. Chemical formula of hydroxy ether derivatives of cardanolis as given below:

Cardanol/Hydroxy ether derivatives of cardanol having hydroxyl value of 100-200 mg KOH/g is suitable for this invention, the preferred hydroxyl value is 120-170 mg KOH/g. It is used in amounts of about 5-20%, but 7-15% is preferred.

The polyols suitable for the practice of this invention include polyhydric alcohols having two or more hydroxyl groups per molecule. There are many polyols known in the art, or mixtures thereof, such as trimethylpentanediol, diethylene glycol, neopentylglycol, glycerol, pentaerythritol, trimethylolethane, trimethylol propane and the like. In this invention, pentaerythritol is used as polyol in amount of 14-25%, preferably16-21% based on total ingredients.

In the first step, alkyd portion of the resin is prepared by charging the vegetable fatty acid, pentaerythritol, phthalic anhydride, benzoic acid, cardanol and/or hydroxy ether derivative of cardanol and mixed xylene as azeotropic solvent into a reaction vessel. Reaction vessel is equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly. The reaction charge is heated at 170 °C for 1 h and thereafter reaction temperature is increased from 170 to 220oCin 4-6 h until an acid number of 20-40mgKOH/g is obtained.The mixture is cooled to about 150 °C.
In the second step of forming epoxy modified alkyd, base alkyd synthesized in the first stage is reacted with epoxy resin. Epoxy resins suitable for use in the practice of this invention include, diglycidyl ether of Bis-phenol A (DGEBA), diglycidyl ether of Bis-phenol F, epoxy novolacs, cycloaliphatic epoxy and the like. In this invention, DGEBA (epoxy equivalent weight 180-195) is used. The amount of epoxy resin can vary from 10-40% on alkyd content, preferably 15-25 % on alkyd content. During epoxy modification of alkyd, liquid epoxy was added into alkyd resin at 150 °C under stirring. The reaction mixture is heated from 150-200 °C in 2-3 h until acid number dropped to <1mgKOH/g. The reaction mixture is cooled down to 80 °C.

In the third step of forming urethane-modified epoxidized alkyd, epoxidized alkyd prepared in second stage is reacted with an aliphatic or aromatic polyisocyanate or their pre-polymers, preferably aromatic diisocyanate e.g. toluene diisocyanate. In this invention the amount of TDI can vary 1.5-5% on alkyd content, preferably 2-4% on alkyd content.During urethane modification of epoxidized alkyd, TDI is added slowly into epoxidized alkyd at 80°C over the period of 20-30 minutes. After completeaddition of TDI, the reaction mixture is heated for an additional 2-3 h at l00-l30°C. Then reaction is cooled to 80°C and 0.5% of n-Butanol is added into reaction mixture.
In one of the embodiments of present invention metallic driers are employed to accelerate the conversion of coating into cross linked dry film through auto oxidative polymerization. Driers are primarily heavy metal soaps of organic acids. Some of the preferred drier combinations employed in context with the present invention are selected from the group comprising:
1) Cobalt Octoate: Acts as a "Surface Drier ". It is primarily an oxidation catalyst and an optimum quantity need to be used to avoid surface wrinkling.
2) Manganese Octoate: It has both oxidizing and polymerizing properties and produce hard film.
3) Zirconium Octoate: Acts as an active cross-linking agent and improves hardness of dried film as well as its adhesions.
Fillers- Inorganic fillers are solids that are present in a finely divided form in the composition. Fillers are used to bring down the cost of product, ease of application and have influence upon the rheology i.e. thickening of paint. The preferred fillers for this invention are mica, steatite, dolomite, silica, barytes etc. and amount of filler used depends upon the characteristics of filler i.e. their oil absorption, shape, size etc, particular polymeric material and property requirement of finished products.
In one of the embodiments of the present invention, the anti-corrosive pigment e.g. zinc oxide, calcium phosphate, strontium phosphosilicates, modified aluminium triphosphate, zinc molybdate, zinc phosphomolybdate, aluminium zinc phosphate, micaceous iron oxide, lead silico chromate, strontium chromate etc. ispresent in the coating composition in an amount of about 4 to 12 parts of the mixture with the parts being considered based on the total weight of the coating composition. Preferably, the anti-corrosive pigment comprises 6-10 parts based on the total weight of the coating composition.A preferred anti-corrosive pigment employed in the present coating composition is zinc phosphate.

In the paint compositions of the present invention, there may further be added, when necessary, various additives such as, rheology modifiers, dispersing agent, storage stability improving agents, antioxidants, anti-skinning and anti-settling agent etc. each in an adequate amount.

A preferred diluent/carrier is MTO and solvent naphtha (C9 aromatic hydrocarbon solvent). The proportion of diluent may vary according to the desired consistency of the paint composition.
The present invention provides coating compositions which are meant for priming various ferrous, non-ferrous and chemical treated substrates such as degreasing, iron/zinc phosphating etc. and may be easily applied by conventional application systems such as brushing, roller, spraying, sprinkling, flow coating, dipping, and the like.
The DFT of the coating is preferably 90-110 microns in 2 coats at an interval of minimum 16 h in order to meet various end application requirement.
According to a further aspect of the invention a test metal panel (cold role mild steel) coated with a control composition and a composition as per the current invention were subjected to various tests after 7 days of application to evaluate the effect on flexibility, drying time, impact resistance, scratch hardness, humidity resistance, 5% salt spray resistance, and 1 mm cross cut adhesion test. The flexibility of the coatings are tested by conducting a Mandrel bend test(ASTM D522). Scratch hardness of the coating are tested using Sheen make automatic scratch tester Ref. No. 705 with 1mm tungsten carbide tip. The 1 mm cross-cut adhesion test are carried out according to ASTM D 3359. Impact Resistance of coating are tested using Falling-Ball Method (65±0.2 cm height × 15.9± 0.08 mm diameter × 908±1 gm load).
The salt spray resistance of the coating is tested according to ASTM B117.The appearance of corrosion product is evaluated periodically and test duration depends on the corrosion resistance of the coating; the more corrosion resistant coating, longer the period in testing without showing signs of corrosion.
Primer coating compositions obtained from urethane-modified epoxidized alkyd resin can be used for priming various metallic substrates after requisite surface preparation at required DFT. Such primed substrates can be suitably over coated with MTO thinnable single pack air drying alkyd/modified alkyd based top coats to impart desired aesthetic in terms of film, gloss, colour etc. in addition to the substrate protection.
The urethane-modified epoxidized alkyd resin of the present invention has particular utility as air-drying and MTO thinnable resin for anti-corrosive primer. The following examples illustrate certain embodiment and aspects of the presentinvention and not to be construed as limiting the scope thereof. All parts and percentages are by weight basis unless otherwise stated.

Example 1
SOFA based alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Soyabean oil Fatty acid 46.0
Phthalic anhydride 21.5
Pentaerythritol (98% pure) 21.0
Benzoic acid 5.5
Mix-Xylene 6.0

Total 100

All the reactants and solvent are charged into reactor and is heated to temperature of about 160-170 °C for 1 h and thereafter reaction temperature is increased from 170 to220 oC in 4-5 h until an acid number dropped < 10mgKOH/g. The reaction mixture is cooled down to 120 °C and diluted to 60% non-volatile matter (NVM) with MTO.

Example 2
A hydroxy ether derivative of cardanol-modified alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Soyabean oil Fatty acid 36.0
Phthalic anhydride 24.0
Pentaerythritol (98% pure) 17.0
Mix-Xylene 6.0
Stage II
Hydroxy ether derivative of cardanol (OH value of approx.. 170-180 mgKOH/g) 17.0
Total 100

In stage I, all the reactants and solvent are charged into reactor and is heated to temperature of about 160-170 °C for 1 h and thereafter reaction temperature is increased from 170 to190oC in 2-3 h until an acid number of 70-80 is obtained. The mixture is cooled to about 150 °C. Then in stage II, hydroxy ether derivative of cardanolis added into reaction mixture of stage I. The reaction mixture is heated from 150-230 °C in 6-7 h until acid number dropped < 11mgKOH/g. The reaction mixture is cooled down to 120 °C and diluted to 60%NVM with MTO.

Example 3
An epoxy-modified alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Soyabean oil Fatty acid 36.6
Phthalic anhydride 17.0
Pentaerythritol (98% pure) 16.3
Benzoic acid 06.1
Mix-Xylene 06.0
Stage II
Liq. Epoxy (epoxy eq. Wt 180-195) 18.0
Total 100
In stage Iof alkyd synthesis, all the reactants and solvent are charged into reactor and is heated to temperature of about 160-170 °C for 1 h and thereafter reaction temperature is increased from 170 to220oC in 3-4 h until an acid number of 30-35 is obtained. The mixture is cooled to about 150 °C and then in stage II, liq. epoxy is added into alkyd of stage I. The reaction mixture is heated from 150-180 °C in 3-4 h until acid number dropped < 7 mgKOH/g. The reaction mixture is cooled down to 120 °C and diluted with mixed xylene to 60 % NVM. Thinning in MTO was also carried out, however, the MTO tolerance that could be achieved is only 1:4.

Example 4
A urethane-modified epoxidized alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Soyabean oil Fatty acid 23.26
Phthalic anhydride 10.8
Pentaerythritol (98% pure) 10.36
Benzoic acid 3.88
Mix-Xylene 3.8
Stage II
Liq. Epoxy (epoxy eq. Wt 180-195) 11.5
Mix-Xylene 34.5
Stage III
TDI 1.4
n-Butanol 0.5
Total 100

In stage I of alkyd synthesis, all the reactants and solvent are charged into reactor and heated to the temperature of about 160-170 °C for 1 h and thereafter reaction temperature is increased from 170 to 220 oC in 3-4 h until an acid number of 30-35 (mg KOH/g) is obtained. The mixture is cooled to about 150 °C and then in stage II, liq. Epoxy is added into alkyd of stage I. The reaction mixture is heated from 150-160 °C in 3-4 h until acid number dropped < 5 mgKOH/g. The reaction mixture is diluted with remaining mix. Xylene and allowed to cool it to 80oC.Thereafter in stage III, TDI is slowly added into reaction mixture under stirring over the period of 20-30 minutes. After complete addition of TDI, the reaction mixture is heated for about an additional 2-3 h at l00-l30°C. Then reaction is cooled to 80 °C and 0.5% of n-Butanol is added into reaction mixture.

Example 5
An urethane-modified epoxidized alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Soyabean oil Fatty acid 20.33
Phthalic anhydride 11.47
Pentaerythritol (98% pure) 9.9
Benzoic acid 3.39
Hydroxy ether derivative of cardanol (OH value of approx.. 120-130 mgKOH/g) 3.65
Mix-Xylene 3.38
Stage II
Liq. Epoxy (epoxy eq. Wt 180-195) 11.5
Mix-Xylene 34.50
Stage III
TDI 1.38
n-Butanol 0.5
Total 100

In stage I of alkyd synthesis, all the reactants and solvent are charged into reactor and heated to temperature of about 160-170 °C for 1 h and thereafter reaction temperature is increased from 170 to 220oC in 3-4 h until an acid number of 30-35 (mg KOH/gm) is obtained. The mixture is cooled to about 150 °C and then in stage II, liq. Epoxy is added into alkyd of stage I. The reaction mixture is heated from 150-200°C in 3-4 h until acid number dropped < 1 mgKOH/g. The reaction mixture is diluted with remaining mix. Xylene and allowed to cool it to 80oC. Thereafter in stage III, TDI is slowly added into reaction mixture under stirring over the period of 20-30 minutes. After complete addition of TDI, the reaction mixture is heated for about an additional 2-3 h at l00-l30 °C. Then reaction is cooled to 80 °C and 0.5% of n-Butanol is added into reaction mixture.
Example 6
A urethane-modified epoxidized alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Customized Fatty acid (Iodine value 140-160 gI2/100g) 20.33
Phthalic anhydride 11.47
Pentaerythritol (98% pure) 9.9
Benzoic acid 3.39
Hydroxy ether derivative of cardanol (OH value of approx.. 120-130 mgKOH/g) 3.65
Mix-Xylene 3.38
Stage II
Liq. Epoxy (epoxy eq. Wt 180-195) 11.5
Mix-Xylene 34.18
Stage III
TDI 1.7
n-Butanol 0.5
Total 100

In stage I of alkyd synthesis, all the reactants and solvent are charged into reactor and heated to temperature of about 160-170 °C for 1 h and thereafter reaction temperature is increased from 170 to 220oC in 3-4 h until an acid number of 30-35 (mg KOH/g) is obtained. The mixture is cooled to about 150 °C and then in stage II, liq. Epoxy is added into alkyd of stage I. The reaction mixture is heated from 150-160°C in 3-4 h until acid number dropped < 1 mgKOH/g. The reaction mixture is diluted with remaining mix. Xylene and allowed to cool it to 80 oC. Thereafter in stage III, TDI is slowly added into reaction mixture under stirring over the period of 20-30 minutes. After complete addition of TDI, the reaction mixture is heated for about an additional 2-3 h at l00-l30°C. Then reaction is cooled to 80°C and 0.5% of n-Butanol is added into reaction mixture.
Example 7
An urethane-modified epoxidized alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Customized Fatty acid (Iodine value 140-160gI2/100g) 22.9
Phthalic anhydride 11.47
Pentaerythritol (98% pure) 9.9
Hydroxy ether derivative of cardanol (OH value of approx.. 120-130 mgKOH/g) 4.47
Mix-Xylene 3.39
Stage II
Liq. Epoxy (epoxy eq. Wt 180-195) 11.5
Mix-Xylene 34.49
Stage III
TDI 1.38
n-Butanol 0.5
Total 100

In stage I of alkyd synthesis, all the reactants and solvent are charged into reactor and heated to temperature of about 160-170°C for 1 h and thereafter reaction temperature is increased from 170 to 220oC in 3-4 h until an acid number of 30-35(mg KOH/g)is obtained. The mixture is cooled to about 150 °C and then in stage II, liq. Epoxy is added into alkyd of stage I. The reaction mixture is heated from 150-200°C in 3-4 h until acid number dropped < 1 mgKOH/g. The reaction mixture is diluted with remaining mix. Xylene and allowed to cool it to 80 oC. Thereafter in stage III, TDI is slowly added into reaction mixture under stirring over the period of 20-30 minutes. After complete addition of TDI, the reaction mixture is heated for about an additional 2-3 h at l00-l30 °C. Then reaction is cooled to 80 °C and 0.5% of n-Butanol is added into reaction mixture.
Example 8
An urethane-modified epoxidized alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Customized Fatty acid (Iodine value 140-160gI2/100g) 20.33
Phthalic anhydride 12.0
Pentaerythritol (98% pure) 9.9
Hydroxy ether derivative of cardanol (OH Value of 120-130 mgKOH/g) 6.51
Mix-Xylene 3.39
Stage II
Liq. Epoxy (epoxy eq. Wt 180-195) 11.5
Mix-Xylene 34.17
Stage III
TDI 1.7
n-Butanol 0.5
Total 100

In stage I of alkyd synthesis, all the reactants and solvent are charged into reactor and heated to temperature of about 160-170°C for 1 h and thereafter reaction temperature is increased from 170 to 220oC in 3-5 h until an acid number of 30-35(mg KOH/g) is obtained. The mixture is cooled to about 150°C and then in stage II, liq. Epoxy is added into alkyd of stage I. The reaction mixture is heated from 150-170°C in 2-3 h until acid number dropped < 1 mgKOH/g. The reaction mixture is diluted with remaining mix. Xylene and allowed to cool it to 80oC. Thereafter in stage III, TDI is slowly added into reaction mixture under stirring over the period of 20-30 minutes. After complete addition of TDI, the reaction mixture is heated for about an additional 2-3 h at l00-l30 °C. Then reaction is cooled to 80°C and 0.5% of n-Butanol is added into reaction mixture.
Example 9
An urethane-modified epoxidized alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Customized Fatty acid (Iodine value 140-160gI2/100g) 21.33
Phthalic anhydride 11.47
Pentaerythritol (98% pure) 9.9
Benzoic acid 2.39
Hydroxy ether derivative of cardanol (OH value of approx.. 120-130 mgKOH/g) 3.65
Mix-Xylene 3.39
Stage II
Liq. Epoxy (epoxy eq. Wt 180-195) 11.5
Mix-Xylene 34.17
Stage III
TDI 1.7
n-Butanol 0.5
Total 100

In stage I of alkyd synthesis, all the reactants and solvent are charged into reactor and heated to temperature of about 160-170°C for 1 h and thereafter reaction temperature is increased from 170 to 220oC in 3-5 h until an acid number of 20-25(mg KOH/g)is obtained. The mixture is cooled to about 150 °C and then in stage II, liq. Epoxy is added into alkyd of stage I. The reaction mixture is heated from 150-200 °C in 2-3 h until acid number dropped < 1 mgKOH/g. The reaction mixture is diluted with remaining mix. Xylene and allowed to cool it to 80oC. Thereafter in stage III, TDI is slowly added into reaction mixture under stirring over the period of 20-30 minutes. After complete addition of TDI, the reaction mixture is heated for about an additional 2-3 h at l00-l30 °C. Then reaction is cooled to 80 °C and 0.5% of n-Butanol is added into reaction mixture.
Example 10
An urethane-modified epoxidized alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Customized Fatty acid (Iodine value 140-160gI2/100g) 22.33
Phthalic anhydride 11.47
Pentaerythritol (98% pure) 9.9
Hydroxy ether derivative of cardanol (OH value of approx.. 170-180 mgKOH/g) 3.65
Benzoic acid 1.39
Mix-Xylene 3.39
Stage II
Liq. Epoxy (epoxy eq. Wt 180-195) 11.5
Mix-Xylene 34.17
Stage III
TDI 1.7
n-Butanol 0.5
Total 100

In stage I of alkyd synthesis, all the reactants and solvent are charged into reactor and heated to temperature of about 160-170°C for 1 h and thereafter reaction temperature is increased from 170 to 220oC in 3-5 h until an acid number of 30-35(mg KOH/g)is obtained. The mixture is cooled to about 150°C and then in stage II, liq. Epoxy is added into alkyd of stage I. The reaction mixture is heated from 150-200°C in 2-3 h until acid number dropped < 1 mgKOH/g. The reaction mixture is diluted with remaining mix. Xylene and allowed to cool it to 80 oC. Thereafter in stage III, TDI is slowly added into reaction mixture under stirring over the period of 20-30 minutes. After complete addition of TDI, the reaction mixture is heated for about an additional 2-3 h at l00-l30 °C. Then reaction is cooled to 80 °C and 0.5% of n-Butanol is added into reaction mixture.
Example 11
An urethane-modified epoxidized alkyd resin is prepared by charging the following constituents into a four- necked reactor flask equipped with a temperature controller, heating mantle, nitrogen purger, overhead stirrer and Dean Stark assembly.
Ingredients Parts by Weight
Stage I
Customized Fatty acid (Iodine value 140-160gI2/100g) 22.33
Phthalic anhydride 11.47
Pentaerythritol (98% pure) 9.9
Cardanol
3.65
Benzoic acid 1.39
Mix-Xylene 3.39
Stage II
Liq. Epoxy (epoxy eq. Wt 180-195) 11.5
Mix-Xylene 35.12
Stage III
TDI 0.75
n-Butanol 0.5
Total 100

In stage I of alkyd synthesis, all the reactants and solvent are charged into reactor and heated to temperature of about 160-170°C for 1 h and thereafter reaction temperature is increased from 170 to 220oC in 3-5 h until an acid number of 30-35(mg KOH/g)is obtained. The mixture is cooled to about 150°C and then in stage II, liq. Epoxy is added into alkyd of stage I. The reaction mixture is heated from 150-200°C in 2-3 h until acid number dropped < 1 mgKOH/g. The reaction mixture is diluted with remaining mix. Xylene and allowed to cool it to 80oC. Thereafter in stage III, TDI is slowly added into reaction mixture under stirring over the period of 20-30 minutes. After complete addition of TDI, the reaction mixture is heated for about an additional 2-3 h at l00-l30°C. Then reaction is cooled to 80°C and 0.5% of n-Butanol is added into reaction mixture.
Physical properties of the designed Resins are listed in Table 1.

Anti-corrosive primer coating composition
Primer coating composition comprises; resin from examples 1-14, additives, fillers, pigments, drier and diluents.The pigment volume concentration (PVC) and %NVM of primer is 35 and 60 respectively. The primer coating composition is applied on sanded mild steel panel (1.6 × 70 × 150 mm) by brushing application and left to stand at room temperature. A 90-110 micron dry film thickness of coating is obtained in 2 coats with maturation time of 16-24 h between the 2 coats. Then after seven days of curing, these test panels are evaluated for various performance properties like flexibility, adhesion, scratch hardness, impact resistance and salt spray resistance. Test results of coatings are shown in Table 2.
Table 1. Physical properties of resins
Properties Examples
1 2 3 4 5 6
Appearance Clear Clear Clear Clear Clear Clear
Colour on Gardner scale
4-5 8-9 6-7 9-10 9-10 9-10
Acid Value (mgKOH/g)
6.5 9.2 5.9 4.5 0.7 0.5

%NVM-120°C/1 h 60 60.5 60 60.1 60 60
Viscosity on Gardner scale
Z2-Z3 Z3-Z4 M-N Z1-Z2 U-V Y-Z
MTO tolerance Infinite Infinite 1:4 1:3 1:5 1:4

Table 1. Continued
Properties Examples
7 8 9 10 11
Appearance Clear Clear Clear Clear Clear
Colour on Gardner scale
9-10 9-10 9-10 9-10 9-10
Acid Value (mgKOH/g)
0.4 0.3 0.5 0.2 0.7
%NVM-120°C/1h 61 61 60 61 61.1
Viscosity on Gardner scale Y-Z Z1-Z2 X-Y Z-Z1 Z1-Z2
MTO tolerance 1:20 1:12 1:10 1:9 1:7

Table 2. Primer Coating composition test results
Coating compositions with resin from Examples
1 2 3 4 5 6
DFT (microns) 100 100 100 100 100 100
Surface dry time (min) 30 30 50 40 65 45
Tack free time (h) 6 4.5 6.5 5.5 7 5.5
Hard dry time (h) 24 24 24 24 24 24
Scratch hardness after 48 h (g) 1000 1300 1000 1100 1000 1200
Flexibility Pass Pass Pass Pass Pass Pass
Impact resistance Pass Pass Pass Pass Pass Pass
Adhesion Good Excellent Good Good Ordinary Excellent
Salt Spray Test (h) 150 250 400 600 750 1100

Table 2. Continued
Coating compositions with resin from Examples
7 8 9 10 11
DFT (microns) 100 100 100 100 100
Surface dry time (min) 55 45 60 50 45
Tack free time (h) 7 6 6 7 5.5
Hard dry time (h) 24 24 24 24 24
Scratch hardness after 48 h (g) 1100 1200 1100 1000 1000
Flexibility Pass Pass Pass Pass Pass
Impact resistance Pass Pass Pass Pass Pass
Adhesion Ordinary Good Good ordinary Ordinary
Salt Spray Test (h) 650 1000 900 500 400

It is thus possible by way of the present advancement to provide for air drying and corrosion resistant copolymer hybrid comprising urethane-modified epoxidized alkyd resin having cardanol and/or hydroxy ether derivative of cardanol incorporated alkyd polymer backbone and the related process of its synthesis. Said alkyd resin apart from being modified with cardanol and/or hydroxy ether derivative of cardanol is also further modified with epoxy resin followed by polyisocyanate that is soluble in MTO despite incorporating MTO insoluble epoxy resin into the polymer backbone with solubility tolerance of urethane-modified epoxidized alkyd: MTO of at least 1: 7 by weight to attain a good dilution at the time of application in the complete absence of any premature gelation and subsequently also facilitating easy cleaning of the applicator and also favours corrosion resistance coating compositions with 800-1100 h of ASTM B117 salt spray resistance on mild steel substrate at 90-110 micron DFT in 2 coats.
The process of manufacture of said copolymer hybrid is further selective favoringincorporation of such epoxy, diisocyanate in the modified alkyd in a manner to impart the desired MTO solubility and corrosion resistance properties. Most advantageously, the copolymer hybrid of said urethane-modified epoxidized alkyd achieved significantly superior corrosion resistance properties over conventionally available alkyds or other known modified alkyds while also achieving and maintaining MTO solubility that is widely preferred for air drying alkyds or coatings derived thereof. Such copolymer hybrid thus finds end use and application in preparing high performance anti-corrosive coating for protecting and maintaining the metal across the decorative and industrial segments.