TITLE: An anticorrosion and water repellent coating formulation for coating on galvanized steel
FIELD OF THE INVENTION
The invention refers to the synthesis of different water and solvent based coating solution for the corrosion resistance. It comprises the steps of: i. providing linseed and rung oil modified aclin resins ii. providing polar solvents/water for lowering the viscosity of the solution iii. providing flexibilizers/adhesion promoter iv. providing thixotropic agent and dissolution agents, if uses water as a diluent v. putting altogether into a vessel and stirring at 400 rpm for 30 minutes vi. applying as-obtained solution on metallic surface either by spraying, dipping or brushing and leave it for 10 to 300 seconds for its curing at 27oC vii. providing excellent corrosion resistance and hydrophobic properties.
BACKGROUND OF INVENTION
An unavoidable phenomenon of corrosion can be delayed by providing oil/grease, polymeric coatings, by inserting some corrosion pigments /additives which provide protection to a metal surface by shielding it from humid atmosphere. But in high humid conditions, protective barrier deteriorates because of the creation of creep under the coated film
Corrosion inhibitors form a protective layer by adsorbing on the metal's surface. These inhibitors are dispersing into the solution via some dispersion techniques and reduced the corrosion rate by interfering to the anodic/cathodic reaction either by adsorbing of ions/molecules onto the metal surface, increasing the hydrophobic properties, decreasing the diffusion rate for reactants to the metal surface or formation of a passive layer which can be assessed by polarization studies.

We are introducing various types of coating formulations containing various inhibitors with couple of oil modified aclin resins (linseed oil and tung oil modified aclin resin) which are natural bio-adhesives, non-toxic and amorphous edible resin and scratched from sub-fossils deposits. It can be used in forming synthetic polymers, lacquers and varnishes. Both oil modified aclin resins are soluble in alcohols and methylated spirits and it becomes tacky when a drop of a solvent is placed on it. Often, they are insoluble in water but can be prepared by using milder alkalis, ammonia, borax and sodium based reducing agent. These solutions can be applied even at low temperatures and easily be touched up if it is scratched. It dries within a minutes. These resins are used as a film forming agent in coating solution. Apart from film formation, they provide corrosion resistance and hydrophobicity. It was used to protect some military rifle stocks, galvanized iron threads and in plumbing applications.
BRIEF DESCRIPTION OF THE INVENTION
US 2358475 discloses modified plasticizers, drying oil and coating compositions. In this invention, 1 to 10 weight % of diisocyanate or diisothiocyanate modifier is mixed into the paint/enamel according to the type of drying oil composition. Then the formed layer of coating is evaluated by quick rapid rate of set-up than unmodified films which is cured by the air-drying or heat drying. These coating compositions are mostly being used for floor and wall covering.
US 4442256 A describes, an additive for alkyd resin coating formulation which is a mixture of an isocyanate isocyanurate, dibutyltindilaurate and an organic solvent. This composition is mostly usable in automobiles sectors due to its excellent gloss retention on weathering and hardness.

US 4179420 reveals oil-modified polyesters and oil-free polyesters which are easily dispersed in water. These are the blend of aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and polyols. By this reference, the polyester (formed by maleic anhydride or trimellitic anhydride) can be water soluble by adding of an amine, a metal oxide, hydroxide or carbonate.
US 4525524 A reveals a water-dispersible polyester formed by repeat units such as (a) a diacid component comprised of 20 to 90 mole % of group consisting of dimethylterephthalate and terephthalic acid, 1 to 6 mole % of an organic sulfonic acid monomer and 4 to 74 mole % of group consisting of alkyl dicarboxylic acids, 6 to 38 carbon atoms containing diesters of alkyl dicarboxylic acids, 9 to 20 carbon atoms containing aryl dicarboxylic acids, 11 to 22 carbon atom containing diesters of aryl dicarboxylic acids and diesters of alkyl substituted aryl dicarboxylic acids, 9 to 20 carbon atoms containing alkyl substituted aryl dicarboxylic acids, dimethylorthophthalate, dimethylisophthalate, orthophthalic acid, and isophthalic acid; and (b) a diol component comprised of 20 to 100 mole % ethylene glycol, and 0 to 80 mole % of group consisting of 3 to 12 carbon containing glycols and 4 to 12 carbon atoms containing glycol ethers. They are specifically usable for adhering aluminum foils to polyethylene terephthalate films.
US 4401787 A describes polyester latex formulations which are loaded with a hydrophobe comprised of about 0.5 to 5.0 mole % dicarboxylic acid which is derived by repeating units of a group of alkali metal salts or ammonium imino disulfonyl. The latex composition contains 0 to 3% surfactant based on the total weight of the polyester. Due to the hydrophobe and latex composition, it exhibits the water repellent properties.

US 2600457 A relates to fast air drying and baking drying fusible copolymers of fatty oil modified polyesters and vinyl monomers. A) The vinyl monomer having the formula of CH2=CHR. Here R belongs to the unsaturated group comprising of aryl, heterocyclic, carboxy, ketonic, nitrile, and amido. B) The fatty oil modified polyesters comprised of polyhydric alcohol and glycerides in fatty oils chosen from group comprising of saturated acids and unsaturated non-conjugated acids with a dibasic adduct chosen from the group comprising of delta-1,4- dihydrophthalic acid and the Diels-Alder adducts of a diolefine chosen from the group comprising of, dicyclopentadiene and cyclopentadiene and an acidic reactant chosen from the group comprising of the acids and maleic anhydride, chloromaleic anhydride and fumaric anhydride. This copolymers act as adhesives, binders, molding material and other coating applications.
OBJECTS OF THE INVENTION
The object of the current invention is to synthesize oil modified aclin resin containing formulation, possessing excellent impermeability to corrosive ions and hydrophobic properties.
Another object of the current invention is to provide an impervious layer to galvanized steel sheets in corrosive media, evaluated by polarization studies.
A further object of this invention is to provide coating with water-repellent properties, measured by contact angle measurement techniques.

DETAILED DESCRIPTION OF THE INVENTION
The present invention describes coating formulations based upon- oil modified natural aclin resin (various waterborne and solvent borne formulations) having excellent im-permeability of corrosive ions and hydrophobic properties on metallic surfaces especially on no-spangled galvanized iron.
According to this invention, the aclin resin with formula C20H17FO3S is modified by linseed oil or tung oil in the ration of 1:9 (resin to oil). Linseed oil is having at least one formula C57H98O6 and tung oil is having at least one formula C18H30O2.
This invention provides two kinds of systems a) water borne b) solvent -borne system and both provide linseed/tung oil modified aclin resin which is synthesized by mixing of linseed oil/tung oil into aclin resin in the ratio of 1:9 (resin to oil) in a reaction vessel for 5 hours at 80°C while passing the nitrogen gas. This resin helps in film formation and resistance to corrosion and oil improves its water repellent properties.
Preparing Water Borne Formulations: Water borne system: The measured quantity of prepared oil modified resin in weight proportion of 7-12 wt. % is taken into a beaker and mixed with 1 to 2 wt. % of borax, 3- 7 wt. % of carboxy methyl cellulose/hydroxypropyl methyl cellulose and 34-38 wt. % of water. The mixture is stirred till it dissolves completely. If required, 3 to 4 wt. % of ammonia solution can be added to increase dissolvability. Water is required for reducing the viscosity. The prepared solution is mixed with 1-2 wt. % of flexibilizer-ethylene glycol/propylene

glycol along with 40-45 wt. % of a polar solvent. Polar solvent such as iso-propyl alcohol/butyl alcohol can be used for preparing the solution. The as-obtained solution is mixed with 1 -2 wt. % of an adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane and 1-2 wt. % of levelling agent and wetting agent such as acrylic silicon copolymer. For enhancing, the corrosion resistance and adhesion, 2 to 5 wt. % of 3-(trimethoxysilylpropyl) methacrylate or vinyl-2-amino-2-phenyl carboxylate salt is added.

Solvent borne Formulations: 7-12 wt. % of oil modified resin is taken into a beaker and then mixed with about 1 -2 wt. % of flexibilizer-propylene

glycol/ethylene glycol and 2 to 5 wt. % of corrosion inhibitor i.e. 3-(triethoxysilylbutyl) methacrylate / acryl-2-amino-2-phenyl carboxylate salt. 3-(triethoxysilylbutyl) methacrylate is used as an adhesion promoter as well. This mixture is continuously stirred with 80 -90 wt. % of iso-propyl alcohol/butyl alcohol for up to half an hour. The as-obtained solution is mixed with 1 -2 wt. % of adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane.


The oil modified natural aclin resin based coatings can be applied by known methods such as wiping, brushing, spraying and dipping, preferably spraying. The curing is done for 10-300 seconds at a temperature of 27°C and forms a dense structure of coating (DFT: l-lO^m) for water repellence and polarization test, salt spray test (ASTM Bl 17) as described in Table 5, Figure 1, 2 and 3.


Example 1 (WLV) : In the current embodiment, the formulation is developed with 8 wt. % of linseed oil modified aclin resin. The linseed modified resin is synthesized by mixing of linseed oil into aclin resin in the ratio of 1:9 in a reaction vessel for 5 hours at 80°C while passing the nitrogen gas. To the oil modified resin is added 2 wt. % borax, 3 wt. % of carboxy methyl cellulose and 38 wt. % of water into above reaction mixture and stirring till it dissolves completely. Water is required for reducing the viscosity. Now prepared solution is mixed with 1 wt. % of flexibilizer propylene glycol with 44 wt. % of polar solvent such as iso-propyl alcohol. The as-obtained solution is mixed with 0.5 wt. % of adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane with levelling and wetting agent such as 1 wt. % of acrylic silicon copolymer. For enhancing the corrosion resistance of the solution, 2.5 wt. % of vinyl-2-amino-2-phenyl carboxylate salt is added. This brownish black coating solution is having 0.85 specific gravity and 24 mili pascal viscosity. The coating is applied by spraying method to develop a coating of 2 μm thickness which cures within 150 seconds at 27°C.
Example 2 ( WLMP): In the current example, the formulation comprises 8 wt. % of linseed oil modified aclin resin. The linseed oil modified aclin resin is synthesized by mixing of linseed oil into aclin resin in the ratio of 1:9 in a reaction vessel for 5 hours at 80°C while passing the nitrogen gas. This oil modified resin helps in film formation and imparting corrosion resistance. Mixed oil improves its water repellent properties. 2 wt. % borax, 3 wt. % of hydroxypropyl carboxy methyl cellulose and 38 wt. % of water are added to the oil modified resin, and stirred till it dissolves completely. Water is required for reducing the viscosity. Now prepared solution is mixed with 1 wt. % of flexibilizer ethylene glycol in 44 wt. % of polar solvent of butyl alcohol. The as-obtained solution is mixed with 0.5 wt. % of

adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane with levelling and wetting agent such as 1 wt. % of acrylic silicon copolymer 2.5 wt. % of 3-(trimethoxysilylpropyl) methacrylate is added further to increase corrosion resistance. The resultant solution is applied by spraying method to develop a coating of 1 μm thickness which cures within 70 seconds at 27°C.
Example 3 (WTV): The current formulation comprises 8 wt. % of tung oil modified aclin resin. The oil modified aclin resin is synthesized by mixing of tung oil into aclin resin in the ratio of 1:9 in a reaction vessel for 5 hours at 80°C while passing the nitrogen gas. 2 wt. % of borax, 4 wt. % of ammonia, 7 wt. % of carboxy methyl cellulose and 34 wt. % of water is added to the oil modified aclin resin and stirred till it dissolves completely. Water is required for reducing the viscosity. Now prepared solution is mixed with 1 wt. % of flexibilizer propylene glycol with 44 wt. % of polar solvent of iso-propyl alcohol. The as-obtained solution is mixed with 0.5 wt. % of adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane with 1 wt. % of levelling agent such as acrylic silicon copolymer. 2.5 wt. % of vinyl-2-amino-2-phenyl carboxylate salt is added to enhance the corrosion resistance of the solution. The resultant coating solution is having 0.76 specific gravity and 28 mill pascal viscosity. The said coating solution is applied by spraying method to develop 2 jim thick on a metallic substrate which cures within 45 seconds at 27°C.
Example 4 (WTMP): The current formulation comprises 8 wt. % of tung oil modified aclin resin. The oil modified aclin resin is synthesized by mixing of tung oil into aclin resin in the ratio of 1:9 in a reaction vessel for 5 hours at 80°C while passing the nitrogen gas. 2 wt. % borax, 3 wt. % of hydroxypropyl carboxy methyl

cellulose and 38 wt. % of water are added into oil modified aclin resin and stirred till it dissolves completely. Water is required for reducing the viscosity. The prepared solution is mixed with 1 wt. % of flexibilizer ethylene glycol with 44 wt. % of polar solvent of butyl alcohol. The as-obtained solution is mixed with 0.5 wt. % of adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane with 1 wt. % of levelling and wetting agent such as acrylic silicon copolymer. 2.5 wt. % of 3-(trimethoxysilylpropyl) methacrylate is added further to enhance corrosion resistance properties. The resultant pale yellow coating solution having 0.87 specific gravity and 18 mili pascal viscosity is applied by spraying method to develop a coating of 20 μm thickness which cures within 300 seconds at 27°C.
Example 5 (SLA): The current formulation comprises 10 wt. % linseed oil modified resin. The oil modified resin is taken into a beaker and about 1 wt. % of flexibilizer-propylene glycol with 2.5 wt. % of corrosion inhibitor i.e. acryl-2-amino-2-phenyl carboxylate salt is added. This mixture is continuously stirred with 86 wt. % of iso-propyl alcohol up to half an hour. The as-obtained solution is mixed with about 0.5 wt. % of an adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane This brownish black coating solution having 0.76 specific gravity and 7 mili pascal viscosity is applied by spraying method to develop a coating of 1 fim thickness which cures within 73 seconds at 27°C.
Example 6 (SLEB): The prepared linseed oil modified resin (10 wt. %) is taken in a beaker and then is mixed with 1 wt. % flexibilizer-ethylene glycol and 2.5 wt. % of corrosion inhibitor i.e. 3-(triethoxysilylbutyl) methacrylate. This mixture is

continuously stirred with 86 wt. % of butyl alcohol up to half an hour. The as-obtained solution is mixed with adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane about 0.5 wt. %. This brownish black coating solution having 0.72 specific gravity and 7 mili pascal viscosity is applied by spraying method to develop 1 μrm thick coating which gets cured within 19 seconds at 27°C.
Example 7 (STA): The prepared tung oil modified resin (10 wt. %) is taken in a beaker and then is mixed with 1 wt. % flexibilizer-propylene glycol and 2.5 wt. % of corrosion inhibitor i.e. acryl-2-amino-2-phenyl carboxylate salt. This mixture is continuously stirred with 86 wt. % of iso-propyl alcohol up to half an hour. The as-obtained solution is mixed with adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane about 0.5 wt. %. This pale yellow coating solution having 0.71 specific gravity and 8 mili pascal viscosity is applied by spraying method to develop 1 jim thick coating which cures within 94 seconds at 27°C.
Example 8 (STEB): The prepared tung oil modified resin (10 wt. %) is taken in a beaker and then mixed with fiexibilizer-ethylene glycol about 1 wt. % with 2.5 wt. % of corrosion inhibitor i.e. 3-(triethoxysilylbutyl) methacrylate. This mixture is continuously stirred with 86 wt. % of butyl alcohol up to half an hour. The as-obtained solution is mixed with 0.5 wt. %. Of adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane. This pale yellow coating solution having 0.73 specific gravity and 8 mili pascal viscosity is applied by spraying method to develop 10 μm thick coating which cures within 10 seconds at 27°C.

Hereto, all invention is useful for structural applications, plumbing application and automobile industry to mitigate the galvanic coupling problem such as in bolts and threaded parts where the galvanized iron becomes prone to the environmental corrosion due to the zinc coating removal. As a result of this, substrate exhibits the galvanic coupling between removed part of zinc.
The formulations of all examples axe described in Table 2 and 3. All inventions exhibit excellent fluid and film properties (Table 4 and Table 5). Among all the examples, STEB is showing good properties in terms of anticorrosion (Figure 1 and 2) and water repellent (Figure 3) properties, as to evident by salt spray test, polarization study and contact angle measurement respectively.
The lower corrosion current density, higher sustainability towards rusting in salt spray chamber and higher water contact angle (hydrophobicity) depict the lower corrosion rate of STEB and WTV.

Figure la exhibits the result of corrosion resistance properties for described
waterborne systems (WLV, WLMP, WTV and WTMP).
Corrosion rate of waterborne systems: WTV < WTMP < WLMP < WLV.
Figure lb exhibits the result of corrosion resistance properties for described solvent
borne systems (STEB, SLEB, SLA and STA).
Corrosion rate of solvent borne systems: STEB < SLEB < SLA < STA.
Corrosion rate and current density: STEB < WTV < SLEB < WTMP < SLA < WLMP < WLV < STA. In the similar way, Figure 2 exhibits the results of sustainability towards rusting using salt spray test. More sustainability of coated samples under the exposure of salt spray fog indicates the more corrosion resistant properties.
Figure 3 exhibits the water repellent properties of waterborne and solvent borne coated samples. Comparatively, all examples show >90° contact angle which means hydrophobic nature or water repellence properties. As the contact angle increases, hydrophobicity or water repellence property increases. So, the lower corrosion current density, higher sustainability towards rusting in salt spray chamber and higher water contact angle (hydrophobicity) depict the lower corrosion rate of STEB and WTV. Among various formulations, STEB demonstrates best performance in terms of adhesion, water repellent properties (112°), salt spray test (216 hours), lower corrosion current density (5.21 E-08) and lower corrosion rate (0.000606 mm/year).

WE CLAIM:
1. An anticorrosion and water repellent coating formulation for coating on
galvanized steel, the formulation comprising:
oil modified natural aclin resin wherein aclin resin is modified by linseed oil or tung oil in the ratio 1:9 (resin to oil).
2. The anticorrosion and water repellent formulation as per the claim 1, wherein the formulation is water borne or solvent borne coating formulation.
3. The anticorrosion and water repellent formulation as per the claim 1 or claim 2, wherein the water borne coating formulation further comprises in weight%;
40 to 45 wt. % of Isopropyl alcohol or Butyl alcohol;
3 -7 % Carboxy methyl cellulose or hydroxypropyl methyl cellulose;
2 to 5 wt. % of 3-(trimethoxysilylpropyl) methacrylate or vinyl-2-amino-2-phenyl carboxylate salt; 1-2 wt. % of a flexibilizer ethylene glycol or propylene glycol;
34 to 38 % Water, 0.5 % GPTMS,
1-2 wt. % of levelling agent and wetting agent acrylic silicon copolymer; and
2% Borax.
4. The anticorrosion and water repellent formulation as per the claim 3, wherein 3 to 4 wt. % of ammonia solution is added to increase dissolvabiliry.
5. The anticorrosion and water repellent formulation as per the claim 1 or claim 3, wherein said vinyl-2-amino-2-phenl carboxylate salt is having at least one formula CioH11O2N, its chemical structure is:


7. The anticorrosion and water repellent formulation as per the claim 1 or claim 2,
wherein solvent borne coating formulation further comprises in weight%;
1 -2 wt. % of flexibilizer-propylene glycol or ethylene glycol;
2 to 5 wt. % of corrosion inhibitor - 3-(triethoxysilylbutyl) methacrylate or
acryl-2-amino-2-phenyl carboxylate salt;
an adhesion promoter, 3-(triethoxysilylbutyl) methacrylate;
80 -90 wt. % of iso-propyl alcohol or butyl alcohol; and
1 -2 wt. % of adhesion promoter-3-(glycidyloxypropyl) tri-methoxy silane.
8. The anticorrosion and water repellent formulation as per the claim 7, wherein
said acryl-2-amino-2-phenl carboxylate salt is having formula C11H14O2N, and its
chemical structure is:


lO.The anticorrosion and water repellent formulation as per any of the preceding the claims, wherein the formulation provides contact angle of at least 90 degree.
11. The anticorrosion and water repellent formulation as per any of the preceding the claims, wherein the formulation withstand salt spray test in the range of 96 hours to 216 hours.
12.The anticorrosion and water repellent formulation as per any of the preceding the claims, wherein the formulation provides corrosion rate in the range of 0.000606 to 0.1221 mm/year.