DESC:Field of Invention:

The present invention relates to preparation of a water soluble epoxy resin by reacting bisphenol A based epoxy resin containing at least two epoxy groups, or cycloaliphatic epoxy resin containing at least two epoxy groups with aliphatic or aromatic amines, followed by reaction with novolac resins and/or epoxy diluents. Finally, acrylation is done with these epoxy amine adducts to obtain a water dispersible polymer. Neutralizing the free carboxylic acid groups present in the synthesized resin with amine, water dispersible resin is obtained providing a milky white dispersion in water.

Background of the invention.

At present, corrosion is a major concern for metal parts used in different equipment in industries, vehicles, and households. The lifetime of the metal parts reduces significantly when exposed to environmental hazards. To overcome this issue, it is required to use a suitable coating on the metal so that the harmful effect of hazards is reduced significantly. Epoxy resins are good at preventing corrosion on metal surfaces. Therefore, use of epoxy resin on this purpose could be a good solution. Now the resin could be both solvent borne and water borne. Solvent borne epoxy resin gives good result on this aspect but it is not good for health. On the other hand, water borne system is environment friendly system. Therefore, water borne system could be a good solution for greener environment.
References are invited for few relevant prior arts to the present invention:

US patent, 13/695,695, publication No. US 2013/0090413 A1; Pub. Date: Apr.11, 2013, filed on September 21, 2011 discloses synthesis of a water-soluble epoxy resin by reacting an epoxy resin having two or more epoxy groups in a molecule with a carboxy-group containing compound obtained by reacting a polyethylene glycol monoalkyl ether and an acid anhydride derived from a polyvalent carboxylic acid; a water soluble epoxy resin composition; and a water-based epoxy resin composition.

US patent, Application No. 526,997, Pub. Date: Oct. 12, 1976, filed on Nov. 25, 1974. depicts a waterborne epoxy resin prepared by reacting a bisphenol A type epoxy resin, and a monofunctional epoxy, for example phenyl glycidyl ether, with a dibasic acid followed by reaction with trimellitic anhydride and subsequent neutralization of carboxyl acid groups. This resin is dispersed in an aqueous medium, applied to a metal substrate and cured by heating.
US20150119499A1/US9701864B2 relates to compounds comprising the epoxide functional reaction product of: (a) at least one molecule comprising two terminal epoxy-reactive moieties; with (b) two molecules comprising two epoxide moieties; wherein, said compound comprises, pendent to the residue of (a) (i.e. as a side chain of the molecule), one or more polyoxyalkylene or
polyoxyalkylene alkyl ether radical(s) having a weight average molecular weight of at least 400. Also provided aqueous coating compositions comprising such compounds.
CN111662531 discloses a water-soluble epoxy resin dispersion and a preparation method thereof, wherein the water-soluble epoxy resin dispersion comprises the following components: a first modified epoxy resin comprising a first epoxy resin derived unit and an anhydride resin derived unit; and a second modified epoxy resin including a second epoxy resin derived unit and a polyol derived unit wherein the epoxy equivalent of the first epoxy resin is 100 to 700 g/eq. The water-soluble epoxy resin dispersion is water-soluble, environmentally friendly, and effective in rust resistance, adhesion, and water resistance.
WO2012043320 (JPWO2012043320A1) provides a water-soluble epoxy resin that can obtain a cured product that is excellent in coating film strength and corrosion resistance while maintaining emulsion stability to the epoxy resin, and has water resistance and alkali resistance. The composition of the advancement comprises a carboxy group-containing compound (A) obtained by reacting a polyethylene glycol monoalkyl ether (A-1) having a number average molecular weight of 400 to 10,000 with an acid anhydride (A-2) derived from a polycarboxylic acid. And an epoxy resin (B) having two or more epoxy groups in the molecule, a water-soluble epoxy resin obtained by reacting the epoxy resin (B) having two or more epoxy groups in the molecule. A water-soluble epoxy resin composition containing a resin and an aqueous epoxy resin composition in which the water-soluble epoxy resin composition is dispersed in an aqueous solvent are provided.
CN114249900A discloses a preparation method of an epoxy emulsifier, an epoxy resin aqueous dispersion and a preparation method thereof, wherein the preparation method of the epoxy emulsifier comprises the following steps: reacting polyether with anhydride to obtain a polyether-anhydride product, and then reacting the obtained polyether-anhydride product with epoxy resin to obtain a polyether-anhydride-epoxy product; reacting the polyether-anhydride- epoxy product with phosphoric acid or phosphate to obtain an epoxy emulsifier; the epoxy resin aqueous dispersion prepared by the emulsifier show the characteristics of good stability and excellent corrosion resistance after curing, and can be used in the fields of coatings, adhesives and the like.

Japanese patent No. 4890688 discloses a water-soluble epoxy resin dispersion liquid comprising a polyalkylene glycol-modified epoxy resin obtained by reacting a polyalkylene glycol, a bisphenol epoxy resin, an active hydrogen- containing compound and an isocyanate compound; an epoxy-containing resin; and a modified epoxy resin obtained by reacting a hydrazine derivative. However, the water-soluble epoxy resin dispersion liquid of patent document has a problem that the viscosity after water dispersion is high and the appearance and rust resistance of the resulting coating film are insufficient.
US6294596B1 discloses a self-dispersing curable epoxy composition prepared upon contacting an epoxy resin with a polyoxyalkyleneamine having a molecular weight of from about 3,000 to about 15,000 in a ratio of about 0.001 to 0.060 reactive equivalents of polyoxyalkyleneamine to about 1.0 reactive equivalents of epoxy resin. The self-dispersing curable epoxy resin forms an aqueous dispersion upon mixing with water. When cured, the dispersion is useful as a coating composition.

WIPO patent, Application No. PCT/CN2019/104363, publication No. WO 2021/042285 A1; Pub. Date: Mar. 11, 2021, filed on September 4, 2019, prepared a self-emulsified epoxy resin composition by components comprising epoxy adduct, and an epoxide compound. This self-emulsified resin was used to prepare coating formulation for the anticorrosion application and the coating has good performance.

Although various anticorrosion formulations involving epoxy resin are available for metals like mild steel, copper, aluminum, galvanized iron in the market or reported- still there is enough scope for development of anticorrosive resin with better features, longer stability and at the same time more cost effective.

Objectives of the Invention

The primary objective of the present invention is to prepare a water dispersible epoxy resin which would show excellent anticorrosion properties on metals like mild steel, copper, aluminum, galvanized iron.
Another preferred objective of the present invention is to prepare said water dispersible epoxy resin by reacting bisphenol A type epoxy resin having at least two epoxy groups, or cycloaliphatic epoxy resin or modified cycloaliphatic epoxy resins having at least two epoxy groups with aliphatic or aromatic amines, followed by reaction with Novolac resins and/or epoxy diluents and finally acrylation with suitable monomers.
Another objective of the present invention is to prepare said water dispersible epoxy resin which would be quick drying, flexible, and would have very good adhesion on metal surface to achieve the anticorrosion properties.
Another objective of the present invention is to prepare said water dispersible epoxy resin which could be formulated either as solvent borne coating system or environment friendly water borne coating system.
Another objective of the present invention is to prepare said water dispersible epoxy resin which would be one component epoxy system having stability at room temperature as well as at elevated temperature (55oC for 2 months).
Another objective of the present invention is to prepare said water dispersible epoxy resin which would be cost effective and method of preparation would be simple and easy to scale up.

Another objective of the present invention is to prepare said water dispersible epoxy resin which can be operational at hot condition also and after curing would provide a hard coating system having excellent anticorrosive property.

Summary of the Invention

In the primary aspect the present invention is directed to provide an anticorrosion water based epoxy resin comprising of
a water dispersible acrylated epoxy amine salt resin providing for a coating with average dry film thickness of 15-20 µm after curing which comprises of an acrylated and neutralized anticorrosion coating composition of an epoxy amine adduct of
a. bisphenol A based epoxy resin containing at least two epoxy groups, or cycloaliphatic epoxy resin containing at least two epoxy groups;
b. aliphatic or aromatic amines;
c. epoxy resin containing at least two aromatic rings;
d. epoxy resin containing at least one aromatic ring and one epoxy group as reactive epoxy diluents.

Another aspect of the present invention is directed to provide said anticorrosion water based epoxy resin wherein said epoxy amine adduct comprises
a. bisphenol A based epoxy resin containing at least two epoxy groups, or cycloaliphatic epoxy resin containing at least two epoxy groups (10- 50%)
b. aliphatic or aromatic amines (1 – 10%)
c. epoxy resin containing at least two aromatic rings preferably the phenol Novolac resin (1-20%)
d. epoxy resin (0.1-20 %) containing at least one aromatic ring and one epoxy group as reactive epoxy diluents;
which upon acrylation with suitable monomers (5-40%) followed by neutralization of free acids with amine provides said water dispersible acrylated epoxy amine salt.

Another aspect of the present invention is directed to provide said anticorrosion water based epoxy resin which is quick drying, flexible and having selectively excellent adhesion on mild steel, copper, galvanized iron and aluminium surface wherein
said bisphenol A based epoxy resin containing at least two epoxy groups having epoxy equivalent weight range in between 180 – 3000 g/eq. and is selected from YD-124, YD-125, YD-126, YD-127, YD-128, YD011x75, YD012x75, YD134x80, YD-901x75, YDF170, YDF-171, YDF172, YDF-173, YDFM-251, YDFM-270, YDFM-253, YDFM-261, YDFM-269, YDFM-262, YDFM- 250, YDFM-256, YD-901, YD-902, YD-903, YD-904, YD-905, YD-907, YD-909, YD-012, YD-013, YD-014, YD-942, YD-972, YD-017, YD-019, YD-010S; and

said cycloaliphatic epoxy resins have epoxy equivalent weight in the range of 180 – 720 g/equivalent includes ARCH-11, ARCH-12, ARCH-13, ARCH-13LV, ARCH-18.

Yet another aspect of the present invention is directed to provide said anticorrosion water based epoxy resin wherein said aliphatic and aromatic amine is/are selected from aniline, N- methyl aniline, triethylene tetramine, diethylene triamine, 2-butanamine, 3- methyl-1-butanamine, n-butylamine, n-octylamine, 2-aminoethanol, aminoethanoic acid, ethylene diamine, diethanolamine, 4-aminobenzoic acid, hexane-1,6-diamine, benzene-1,4-diamine, ethylamine, cyclohexyl amine, 2-methylbutylamine, 2-(cyclo octylethyl)amine, 3-(cyclopropylpentyl)amine, 3- (metylpentyl)amine, 2-(cycloheptylethyl)amine, tris-2-aminoethylamine, bis(3- aminopropyl)amine.

Further aspect of the present invention is directed to provide said anticorrosion water based epoxy resin wherein said Phenol Novolac resin is selected from ARPN-25, ARPN-36, ARPN-36 M80, ARPN-53, ARPN-54, YDPN – 638LV, YDPN-661, YDPN-638X80; and
said acrylic monomers include 2-hydroxylethylmethacrylate, methyl- methacrylate, acrylamide, N,N-dimethyl acrylamide, acrylic acid, styrene, glycidyl methacrylate, methacrylic acid, 2-(dimethylamino)ethyl methacrylate, 2-ethyl hexylacrylate, UL-513, butyl acrylate, butylmethacrylate, 1-vinyl-2-pyrrolidone, acrylonitrile, and vinyl acetate; and
said epoxy reactive diluents include RD-108, RD-109, RD-110, RD-118, RD-103, RD-111, RD-114, RD- 119, RD-121, RD-133, RD-113, RD-124, RD-129, RD-131, RD-104, RD-105, RD-106, RD-136, RD-138, RD-137, UL-513; and using ethylene glycol monobutyl ether as the solvent.

Another preferred aspect of the present invention is directed to provide a method for the synthesis of anticorrosion water based epoxy resin comprises the steps of
a. providing bisphenol A based epoxy resin containing at least two epoxy groups, or cycloaliphatic epoxy resin containing at least two epoxy groups mixed in a solvent;
b. adding aliphatic or aromatic amines and reacted at elevated temperature;
c. adding epoxy resin containing at least two aromatic rings preferably, the phenol novolac resin;
d. adding another epoxy resin containing at least one aromatic ring and one epoxy group as reactive epoxy diluents;
heating at 80-100 oC for three more hours to make an epoxy amine adduct for obtaining therefrom said water dispersible acrylated epoxy amine salt resin providing for a coating with average dry film thickness of 15-20 µm after curing.

Another aspect of the present invention is directed to provide said method for synthesis wherein said synthesis of said epoxy amine adduct comprises the steps of
a. providing bisphenol A based epoxy resin containing at least two epoxy groups having epoxy equivalent weight range in between 180 – 3000 g/eq. (10- 50%), and/or cycloaliphatic epoxy resin containing at least two epoxy groups have epoxy equivalent weight in the range of 180 – 720 g/equivalent (10- 50%) mixed in ethylene glycol monobutyl ether as the solvent by heating at 80-100 oC;
b. adding aliphatic or aromatic amines (1 – 10%) and reacted at 80-100 oC for three hours;
c. adding epoxy resin containing at least two aromatic rings preferably, the phenol novolac resin (1-20%) and heating at 80-100 oC for three hours;
d. adding another epoxy resin (0.1-20 %) containing at least one aromatic ring and one epoxy group as reactive epoxy diluents in the reaction mixture and heating at 80-100 oC for three hours to provide said epoxy amine adduct.

Still further aspect of the present invention is directed to provide said method for synthesis comprises
a. carrying out acrylation of as obtained epoxy amine adduct by reaction with suitable monomers (5-40 %) in the temperature range 60– 130 oC for three more hours;
wherein suitable monomer/s is/are selected from the list of monomers e.g. 2- hydroxylethyl methacrylate, methyl methacrylate, acrylamide, N,N-dimethyl acrylamide, acrylic acid, styrene, glycidyl methacrylate, methacrylic acid, 2- (dimethylamino)ethyl methacrylate, 2-ethyl hexylacrylate, UL-513, butyl acrylate, butyl methacrylate, 1-vinyl-2-pyrrolidone, acrylonitrile, and vinyl acetate;
followed by neutralizing the free acids of acrylated epoxy amine adduct with suitable amine provides the desired water dispersible acrylated epoxy amine salt resin.

Description of the invention:

The present invention of synthesizing water based epoxy resin for anticorrosion application involves modification of bisphenol A based epoxy resin containing at least two epoxy groups, or cycloaliphatic epoxy resin containing at least two epoxy groups with aromatic or aliphatic amines, followed by further modification with another epoxy resin containing at least two aromatic rings, and/or another epoxy resin containing at least one aromatic ring. Obtained intermediate is subjected to acrylation and finally, the as synthesized resin is dispersed into water by neutralizing the free acids with amine.
In one embodiment of the present invention the bisphenol epoxy resins used have epoxy equivalent weight range in between 180 – 3000 g/eq. Optionally the resins are modified to impart desired characteristics.
In another embodiment aromatic epoxy resin used for the present invention is selected from YD-124, YD-125, YD-126, YD-127, YD-128, YD011x75, YD012x75, YD134x80, YD-901x75, YDF170, YDF-171, YDF172, YDF-173, YDFM-251, YDFM-270, YDFM-253, YDFM-261, YDFM-269, YDFM-262, YDFM- 250, YDFM-256, YD-901, YD-902, YD-903, YD-904, YD-905, YD-907, YD-909, YD-012, YD-013, YD-014, YD-942, YD-972, YD-017, YD-019, YD-010S- (All are procured from Epotec India).

In another embodiment of the present invention said cycloaliphatic epoxy resins have epoxy equivalent weight in the range of 180 – 720 g/equivalent. Said cycloaliphatic epoxy resins were modified if required. Cycloaliphatic epoxy resin includes ARCH-11, ARCH-12, ARCH-13, ARCH-13LV, ARCH-18 (All are procured from Atul India).
In another embodiment epoxy reactive diluents used for the present invention includes RD-108, RD-109, RD-110, RD-118, RD-103, RD-111, RD-114, RD- 119, RD-121, RD-133, RD-113, RD-124, RD-129, RD-131, RD-104, RD-105, RD-106, RD-136, RD-138, RD-137, UL-513. (These reactive diluents are procured from Epotec India and cardolite). The reactive diluents are used in between 0.1 – 10%.
In one embodiment the epoxy phenol novolac resin used for the present invention is/are selected from ARPN-25, ARPN-36, ARPN-36 M 80, ARPN-53, ARPN-54, YDPN – 638LV, YDPN-661, YDPN-638X80. (Procured from either Epotec or Atul, India).
In another embodiment the amines used in this invention includes aniline, N- methyl aniline, triethylene tetramine, diethylene triamine, 2-butanamine, 3- methyl-1-butanamine, n-butylamine, n-octylamine, 2-aminoethanol, aminoethanoic acid, ethylene diamine, diethanolamine, 4-aminobenzoic acid, hexane-1,6-diamine, benzene-1,4-diamine, ethylamine, cyclohexyl amine, 2-methylbutylamine, (2-cyclooctylethyl)amine, (3-cyclopropylpentyl)amine, (3- metylpentyl)amine, (2-cycloheptylethyl)amine, tris-2-aminoethylamine, bis(3- aminopropyl)amine.
In further embodiment the solvent used for the synthesis of water based epoxy resin for anticorrosion application is ethylene glycol monobutyl ether and the acrylic monomers used in the synthesis include 2-hydroxylethyl methacrylate, methyl methacrylate, acrylamide, N,N-dimethyl acrylamide, acrylic acid, styrene, glycidyl methacrylate, methacrylic acid, 2-(dimethylamino)ethyl methacrylate, 2-ethyl hexylacrylate, UL-513, butyl acrylate, butylmethacrylate, 1-vinyl-2-pyrrolidone, acrylonitrile, and vinyl acetate.
The average dry film thickness of the coating after curing is 15-20 µm for all the testing. Upon salt spray testing (SST) the coating in accordance to the present invention showed no corrosion up to 240 hours.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. The advancement according to the present invention is discussed in further detail in relation to the following non-limiting exemplary illustrations wherein:

Figure 1: SST image of the as such resin from Example 1 on mild steel at different time intervals after drying at 150 oC for 30 min on mild steel. The average dry film thickness (DFT) of the coating was in between 15 – 20 µ. The resin was spray coated after dilution to suitable viscosity. Cross cut on the coating was done to observe the corrosion around it with time.
Figure 2: SST image of as such resin (Example-2) on mild steel at different time intervals after drying at 150 oC for 30 min on mild steel. The average dry film thickness (DFT) of the coating was in between 15 – 20 µ. The resin was spray coated after dilution to suitable viscosity. Cross cut on the coating was done to observe the corrosion around it with time.
Figure 3: Size distribution of resin in 0.05% solution prepared by present invention (Example 1). The resin first dried in oven at 150 oC for 1 hour and then dissolved in suitable solvent. The particle size distribution of the resin then analyzed by Anton Paar Lite Sizer 500 instrument. The particle size is taken as the average of three data.
Figure 4: FTIR data of the dried sample (Example 1) was recorded in the 4000 - 450 cm-1 range by making pellet with KBr.
Figure 5: SST images of the as such resin (Example 1) at different time intervals after drying at 150 oC for 30 min on galvanized iron, copper, and aluminium. The average dry film thickness (DFT) of the coating was in between 15 – 20 µ. The resin was spray coated after dilution to suitable viscosity. Cross cut on the coating was done to observe the corrosion around it with time.

Examples

Example 1.

In a four necked round bottom flask, the desired aromatic epoxy resin (10- 50%) and/or cycloaliphatic epoxy resin (10-50%) were mixed in a solvent or solvent mixture and dissolved it by heating at 80-100 oC. Then the amine (1 – 10%) was added to the reaction mixture at the same temperature and reacted for three hours. Next, the phenol novolac resin (1-20%) was added to the reaction mixture and reacted for three hours at 80-100 oC. Finally, another epoxy resin (0.1-20 %) containing at least one aromatic ring and one epoxy group selected from RD-108, RD-109, RD-110, RD-118, RD-103, RD-111, RD-114, RD- 119, RD-121, RD-133, RD-113, RD-124, RD-129, RD-131, RD-104, RD-105, RD-106, RD-136, RD-138, RD-137, UL-513 as reactive epoxy diluents were reacted with it at 80-100 oC for three more hours to make an epoxy amine adduct. Acrylation was done with this epoxy amine adduct in the temperature range 60– 130 oC using suitable monomers (5-40 %) from the list of monomers e.g. 2- hydroxylethyl methacrylate, methyl methacrylate, acrylamide, N,N-dimethyl acrylamide, acrylic acid, styrene, glycidyl methacrylate, methacrylic acid, 2- (dimethylamino)ethyl methacrylate, 2-ethyl hexylacrylate, UL-513, butyl acrylate, butyl methacrylate, 1-vinyl-2-pyrrolidone, acrylonitrile and vinyl acetate. Finally, the synthesized resin was dispersed in water after neutralizing with suitable amine.

Method of synthesis
The synthesis of water dispersible acrylated epoxy amine salt comprises the steps of
a. providing bisphenol A based epoxy resin containing at least two epoxy groups having epoxy equivalent weight 180 – 3000 g/eq. (10- 50%), and/or cycloaliphatic epoxy resin containing at least two epoxy groups having epoxy equivalent weight in the range of 180 – 720 g/equivalent (10- 50%) in a 4 necked container having ethylene glycol monobutyl ether as the solvent are mixed by heating at 80-100 oC;
b. adding aliphatic or aromatic amines (1 – 10%) and reacted at 80-100 oC for three hours;
c. adding epoxy resin containing at least two aromatic rings preferably, the phenol novolac resin (1-20%) with continued heating at 80-100 oC for three hours;
d. adding another epoxy resin having one aromatic ring and one epoxy group (0.1-20 %) as reactive epoxy diluents to the reaction mixture and heated at 80-100 oC for three hours to provide epoxy amine adduct;
e. carrying out acrylation of as obtained epoxy amine adduct by reaction with monomers (5-40 %) in the temperature range 60– 130 oC for three more hours;

followed by neutralizing the as synthesized acrylated epoxy amine adduct with suitable amine provides the desired water dispersible acrylated epoxy amine salt resin.

Example 2
In a four necked round bottom flask, the desired aromatic epoxy resin (10-50%) and/or cycloaliphatic epoxy resin (10-50%) were mixed in a solvent or solvent mixture and dissolved it by heating at 80-100 oC. Then the amine (1 – 10%) was added to the reaction mixture at the same temperature and reacted for three hours.
Next, acrylation was done with suitable monomers (5-40 %) in the temperature range 60- 130oC selected from given list e.g. 2-hydroxylethyl methacrylate, methyl methacrylate, acrylamide, N,N-dimethyl acrylamide, acrylic acid, styrene, glycidyl methacrylate, methacrylic acid, 2-(dimethylamino)ethyl methacrylate, 2-ethylhexylacrylate, UL-513,butylacrylate, butylmethacrylate, 1-vinyl-2-pyrrolidone, acrylonitrile, vinyl acetate for three more hours. Finally, the synthesized resin was dispersed in water after neutralizing with suitable amine.
The water dispersible acrylated epoxy amine salt resin prepared in example 2
is devoid of epoxy resin containing at least two aromatic rings preferably, the phenol novolac resin (1-20%) along with another epoxy resin (0.1-20 %) used as reactive epoxy diluents for the Example-1 resin.

Example-3

Testing
The curing of this coating before salt spray test (SST) and water dip test is done at 150 oC for 30 min. For cross cut adhesion and flexibility test, the coating is done on mild steel, galvanized iron, copper, and aluminium panel followed by curing. The average dry film thickness of the coating is 15-20 µ for all the testing. The film of the polymer coated substrates is obtained by spraying the polymer dispersion after proper dilution with water using a spray gun. The salt spray test (or salt fog test) is a standardized and popular corrosion test method (ASTM B117), used to check corrosion resistance of materials and surface coatings.
The SST result of Example 1 and as such resin (Example-2) are shown in the Figure 1, Figure 2, and figure 5 respectively. SST results show that there is no corrosion happened up to 240 hours on mild steel. Along the cross cut section, rust is observed where the metal is exposed. But there is no considerable spreading of the rust from the cross cut section. Up to 240 hours of testing, the overall coating remains intact. The two resins prepared here in two different ways, but in terms of performance both are similar. We kept both these data to explore different ways of synthesis.

Water dip test result shows no spots, no blistering, no swelling after 168 hours. Water dip test was tested on aluminium substrate.
Cross cut adhesion test using Zehntner testing instrument (model no. ZMG 2151) shows 5B adhesion (as per ASTM D 3359) on mild steel, copper, galvanized iron, and aluminium substrate.
Flexibility test (as per ISO/IEC 17025 calibration lab) shows no crack or flake of the film around the bend part of the coating on mild steel, copper, galvanized iron, and aluminium substrate.
Pencil hardness test was performed following ASTM D3363 standard. Pencil hardness study on mild steel substrate shows that the coating has 3H pencil hardness.
Scratch resistance of the coating was tested using an automatic scratch tester (Sheen, ASTM D 7027). Observed scratch resistance was 3.5 kg. Scratch resistance test was done on mild steel.
Salt spray testing result (ASTM B117 standard) of as such clear film without any additive on mild steel shows no sign of rusting, flaking, or spots on the coating after 240 hours.
The particle size distribution is shown in the figure 3. Three different samples from example 1 are taken for the determination of particle size and their average are taken as average particle size. The average particle size is found to be in between 160 - 187 nm.

The FTIR data of the sample from example 1 are shown in Figure 4. The broad peak observed in between 3500 – 3200 cm-1 is mainly due to OH stretching frequency. The peak observed in between 3000 – 2800 cm-1 is mainly due to sp3 C-H stretching. The peak observed around 1726 cm-1 indicates the presence of carboxyl group or ester group. The peak found around 1606 cm-1 and at 1508 cm-1 may be due to aromatic C=C bending and N-O stretching respectively. The appearance of the peaks around 1448 cm-1 and around 1232 cm-1 are probably due to aliphatic C-H bending frequency. and C-O stretching of alkyl aryl ether respectively. The appearance of the peak around 1176 cm-1, around 1035 cm-1 and around 824 cm-1 are probably due to the C-OH stretching frequency, C-N stretching of amine and sp3 C-H bending respectively.

The SST (ASTM B117) data on galvanized iron (GI), copper, and aluminium panel are shown in figure 5. From the figure it is evident that, the copper and aluminium panel did not corrode at all upto 1000 hours. It means that the corrosion resistance of this coating on copper and aluminium are excellent. On GI panel, up to 480 hours, there is no corrosion observed. At 750 hours, some white spots are observed. The white line observed along cross cut. The white spots and lines are mainly due to the formation zinc oxide and zinc hydroxide. After 1080 hours, the spots are little prominent and white line thickness remains similar, does not get thick.
Thus the present invention enables successful preparation of one component environment friendly anticorrosive water based epoxy resin which upon curing provides clear film with average dry film thickness of 15-20 µm without any additive on mild steel, shows no sign of rusting, flaking, or spots on the coating after 240 hours. On galvanized iron, up to 480 hours no corrosion or rusting observed. On copper and aluminium panel no sign of corrosion (rusting, flaking or spots) observed up to 1080 hours. The resin is quick drying, flexible and has excellent adhesion on mild steel, copper, galvanized iron and aluminium surface. The developed synthesis method is robust and can be transferred for industrial manufacturing quite easily.
,CLAIMS:We claim

1.An anticorrosion water based epoxy resin comprising of
a water dispersible acrylated epoxy amine salt resin providing for a coating with average dry film thickness of 15-20 µm after curing which comprises of an acrylated and neutralized anticorrosion coating composition of an epoxy amine adduct of
a. bisphenol A based epoxy resin containing at least two epoxy groups, or cycloaliphatic epoxy resin containing at least two epoxy groups;
b. aliphatic or aromatic amines;
c. epoxy resin containing at least two aromatic rings;
d. epoxy resin containing at least one aromatic ring and one epoxy group as reactive epoxy diluents.

2. The anticorrosion water based epoxy resin as claimed in claim 1 wherein said epoxy amine adduct comprises
a. bisphenol A based epoxy resin containing at least two epoxy groups, or cycloaliphatic epoxy resin containing at least two epoxy groups (10- 50%)
b. aliphatic or aromatic amines (1 – 10%)
c. epoxy resin containing at least two aromatic rings preferably the phenol Novolac resin (1-20%)
d. epoxy resin (0.1-20 %) containing at least one aromatic ring and one epoxy group as reactive epoxy diluents;
which upon acrylation with suitable monomers (5-40%) followed by neutralization of free acids with amine provides said water dispersible acrylated epoxy amine salt.

3. The anticorrosion water based epoxy resin as claimed in anyone of claims 1-2 which is quick drying, flexible and having selectively excellent adhesion on mild steel, copper, galvanized iron and aluminium surface wherein
said bisphenol A based epoxy resin containing at least two epoxy groups having epoxy equivalent weight range in between 180 – 3000 g/eq. and is selected from YD-124, YD-125, YD-126, YD-127, YD-128, YD011x75, YD012x75, YD134x80, YD-901x75, YDF170, YDF-171, YDF172, YDF-173, YDFM-251, YDFM-270, YDFM-253, YDFM-261, YDFM-269, YDFM-262, YDFM- 250, YDFM-256, YD-901, YD-902, YD-903, YD-904, YD-905, YD-907, YD-909, YD-012, YD-013, YD-014, YD-942, YD-972, YD-017, YD-019, YD-010S; and

said cycloaliphatic epoxy resins have epoxy equivalent weight in the range of 180 – 720 g/equivalent includes ARCH-11, ARCH-12, ARCH-13, ARCH-13LV, ARCH-18.

4. The anticorrosion water based epoxy resin as claimed in anyone of claim 1-3 wherein said aliphatic and aromatic amine is/are selected from aniline, N- methyl aniline, triethylene tetramine, diethylene triamine, 2-butanamine, 3- methyl-1-butanamine, n-butylamine, n-octylamine, 2-aminoethanol, aminoethanoic acid, ethylene diamine, diethanolamine, 4-aminobenzoic acid, hexane-1,6-diamine, benzene-1,4-diamine, ethylamine, cyclohexyl amine, 2-methylbutylamine, (2-cyclooctylethyl)amine, (3-cyclopropylpentyl)amine, (3- metylpentyl)amine, (2-cycloheptylethyl)amine, tris-2-aminoethylamine, bis(3- aminopropyl)amine.

5. The anticorrosion water based epoxy resin as claimed in anyone of claim 1-4 wherein said Phenol Novolac resin is selected from ARPN-25, ARPN-36, ARPN-36 M 80, ARPN-53, ARPN-54, YDPN – 638LV, YDPN-661, YDPN-638X80; and
said acrylic monomers include 2-hydroxylethyl methacrylate, methyl methacrylate, acrylamide, N,N-dimethyl acrylamide, acrylic acid, styrene, glycidyl methacrylate, methacrylic acid, 2-(dimethylamino)ethyl methacrylate, 2-ethyl hexylacrylate, UL-513, butyl acrylate, butylmethacrylate, 1-vinyl-2-pyrrolidone, acrylonitrile, and vinyl acetate; and
said epoxy reactive diluents include RD-108, RD-109, RD-110, RD-118, RD-103, RD-111, RD-114, RD- 119, RD-121, RD-133, RD-113, RD-124, RD-129, RD-131, RD-104, RD-105, RD-106, RD-136, RD-138, RD-137, UL-513; and using ethylene glycol monobutyl ether as the solvent.

6. A method for the synthesis of anticorrosion water based epoxy resin as claimed in anyone of claims 1-5 comprises the steps of
a. providing bisphenol A based epoxy resin containing at least two epoxy groups, or cycloaliphatic epoxy resin containing at least two epoxy groups mixed in a solvent;
b. adding aliphatic or aromatic amines and reacted at elevated temperature;
c. adding epoxy resin containing at least two aromatic rings preferably, the phenol novolac resin;
d. adding another epoxy resin containing at least one aromatic ring and one epoxy group as reactive epoxy diluents;
heating at 80-100 oC for three more hours to make an epoxy amine adduct for obtaining therefrom said water dispersible acrylated epoxy amine salt resin providing for a coating with average dry film thickness of 15-20 µm after curing.

7. The method for synthesis as claimed in claims 6 wherein said synthesis of said epoxy amine adduct comprises the steps of
a. providing bisphenol A based epoxy resin containing at least two epoxy groups having epoxy equivalent weight range in between 180 – 3000 g/eq. (10- 50%), and/or cycloaliphatic epoxy resin containing at least two epoxy groups having epoxy equivalent weight in the range of 180 – 720 g/equivalent (10- 50%) mixing in ethylene glycol monobutyl ether as the solvent by heating at 80-100 oC;
b. adding aliphatic or aromatic amines (1 – 10%) and reacted at 80-100 oC for three hours;
c. adding epoxy resin containing at least two aromatic rings preferably, the phenol novolac resin (1-20%) and heating at 80-100 oC for three hours;

d. adding another epoxy resin (0.1-20 %) containing at least one aromatic ring and one epoxy group as reactive epoxy diluents in the reaction mixture and heating at 80-100 oC for three hours to provide said epoxy amine adduct.

8. The method for synthesis as claimed in claims 6-7 comprises
a. carrying out acrylation of as obtained epoxy amine adduct by reaction with suitable monomers (5-40 %) in the temperature range 60– 130 oC for three more hours;
wherein suitable monomer/s is/are selected from the list of monomers e.g. 2- hydroxylethyl methacrylate, methyl methacrylate, acrylamide, N,N-dimethyl acrylamide, acrylic acid, styrene, glycidyl methacrylate, methacrylic acid, 2- (dimethylamino)ethyl methacrylate, 2-ethyl hexylacrylate, UL-513, butyl acrylate, butyl methacrylate, 1-vinyl-2-pyrrolidone, acrylonitrile, and vinyl acetate;
followed by neutralizing the free acids of acrylated epoxy amine adduct with suitable amine provides the desired water dispersible acrylated epoxy amine salt resin.

Dated this the 6th day of June, 2024 Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)
IN/PA-199