Description:Fieldof theInvention
Present invention relates to preparation of a water dispersible cathodic electrodeposition (CED)epoxy resin to be used as first primer for automotive, automotive ancillaries, various metal coatings for protection and decoration purposes eliminating Bisphenol A with cardanol formaldehyde (CF). The resin does not require any solvent for processing and hence is highly user friendly with least hazards. Final E coat primer exhibits excellent corrosion resistance, and other performance properties required for said applications.

Backgroundof theInvention
Cathodic electrodeposition (CED) primeris themain corrosion resistance primer used for metal coatings in automotive, cars, trucks, two wheelers,three wheelers, tractors, ancillary parts, other metal substrates as body housing, fans, pipes, etc. It is a dip coating method that uses an electrical field to apply or deposit the conductive coating onto the part. The principle of the coating process is as follows:
a. Dissociation of finely dispersed binder containing ionisable groups,inaconductivemediumlikewaterundertheinfluence of DC power source.
b. Migration of chargedbinderionstowardsoppositely charged electrodes.
c. Thechargedbinderionscarrywithitthedispersedpigments and get deposited as uniform paint coating.
Environmental protection and sustainable products are need of the hour for coatings industry, which will be adapted to reduce use of petroleum source material and utilization of naturally occurring raw materials. Reduction of solvent % in ecoat (the cathodic electrodeposition coat) batch will be of great advantage to health of persons involved in coating process. It will also reduce fire hazard. Though amount of solvent used currently is low but further reduction without affecting the quality and performance will be an added advantage.

Majority of current CED binders use organic petroleum based rawmaterial. These resins are prepared by reaction of Diglycidyl ether of Bisphenol A (DGEBA) with free Bisphenol A, with small quantity of solvents, secondary amines, modified with blocked isocyanate, and inverted in water with acids. These binders are main source of corrosion protection in CED coatings. However it is reported and raises a concern that BPA is a xenoestrogen, exhibiting hormone-like properties that mimic the effects of estrogen in the body. Thus different efforts to replace BPA is prevalent in the prior art.
Cardanol is a naturally occurring material from cashew nut liquid shell. It has corrosion resistance property on account of phenolic OH- group present. Many prior patents and publications have reported on usage of cardanol for CED Application. Reference is invited for few of therelevant prior arts as follows:

Journal of Coatings Technology and Research (2011), 8(5), 563-575 – Cardanol formaldehyde resin was used to prepare selfcuring CED, baked at temperature of 1600 C/30 min achieved saltspray of 800 hours. The electrodeposited films of MECNs had good physical, chemical, and corrosion resistance properties, but demonstrated low resistance to xylene, in particular. The study emphasized the electro-deposition behavior and film properties of the prepared MECN resins as binders for CED coating formulations, which were self-curable without using any external crosslinker. The self-curing of the deposited films was achieved via a novel self-curing mechanism, i.e., one molecule chemistry through anionic polymerization. The prepared epoxide resins as MECNs could be cathodically electrodeposited as primer coat for the protection of metallic substrates against corrosion.

Journal of Applied Polymer Science (1990), 39(9), 1993-2004- Water-soluble Mannich bases were synthesized from cardbisphenol (cardanol-PhOH adduct) by Mannich reaction with diethanolamine or 2-(ethylamino)ethanol and were characterized by 1H NMR and 13C NMR spectroscopic methods. The effect of electrodeposition parameters on the film formation from binders and from pigmented compounds were studied. The polymers provided uniform coatings with good mechanical properties and the pigmented systems exhibited high resistance to organic solvents and good corrosion resistance properties.
Journal of Coatings Technology (1986), 58(738), 55-63 CODEN: JCTEDL; ISSN: 0361-8773-Novolak and resol resins based on maleinized cardanol were water-soluble after neutralization with dimethylethanolamine. Resols of maleinized cardanol gave coatings with better adhesion and scratch hardness than those from the novolak resins. The esterified product from resol of maleinized cardanol and maleinized (Search for A. Nemlekar Page 6 of 34 PPG Classification: Internal Business) linseed oil fatty acids gave electrodeposited films with good adhesion and scratch hardness to mild steel substrate. The Fe2O3-pigmented paints gave films with better adhesion, hardness, and chemical resistance than that obtained from unpigmented composition.
CN102807660 revealedwater-soluble resin for anodic electrophoretic coatings prepared from cardanol 56-63, 37% formaldehyde 7-12, hexamethylenetetramine 1.9-2.6, maleic anhydride 5-8, butanol 10-18, monoethanoamine 4.5-5.5 and toluene 3 parts. Thus, cardanol 57, 37% formaldehyde 12, hexamethylenetetramine 2.6, toluene 3 parts were heated at pH 8-8.5 at 100-138° C till the viscosity is 14-16 s at 25°, then added with maleic anhydride 8 parts, reacted at 150° for 20-30 min, mixed with butanol 15 parts, ethanolamine 5.4 parts to give a resin with PH 8-8.5.
Traversal of the prior art reveals that the majority of the disclosed resins for cathodic electrodeposition suffer from one or more drawback of lower corrosion resistance, lower solvent resistance, higher cost, use of hazardous raw materials including organic solvents etc. Thus there is an urgent need to develop a coating system which would address the shortcomings of the existing/reported coatings.

Objectsof theInvention
The primary objective ofthe present invention is to develop a polymeric resin having suitable epoxy equivalent weight window involving Diglycidyl ether of Bisphenol A (DGEBA) and Cardanol formaldehyde (CF)and eliminating completely or partially usage of Bisphenol A, to achieve requisite molecular weight, which when reacted with amine and inverted in water with acid should provide coatings with acceptable particle size, viscosity, supply NVM of 43 and excellent water solubility.

It is another objective of invention to develop said resin with higher epoxy equivalent weight and molecular weight to maximize corrosion resistance and solvent resistance properties.

Another objective of the present invention is to develop a suitable blocked crosslinker free of solvent so that incorporation of the same in the said polymeric resin wouldresult in coating free of solvent and thus no need to remove solvent by stripping.

Another objective of the present invention is to reduce/eliminate amount of flexiblisers for formulation to have lower cost.

It is another objective of the present invention not to use any solvent or solvent producing intermediate so that final resin will not have any solvent and batch will be stripping free.

It is another objective of the present invention that said CED primer based on resin should pass minimum 1200 hrs of salt spray with max 1 mm corrosion creep. @ 20-22 mic DFT.

Summaryof theInvention

In the primary embodiment the present invention is directed to provide a water dispersible epoxy binder for cathodic electrodeposition (CED) which is a reaction product of
a) a base resin obtained selectively of Diglycidyl ether of Bisphenol A (DGEBA) 8-20 wt% having extended molecular weight involving Cardanol formaldehyde (CF) 10-22.0 wt% and Ethoxylated Bisphenol A polyol 2-8 wt%maintaining epoxy equivalent weight of 1000—2000;
b) Blocked isocyanate 12-22 wt%;
e) secondary and multifunctional amines 0.5-3.0 wt%; and
f) Plasticizer 1-8.wt%; and
having Particle size in the range of 250-1800 A°, and viscosity in range of 50- 1500 cps on Brookfield viscometer.

Another embodiment of the present invention is directed to provide said water dispersible binder for cathodic electrodeposition (CED) wherein said base resin comprise of molecular weight (Mw)of 2952 to4650and obtained of said Cardanol formaldehyde (CF) having viscosity 1100- 2300 cps, hydroxy value 144- 182 and molecular weight in range of 1590-1750 g/Mol is a card-formaldehyde resin having 2-3 OH functionality and which is free of Bisphenol A.

Another embodiment of the present invention is directed to provide said water dispersible binder for cathodic electrodeposition (CED) wherein said blocked isocyanate crosslinker is a reaction product of Poly diphenyl methane diisocyanate and hydroxy functional solvents including Diethylene glycol monobutyl ether, Phenoxy propanol, butoxy ethanol, hexanol, and glycols as propylene glycol, ethylene glycol, diethylene glycol, in stochiometric ratios of 0.2-0.5, 0.1-0.5, 01.-0.4, with catalyst selected from dibutyl tin laurate, tertiary amine or dibutyl tin oxide (DBTO).

Yet another embodiment of the present invention is directed to provide said water dispersible binder for cathodic electrodeposition (CED) wherein said secondary and multifunctional amines include Aminopropyl diamine, Dimethyl amino propyl amine, N Methyl aminoethyl amine and Di ketamine; and said plasticizers include EFKA PL 5651 and TP-90B.

Further embodiment of the present invention is directed to provide saidwater dispersible binder for cathodic electrodeposition (CED) provides good film build up with dry film thickness(DFT) of 14-35 mic depending of voltage variation from 100-300V for excellent appearance and gloss, excellent corrosion resistance of 1400 hrs SST, 1000 hrs + humidity resistance, excellent solvent resistance properties with respect to Cold roll steel(CRS) substrate.

Another preferred embodiment of the present invention is directed to provide a process for the preparation of the water dispersible binder for cathodic electrodeposition (CED) comprises the steps of
(i) providing base resin by Epoxy molecular weight increase of Diglycidyl ether of Bisphenol A (DGEBA)as a base resin comprising Diglycidyl ether of Bisphenol A (DGEBA)8-20 wt%having extended molecular weight involving Cardanol formaldehyde (CF) 10-22 wt% and Ethoxylated Bisphenol A polyol 2-8 wt% maintaining epoxy equivalent weight of 1000—2000; followed by modification of the produced resin with blocked Crosslinker 12-22 wt%;
ii. carrying out amination of the thus obtained cross-linked base resin of step (i) above.
iii. subjecting to Dispersion /Inversion to thereby produce
solvent free emulsion having Particle size in the range of 250-1800 A°, and viscosity in range of 50- 1500 cps.

Another embodiment of the present invention is directed to provide said process wherein preparation of said resin involves
a. charging of Glycidyl ether of bisphenol A, Cardanol formaldehyde, ethoxylated bisphenol A Polyol, EFKA PL5651, and catalyst ETPPBr to the reactor in stoichiometric ratios of 1:0.3-0.8, 0.00-0.5, 0.2-4.00, 0.001-0.05;
b. heating the reactor to 140-1700 C, for 1-4 hr. to reach at desired epoxy equivalent weight of mixture to 1000-2000 and viscosity of P-Z2 @ 25 degC on GS, @ 50-60% NVM to provide the base resin;
c. adding further blocked crosslinker 15-45% to base resin in the said reactor at temperature of 80-130 degC and continuing further the reaction for 30min – 1 hr. yielding cross linked base resin.

Further embodiment of the present invention is directed to provide said process wherein said amination involves
adding secondary amines, multifunctional amines selected from Aminopropyl diamine, Dimethyl amino propyl amine, N Methyl aminoethyl amine, Di ketamine to the reactor having said cross linked base resin at temperature of 85-130 0C, wherein Amine to epoxy ratio is varied between 60-120%;and
continuing the reaction for 45min -3 hrs to arrive at a constant viscosity @50%-55 NVM of A-J, on Gardener scale.

Still further embodiment of the present invention is directed to provide said process wherein said dispersion/inversion involves
dropping of the post amination resin into the thin tank comprising water and acids including lactic acid, acetic acid, sulfamic acid at 75-100 rpm over 30 minutes period with a temperature of the thinning tank at 40-75°C;
holding the thin tank for an additional 60 minutes to neutralize amine by 10-80% and to maintain NVM of thin tank in the range of 55-65 %.
diluting the reaction mass to 35- 45% solids by adding water;
checking completion of inversion by standard test; and
providing the desired emulsion comprising particle size ranging from 250 to 1800 A°, and viscosity in range of 50- 1500 cps.

Another embodiment of the present invention is directed to provide said Diglycidyl ether of Bisphenol A (DGEBA) base resin suitable for producing water dispersible epoxy binder comprising of a reaction product of Diglycidyl ether of Bisphenol A (DGEBA) having extended molecular weight involving Cardanol formaldehyde (CF) and Ethoxylated Bisphenol A polyol maintaining epoxy equivalent weight of 1000—2000 and viscosity of P-Z2 @ 25 degC on GS, @ 50-60% NVM.
.
Yet another embodiment of the present invention is directed to provide said Diglycidyl ether of Bisphenol A (DGEBA) base resin Comprising
Diglycidyl ether of Bisphenol A (DGEBA) 33-55 Wt%
Cardanol formaldehyde (CF) 42-62 Wt% and
Ethoxylated Bisphenol A polyol 8-26%

Further embodiment of the present invention is directed to provide a process for manufacture of the Diglycidyl ether of Bisphenol A (DGEBA) base resin comprising:
i) providing in a reactor Glycidyl ether of bisphenol A, card-formaldehyde resin having 2-3 OH functionality, ethoxylated bisphenol A Polyol, EFKA PL5651, and catalyst selected from Ethyl triphenyl Phosphonium Iodide, Ethyl triphenyl Phosphonium bromide, Dimethyl benzyl amine preferably Ethyl triphenyl Phosphonium bromide (ETPPBr) in stoichiometric ratios of 1:0.3-0.8, 0.00-0.5, 0.2-4.00, 0.001-0.05;
ii) heating at temperature of 140-1700 C, for 1-4 hr. period to reach the desired epoxy equivalent weight of mixture to 1000-2000 and viscosity of P-Z2 @ 25 degC on GS, @ 50-60% NVM.

Still further embodiment of the present invention is directed to provide said process for deposition of coating involving the high performing binder for cathodic electrodeposition (CED) comprising the steps of
a. pretreatment – which includes cleaning and application of phosphate for the metal surface to be coated;
b. Electro-coating includes applying a regulated amount of voltage to coat the pretreated part with desired film thickness in the e-coat bath consisting 80-90% deionized water and 10-20% of resin and pigments;
c.Post rinse: After completion of electro coating process- coating is rinsed enhancing the quality of the coating and enabling recovery of excess paint;
D. Baking and curing: placing the coated region in a bake oven for 20 minutes with a temperature range of 165-177 degC preferably 177C to provide for the desired coating exhibiting good film build up, excellent appearance and gloss, excellent corrosion resistance of 1400 hrs SST, 1000 hrs + Humidity resistance and excellent solvent resistance properties.

DetailedDescriptionof theInvention

As stated hereinbefore present invention provides a high performing binder for cathodic electrodeposition (CED) employing Cardanol formaldehyde (CF) instead of Bisphenol A for epoxy extension. In the primary embodiment of the present invention Diglycidyl ether of Bisphenol A (DGEBA) is extended for molecular weight with Cardanol formaldehyde (CF), amines and modified with blocked isocyanate with the following composition.
a) DGEBA – 0.8-1.2 moles
b) CF -0.3-0.8 moles
c) Ethoxylated Bisphenol A – 0.00-0.5 moles
d) Blocked isocyanate– 0.6-1.00 moles
e) secondary and multifunctional amines– 0.2-0.5 moles
f) Plasticizer -0.00 -4.00

It has been observed that epoxy equivalent weight (EEW) iscritical for film performances and hence select EEW of 1000-2000grams was maintained for the intermediate adduct of DGEBA and cardanol formaldehyde resin for the present invention. This has profound effect on final polymer molecular weight, curing characteristics, corrosion resistance and solvent resistance.
Different batches of intermediate adducts having EEW from 950 to 2500 grams were synthesized and they were transformed into final coating following the invented protocol of the present invention. However it was observed that at lower EEW, performance properties of final electrodeposited coatings were much inferior and were not meeting specifications.
Table-1: Effect of EEW of the intermediate polymeric adduct on the final coating performance
Properties Electrocoat performance @ EEW around 950 Electrocoat performance @ EEW around 2000
Stability of emulsion Not stable continuous increase in viscosity at room temperature Stable ,
Particles size A° 500-1200, particle not stable with time 600-1300, Stable with time.
MEK double rub of deposited film Fails in 10 rubs Passes 20 Rubs
Molecular weight Mw. 1935 4124
Salt spray @ 1200 hrs Inferior Acceptable

It was also observed that EEW >2000 grams lead to much higher particle size causing setting tendencies in emulsion.

In another preferred embodiment the method developed for manufacturing of the desired high performing binder for cathodic electrodeposition involves the following steps:
i. Cardanol to Cardanol formaldehyde conversion;
ii. Production of solvent free Blocked Crosslinker;
iii. Epoxy molecular weight increase of Diglycidyl ether of Bisphenol A (DGEBA) using synthesized Cardanol formaldehyde;
iii. Modificationof resin of step iii with synthesized blocked Crosslinker;
iv. Amination; and
v. Dispersion /Inversion.
In another embodiment of the present invention use of cardanol formaldehyde for Cathodic electrocoat application as part and full replacement of Bisphenol A. (reducing BAL content substantially from coatings) providing the intermediate resin with substantially different chemical structure.
In another embodiment of the present invention Particle size of emulsion was maintained in range of 250-1800 A°, and viscosity was in range of 50- 1500 cps on Brookfield viscometer. It is known that there is an intimate relation between particle size and viscosity of the emulsion and with reduction of particle size viscosity increases (Effect of droplet size on the rheology of emulsions - Pal - 1996 - AIChE Journal - Wiley Online Library). Emulsions in accordance to the present invention having particle size out of the select range above does not meet the desired properties.
In another embodiment of the present invention no free organic solvent is used either for the preparation of the intermediates or preparation of the final CED resin. By this way present invention reduces the VOC level to zero and makes the coating much more user friendly and environment friendly.

Example-1
As stated hereinbefore Cardanol is a naturally occurring material from cashew nut liquid shell. It has corrosion resistance property because of the phenolic OH- group present in it. However. Cardanol is a monofunctional compound, hence a multifunctional CF was developed, and this resin was used as replacement to Bisphenol A for epoxy extension to get desired resin for CED coatings. Additionally presence of long carbon chain C17 H33 chain in cardanol formaldehyde helps to improve flexibility of the resulting resin.
Preparation of Cardanol formaldehyde (CF) from Cardanol.
Cardanol and Paraform are reacted in stoichiometric ratio of 1:0.5-0.9 in presence of acids such as p-toluene sulphonic acid/phosphoric/ oxalic acid/lactic acid and temperature of 100-1300 C, till the desired viscosity (1100- 2300 cps @ Brookfield viscometer Spindle 3, RPM 50) and hydroxy value (144- 182) and molecular weight in range of 1590-1750 g/Mol, (by GPC) are attained so as to achieve a card-formaldehyde having 2-3 OH functionality.
CF of 2-3 functionality was selected to have controlled growth of polymer during epoxy extension stage and avoid much hyper branched structure so as to have acceptable supply solids of 40-45% NVM of final resin.Higher functionalCF increased initial viscosity of CF much higher e.g. @ 1:0.9 equivalents of cardanol and Paraform, this higher functionality and viscosity led to higher viscosity during epoxy extension stage leading to lower NVM of resin and poor reaction control.

Preparation of Blocked crosslinker
Blocked crosslinker is produced by stoichiometric reaction of Poly diphenyl methane diisocyanate withhydroxy functional solvents such as Diethylene glycol monobutyl ether, Phenoxy propanol, butoxy ethanol, Hexanol, and glycols as propylene glycol, ethylene glycol, diethylene glycol, in stochiometric ratios of 0.2-0.5, 0.1-0.5, 01.-0.4, with a tin catalyst selected from Dibutyl tin oxide, dibutyl tin laurate, Tertiary amine preferably Dibutyl tin oxide(DBTO).
Reaction is carried out at temperature of 60-90 deg C, and continued till no free isocyanate is detected.

Preparation of Base resin by Epoxy Molecular weight increase
Glycidyl ether of bisphenol A, Cardanol formaldehyde as developed above, ethoxylated bisphenol A Polyol, EFKA PL5651, and catalystselected fromEthyl triphenyl Phosphonium Iodide, Ethyl triphenyl Phosphonium bromide, Dimethyl benzyl amine preferably Ethyl triphenyl Phosphonium bromide (ETPPBr) are charged to reactor in stoichiometric ratios of 1:0.3-0.8, 0.00-0.5, 0.2-4.00, 0.001-0.05.
Batch is heated at temperature of 140-1700C, for 1-4 hr. periodto reachthe desired epoxy equivalent weight of mixture to 1000-2000 and viscosity of P-Z2 @ 25 degC on GS, @ 50-60% NVM and MW ranging from 2952 to 4650.
ii. The Blocked crosslinker as produced above free of solvent is added to base resin 15-45% at temperature of 80-130 degC and the reaction continued for 30min – 1 hr.
Amination stage
Polymer obtained after reaction with crosslinker is further reacted at temperature of 85-130 0C with, secondary amines, multifunctional amines such as, Aminopropyl diamine, Dimethyl amino propyl amine, N Methyl aminoethyl amine, Di ketamine,wherein Amine to epoxy ratio is varied between 60-120%. Maintaining excess of epoxy equivalent to amine equivalents by 0.4-0.01 level, to get PH in the range of 4.5 – 6.5. (ACID MEQ/Base MEQ).Reaction continued for 45min -3 hrs to arrive at a constant viscosity @50%-55 NVM of O-Z, on Gardener scale.
Dispersion /Inversion
While batch is running at amination stage, a separate tank for thinning is charged with water and acids such as, lactic acid, acetic acid, formic acid, sulfamic acid etc.
The post amination resin is dropped into the thin tank at 75-100 rpm over 30 minutes. Thin tank temperature during the drop reaches40-75°C. The reaction continued in the thin tank for an additional 60 minutes to neutralize amine by 10-80% and to maintain NVM of thin tank in the range of 55-65 %.

Following said 60-minute hold, the reaction mass is diluted with water to35- 45% solids. Completion of the resin inversion is checked by standard procedure.
The final emulsion is having Particle size in the range of 250-1800 A°, and viscosity in range of 50- 1500 cps on Brookfield viscometer.

Example-2
As elaborated in details hereinbefore E-coating, also known as electrodeposition coating, is a method of painting that uses electrical current to deposit paint on a surface. The process works according to the principle that “opposites attract.” The process followed is depicted as a flow chart in figure 1 (Courtesy -PPG website)
Coating is carried out using following distinct steps of pretreatment, electro coating, post rinse, baking and curing.
a.pretreatment – metal is cleaned and a phosphate is applied to prepare the surface for application of the e-coat.
b. Electro-coating: coatings are applied to the pretreated metal in an electrocoat bath using precisely calibrated process control equipment. The e-coat bath consists of 80-90% deionized water and 10-20% paint solids. The deionized water acts as a carrier for the paint solids, which are under constant agitation. The solids consist of resin – the backbone of the final paint film, which provides corrosion protection, durability and toughness – and pigments, which contribute color and gloss.During the e-coat process, paint is applied to a part using a regulated amount of voltage to achieve the desired film thickness. Once the coating reaches the prescribed thickness, the part “insulates” and the coating process slows down.
c. Post rinse: After completion of electro coating process- coating is taken for rinsing. Rinsing enhances the quality of the coating and enables recovery of excess paint.
D. Baking and curing: Coated part exiting post-rinse phase, is placed in a bake oven that cures and cross-links the paint film to maximize its performance properties. The minimum bake time is 20 minutes with a part temperature range is 165-177 degC typically based on blocking solvent used in blocking isocyanate.
The performance properties of the coating are tested as per customer specification.
TESTING of resin in Electrocoat system
A Pigmented bath was prepared by mixing resin with pigment paste and water

Wt in gm
DI Water 55-65
Emulsion produced 30-40
Black Paste 3-8

Batch Parameters
Parameters Specification Exp CED Values
pH 5.5 - 6.4 5.90
Conductivity 1100 - 1800 1126
% NVM 13 - 17 14.28
% Pigment/Binder 0.100 - 0.140 0.108
% Butyl Cellosolve < 0.90 0.80


Different voltage study for Exp CED Bath
Bath temp : 32°C
Dip Time: 120 Sec (100" + 20" ramp time)
Curing 177°C/20' EMT
Substrate Applied Voltage(V) W1 W2 Residual Currrent Peak Current Coulombs drawn Coloumbic Yield(mg/C) Film Resistivity (ohm.cm) DFT (µ) Ra value
6"x3" CRS 100 63.3529 63.8077 0.04 0.50 13.6 33.4 525.0 14 - 15 0.40
6"x3" CRS 200 63.2089 63.8737 0.08 0.63 18.1 36.7 525.0 24 - 25 0.38
6"x3" CRS 300 63.9062 64.8697 0.09 0.59 24.4 39.5 700.0 34 - 35 0.32
CRS- Cold roll steel, W1 – weight of Panel with Pretreatment, W2- weight of panel after CED coating.
The table demonstrates that with application of higher voltage the difference between W1 and W2 is higher and accordingly dry film thickness (DFT) is also higher with similar roughness of films (Ra values).

Performance Testing:
Sr.No. Test Instrument Method Requirement Exp AGRP640
Mechanical Performance 177? C 20 min EMT
1 DFT DFT Meter Internal 18 - 22 22 - 24
2 Ra Value Mitutoyo Internal 0.35 µ or less 0.35 µ
3 Pencil Hardness Mitsubishi standard Internal 2H min Passes
4 MIBK Rub Test Manual Internal 10 double rubs Passes 10 DR
5 Cross-cut adhesion Adhesive tape ASTM D 3359 Passes 100/100 Passes 100/100
6 Gloss @ 60° Glossometer ASTM D 523 >35 39
7 Cupping test Erichsen cupping tester D 64384 6 mm min 8.2
8 Flexibility Conical Mandrel ASTM D 522 1/8" conical mandrel Passes with no defects
9 Impact Test Dupont impact tester ASTM D 256 500g, 1/2" dia, 50 cm ht Passes with no defects

Sr.No. Test DFT & Panel details Method Requirement Exp
Long termPerformance
1 Salt Spray (Phosphate treated CRS) 21 - 23µ
With PT ASTM B117 Apply salt spray for 1200hrs.
Apply tape test within 1 hour thereafter.
Maximum Creepage
1.5 mm on either side of Scribe line Passes 1400 hr SST , Corrosion Creep max 1.00 M
2 Humidity Resistance 21 - 23µ
With PT GMW 14729 No rust, No blisters, No adhesion failure after exposure of 1000 hrs. Passes 1300 hrs, No Blister, no rust.
3 Hot Water Resistance 21 - 23µ
With PT ASTM D 870 No blistering or rusting or loss of adhesion after exposure of 1000 hrs. Passes 1000 hs W/R

DFT is dry film thickness and Ra value is measurement of roughness of film, its measure of capability/ability of film to fill roughness of metal. Lower value is better, lower means primer has better filling hence topcoat appearance will be better.Gloss is dependent on customer specification. During evaluationof gloss in high gloss product, the invented coating provided higher gloss and appearance compared to standard product.
It is clearly evident from the table that resin in accordance to the present invention when evaluated in pigmented coating exhibitsacceptable curing properties, good film build DFT of 14-35 mic depending on voltage variation from 100-300V and good throwpower, great appearance, gloss, filling properties and excellent film integrity passing 20 MEK double rub solvent resistance properties.
The coating comprising the inventive resin passes all mechanical performance tests as Impact resistance, 1/8’’ conical mandrel, cupping up to 8.2 mm, perfect 100/100 adhesion.Also said coating offers excellent corrosion resistance passes 1400 hrs SST with 1 mm creep,@ ASTM B 117, excellent water and humidity resistance of 1000 hrs each.
For substantiation the coating in accordance to the present invention meets and in few cases exceeds requirements of standard Ecoat products for Automotive/industrial applications.

Thus the present invention provides a high performing binder for cathodic electrodeposition (CED) employing Cardanol formaldehyde (CF) instead of Bisphenol A for epoxy extension which helps in reduction on usage of petroleum source material and utilization of naturally occurring raw materials. As stated earlier that reduction of solvent % in ecoat (the cathodic electrodeposition coat) batch is of great advantage to health of persons involved in coating process. Present invention enables to provide said high performing binder avoiding use of any organic solvent for chemical reaction and production of CED resin which also reduces fire hazard. The binder in accordance to the present invention having a novel structure meets /exceeds specification of automotive coatings with Saltspray passing 1400 hrs, humidity resistance>1000 hrs, higher throw power etc. The process adopted for the synthesis of binder eliminates process of stripping and solvent employing high solid crosslinker.
, Claims:I/We Claim
1. A water dispersible epoxy binder for cathodic electrodeposition (CED) which is a reaction product of
a) a base resin obtained selectively of Diglycidyl ether of Bisphenol A (DGEBA) 8-20 wt% having extended molecular weight involving Cardanol formaldehyde (CF)10-22.0 wt%and Ethoxylated Bisphenol A polyol 2-8wt%maintaining epoxy equivalent weight of 1000—2000;
b) Blocked isocyanate12-22 wt%;
e) secondary and multifunctional amines 0.5-3.0 wt%; and
f) Plasticizer1-8.wt%; and
having Particle size in the range of 250-1800 A°, and viscosity in range of 50- 1500 cps on Brookfield viscometer.

2. The water dispersible binder for cathodic electrodeposition (CED) as claimed in claim 1 wherein said base resin comprise of molecular weight of 2952 to 4650 and obtained of said Cardanol formaldehyde (CF) having viscosity 1100- 2300 cps, hydroxy value 144- 182 and molecular weight in range of 1590-1750 g/Mol is a card-formaldehyde resin having 2-3 OH functionality and which is free of Bisphenol A.

3. The water dispersible binder for cathodic electrodeposition (CED) as claimed in anyone of claims 1 or 2 wherein said blocked isocyanate crosslinker is a reaction product of Poly diphenyl methane diisocyanate and hydroxy functional solvents including Diethylene glycol monobutyl ether, Phenoxy propanol, butoxy ethanol, hexanol, and glycols as propylene glycol, ethylene glycol, diethylene glycol, in stochiometric ratios of 0.2-0.5, 0.1-0.5, 01.-0.4, with catalyst selected from dibutyl tin laurate, Tertiary amine or Dibutyl tin oxide (DBTO).

4. The water dispersible binder for cathodic electrodeposition (CED) as claimed in anyone of claims 1 to 3 wherein said secondary and multifunctional amines include Aminopropyl diamine, Dimethyl amino propyl amine, N Methyl aminoethyl amine and Di ketamine; and said plasticizer include EFKA PL 5651 and TP-90B.

5. The water dispersible binder for cathodic electrodeposition (CED) as claimed in claims 1-4 provides good film build up with dry film thickness(DFT) of 14-35 mic depending of voltage variation from 100-300V for excellent appearance and gloss, excellent corrosion resistance of 1400 hrs SST, 1000 hrs + humidity resistance, excellent solvent resistance properties with respect to Cold roll steel(CRS) substrate.

6. A process for the preparation of the water dispersible binder for cathodic electrodeposition (CED) as claimed in anyone of claim 1-5 comprises the steps of
(i) providing base resin by Epoxy molecular weight increase of Diglycidyl ether of Bisphenol A (DGEBA) as a base resin comprising Diglycidyl ether of Bisphenol A (DGEBA)8-20 wt%having extended molecular weight involving Cardanol formaldehyde (CF) 10-22 wt% and Ethoxylated Bisphenol A polyol 2-8wt% maintaining epoxy equivalent weight of 1000—2000; followed by modification of the produced resin with blocked Crosslinker12-22 wt%;
ii. carrying out amination of the thus obtained cross-linked base resin of step (i) above.
iii. subjecting to Dispersion /Inversion to thereby produce
solvent free emulsion having Particle size in the range of 250-1800 A°, and viscosity in range of 50- 1500 cps.

7. The process as claimed in claim 6 wherein preparation of said resin involves
a. charging of Glycidyl ether of bisphenol A, Cardanol formaldehyde, ethoxylated bisphenol A Polyol, EFKA PL5651, and catalyst ETPPBr to the reactor in stoichiometric ratios of 1:0.3-0.8, 0.00-0.5, 0.2-4.00, 0.001-0.05;
b. heating the reactor at 140-1700 C, for 1-4 hr. to reach the desired epoxy equivalent weight of mixture to 1000-2000 and viscosity of P-Z2 @ 25 degC on GS, @ 50-60% NVM to provide the base resin;
c. adding further blocked crosslinker 15-45% to base resin in the said reactor at temperature of 80-130 degC and continuing further the reaction for 30min – 1 hr. yielding cross linked base resin.

8. The process as claimed in claim 6-7 wherein said amination involves
Adding secondary amines, multifunctional amines selected from Aminopropyl diamine, Dimethyl amino propyl amine, N Methyl aminoethyl amine, Di ketamine to the reactor having said cross linked base resin at temperature of 85-130 0C, wherein Amine to epoxy ratio is varied between 60-120%;and
Continuing the reaction for 45min -3 hrs to arrive at a constant viscosity @50%-55 NVM of A-J, on Gardener scale.

9. The process as claimed in anyone of claims 6 - 8 wherein said dispersion/inversion involves
dropping of the post amination resin into the thin tank comprising water and acids including lactic acid, acetic acid, sulfamic acid at 75-100 rpm over 30 minutes period with a temperature of the thinning tank at 40-75°C;
holding the thin tank for an additional 60 minutes to neutralize amine by 10-80% and to maintain NVM of thin tank in the range of 55-65 %.
diluting the reaction mass to 35- 45% solids by adding water;
Checking completion of inversion by standard test; and
providing the desired emulsion comprising particle size ranging from 250 to 1800 A°, and viscosity in range of 50- 1500 cps.

10. Diglycidyl ether of Bisphenol A (DGEBA) base resin suitable for producing water dispersible epoxy binder as claimed in anyone of claims 1 to 5 comprising of a reaction product of Diglycidyl ether of Bisphenol A (DGEBA) having extended molecular weight involving Cardanol formaldehyde (CF) and Ethoxylated Bisphenol A polyol maintaining epoxy equivalent weight of 1000—2000 and viscosity of P-Z2 @ 25 degC on GS, @ 50-60% NVM.
11. The Diglycidyl ether of Bisphenol A (DGEBA) base resin as claimed in claim 10 Comprising
Diglycidyl ether of Bisphenol A (DGEBA)33-55 Wt%
Cardanol formaldehyde (CF) 42-62 Wt% and
Ethoxylated Bisphenol A polyol 8-26%

12. A process for manufacture of the Diglycidyl ether of Bisphenol A (DGEBA) base resin as claimed in anyone of claims 10 or 11 comprising:
i) providing in a reactor Glycidyl ether of bisphenol A, card-formaldehyde resin having 2-3 OH functionality, ethoxylated bisphenol A Polyol, EFKA PL5651, and catalyst selected from Ethyl triphenyl Phosphonium Iodide, Ethyl triphenyl Phosphonium bromide, Dimethyl benzyl amine preferably Ethyl triphenyl Phosphonium bromide (ETPPBr) in stoichiometric ratios of 1:0.3-0.8, 0.00-0.5, 0.2-4.00, 0.001-0.05;
ii) heating to temperature of 140-1700 C, for 1-4 hr. period to reach at desired epoxy equivalent weight of mixture to 1000-2000 and viscosity of P-Z2 @ 25 degC on GS, @ 50-60% NVM.

13. A process for deposition of coating involving the high performing binder for cathodic electrodeposition (CED) as claimed in claims 1-4 comprising the steps of
a. pretreatment – which includes cleaning and application of phosphate for the metal surface to be coated;
b. Electro-coating includes applying a regulated amount of voltage to coat the pretreated part with desired film thickness in the e-coat bath consisting 80-90% deionized water and 10-20% of resin and pigments;
c.Post rinse: After completion of electro coating process- coating is rinsed enhancing the quality of the coating and enabling recovery of excess paint;
D. Baking and curing: placing the coated region in a bake oven for 20 minutes with a temperature range of 165-177 degC preferably 177C to provide for the desired coating exhibiting good film build up, excellent appearance and gloss, excellent corrosion resistance of 1400 hrs SST, 1000 hrs + Humidity resistance and excellent solvent resistance properties.

Dated this the13th day of August, 2022 Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)
IN/PA-199