Field of invention
The present invention relates to a water based air drying epoxy ester for coating
applications and the process for preparation thereof. More particularly it relates to
5 the development of water based air drying binder system for use in anticorrosive
coating applications.
Backmound of the invention
10 Organic coatings are widely employed for corrosion protection of metallic
structures. Organic solvents are often used for adjusting the consistency to
increase the ease of handling and application. These volatile organic solvents
evaporate in atmosphere on application of coating on the substrate and cause
atmospheric pollution. Due to the imposition of increased legislative restrictions
15 on the emission of organic materials in atmosphere, water-borne coatings are
finding more and more importance in coating applications considering the need to
avoid/minimize the use of volatile organic compounds (VOC) in coating
formulation. The main advantages of using water as a solvent is primarily lies in
that, it is non-toxic, non-flammable and renewable. US Patent 4273921 describes
20 a water soluble epoxy resin. The use of such a system in coating for marine
applications is not reported.
US4273921 and US4346044 describe the water soluble air drying alkyd for nonyellowing
lacquers. This invention is focused on lacquer for topcoat applications.
25 US4939189 described water borne coating composition with dispersed pigments.
However this coating needs high temperature baking after coating application by
electrodeposition. US5137965 described process for water based alkyd resins
from melanised fatty acids and coating formulations thereof. This invention is on
pure alkyd resins. US6787190 teaches water based polyurethane paint
30 composition. This coating needs high temperature baking after coating application
by electro deposition.
Progress in Organic Coatings 49 (2004) Giindiizb et a1 reported the use of water
based resins based on polyurethane dispersions for coatings applications.
However, these coatings were baked at high temperature which is not viable in the
case of extremely large structures like naval platforms,
5
US2010/0048812 described a water based urethane based alkyd resin, this
invention utilizes isocyanates which are known for their toxicity and limited shelf
life hence need at most care while handling and storage. US2011/0195195
describes the water based paints based on epoxy resins. This utilized water based
10 epoxy resin cured with amine hardener. This is a two component system where
base hardener are mixed just before application and consumed with in its
stipulated pot life. In addition, inventions described in prior art utilized amines to
neutralize acid functionalized resins, in some cases free amines used for
neutralization are volatile in nature, which leads to poor stability of resin.
15
Organic coatings are widely employed for corrosion protection of structures.
Organic solvents often used for adjusting the consistency to increase the ease of
handling and application. These organic solvents evaporate into atmosphere on
application of coating on the substrate and cause atmospheric pollution. Use of
20 solvent free coatings can reduce the emission of organic solvents however, use of
such coatings is limited due to high viscosity of binders used in such coatings.
Most of the water based systems described in prior art need either high
temperature baking or based on alkyd. High temperature baking is a limitation in
25 the case of large structures such as Naval platforms. Alkyd resins provide tough
air drying films and have limited corrosion resistance.
In light of the above disadvantages there remains a need to produce a water based
system which overcome the above drawback and provide a water based system for
30 coating application devoid of the above disadvantages.
Epoxy esters are known for their superior corrosion resistance compared to pure
alkyd and Epoxy systems are known for their good corrosion resistance.
The present inventors have surprisingly developed a water based air drying epoxy
5 ester based on unsaturated fatty acids which is further neutralized essentially with
phosphoric acid, having enhanced performance through in-situ formation of iron
phosphate passive film at metal coating interface which improves the adhesion
and other performance properties of the coating.
10 The present inventors have synthesized water based air drying epoxy ester having
improved toughness and air drying properties from unsaturated fatty acids and
good corrosion resistance, improved adhesion and mechanical properties from
epoxy resins. Further the resins were neutralized essentially with phosphoric acid
which form passive iron-phosphate film on metal substrate and enhances the
15 adhesion and other performance properties.
The present invention provides a water based air drying epoxy ester based on
unsaturated fatty acids which is further neutralized essentially with phosphoric
acid which effectively enhances adhesion and other performance properties.
20
The present inventors have developed a water based air drying epoxy ester resin
which is further diluted with water to adjust the viscosity of the resin and
consistency to increase the ease of handling and application, which also avoid the
use of an organic solvents which evaporates in atmosphere on application of the
25 coating on the substrate and cause atmospheric pollution.
The present invention provides a water based air drying epoxy ester based on
unsaturated fatty acids which is neutralized essentially with phosphoric acid
having improves toughness, air drying properties, superior corrosion resistance,
30 enhance adhesion properties and other performance properties. The present
invention also eliminates the problems associated with prior art coatings
employed for corrosion protection of structures.
The present invention provides water based systems which do not require high
temperature for drying and overcome the drawback in case of coating known in
the literature which require high temperature baking for drying which is a
limitation in the case of large structures such as naval platforms.
5
The water based air drying epoxy ester for coating application being a system
which can be dried at ambient temperature, thus finds its application in coating of
large structures such as naval platforms which is not possible in case of the
organic coatings known in the prior art.
10
Obiects of the invention
It is an object of the present invention to synthesize a water based air drying
binder for use in anticorrosive coating and to developed its method of preparation.
15
It is another object of the present invention to synthesize a water based air drying
binder for use in anticorrosive coating which is environmentally friendly.
It is another object of the present invention to synthesize a water based air drying
20 binder for use in anticorrosive coating which utilizes the linseed oil fatty acid
(LOFA), Tung oil fatty acid (TOFA), dehydrated Castrol oil fatty acid (DCOFA)
or Soya oil fatty acid (SOFA) which can form tough adherent films through
oxidative polymerization without need of any external catalyst or curing agent.
25 It is another object of the present invention to synthesize a water based air drying
epoxy ester having improved toughness and air drying properties from unsaturated
fatty acids.
It is another object of the invention to synthesize a water based air drying binder
30 for use in anticorrosive coating which utilizes aliphatic/aromatic epoxy resin for
improved adhesion, corrosion resistance and mechanical properties.
It is further object of the present invention is to synthesize a water based air
drying binder for use in anticorrosive coating, which utilizes essentially
phosphoric acid for neutralization to form passive iron-phosphate film on metal
substrate and enhances the adhesion and other performance properties.
It is yet another object of the present invention to synthesize a water based air
drying binder for use in anticorrosive coating, which utilizes water as a solvent to
avoid the use of volatile organic component in the paint.
Summarv of the invention
According to an aspect of the present invention, there is provided water based air
drying binder comprising:
i) Epoxy resin having an epoxy equivalent weight in the range
of 190 to 700;
ii) Fatty acid capable of undergoing oxidative polymerization
without need of any external catalyst or curing agent;
iii) Phosphoric acid for neutralization;
iv) Drier blend of lead and cobalt in the ratio 10:l;
v) Water for dilution.
According to another aspect of the present invention, there is provided a process
for the preparation of water based air drying binder comprising the steps of:
i) Reacting epoxy resin having an epoxy equivalent weight in the
range 190 to 700 with fatty acid in presence of a catalyst at
temperature 60°C to 1 40°C to obtain a synthesized resin;
ii) Reacting synthesized resin obtained in the step (i) with arnine in
mole ratio 0.5 to 1 mole at temperature between 45°C to 105OC,
more preferably at temperature between 65°C to 85°C for 20
minutes to 100 minutes;
iii) Neutralizing the reaction product obtained in step (ii) essentially
with phosphoric acid;
iv) Adding drier blend of lead (0.05 to 0.5% of metal) and cobalt
(0.005 to 0.05 % of metal) in the ratio 10:I (Lead: Cobalt) to the
reaction product obtained in step (iii) and mixing for 1 hour to 3
hours;
v) Diluting the reaction product obtained in step (iv) with water to
obtain water based air drying binder.
10 Description of the invention
The present invention relates to a water based air drying epoxy ester for coating
applications and the process for preparation thereof. More particularly it relates to
the development of water based ambient drying binder system for use in
15 anticorrosive coating applications.
"Water based air drying binder" means water based air drying epoxy ester of the
present invention.
20 In an embodiment of the present invention there is provided a water based air
drying binder system based on fatty acid and epoxy resin.
Fatty acid employed in the present invention is selected from the group consisting
of Linseed oil fatty acid (LOFA), Tung oil fatty acid (TOFA), Dehydrated Castrol
25 oil fatty acid (DCOFA), Soya oil fatty acid (SOFA), preferably is selected from
LOFA, DCOFA & TOFA and more preferably TOFA is selected to employed in
the present invention.
Epoxy resin employed in the present invention is selected from aliphatic or
30 aromatic epoxy resin. Example: Diglycidyl ether of bis phenol 'A', diglycidyl
ether of neopentyl glycol etc, Epoxy Phenolic Novolac resin.
Neutralization of the synthesized resin which is the reaction product of fatty acid
with epoxy resin is carried out essentially with phosphoric acid.
In another embodiment of the present invention, there is provided water based air
5 drying binder comprising:
i) Epoxy resin having an epoxy equivalent weight in the range
of 190 to 700;
ii) Fatty acid capable of undergoing oxidative polymerization
without need of any external catalyst or curing agent;
10 iii) Phosphoric acid for neutralization;
iv) Drier blend of lead and cobalt in the ratio 10: 1;
v) Water for dilution.
In a preferred embodiment of the present invention there is provided a water
15 based air drying binder system based on Linseed oil fatty acid (LOFA) and epoxy
resin which is neutralized essentially with phosphoric acid, having improved
toughness, air drying properties, superior corrosion resistance, enhance adhesion
properties and other performance properties.
20 In yet another embodiment of the present invention there is provided a process for
preparation of water based ambient curing polymeric binder comprising reacting
fatty acid with epoxy resin, with epoxy equivalent weight in the range 190-700 in
presence of catalyst such as p-toluene sulphonic Acid (p-TSA)/tri phenyl
phosphine at temperature 60°C to 140°C to obtain a synthesized resin. The
25 reaction is monitored by FTIR till acid group disappeared in FTlR spectra.
The synthesized resin is reacted with amine such as Di-Ethanol Amine(DEA), Nmethyl
Ethanol Amine (NMEA), Di Ethanol Tetra Amine(DETA) etc. in mole
ratio (0.5-1 mole) at temperature 45°C to 105"C, preferably DEA, NMEA more
30 preferably DEA at 65°C to 85°C for 20 minutes to 100 minutes.
Further the reaction product was neutralized essentially with phosphoric acid
solution by stirring at high speed from 1-6 hours. Further drier blend lead (0.05 to
0.5 % of metal), cobalt (0.005 to 0.05 % of metal) in the ratio 10:l ratio (Lead:
cobalt) was added to resin and mixed for about 1 hour to 3 hours. The viscosity,
non-volatile matter (NVM) of resin was adjusted by diluting with water.
5 In a further embodiment of the present invention, there is provided a process for
the preparation of water based air drying binder con~prisingth e steps of:
i) Reacting epoxy resin having an epoxy equivalent weight in the
range 190 to 700 with fatty acid in presence of a catalyst at
temperature 60°C to 1 40°C to obtain a synthesized resin;
ii) Reacting synthesized resin obtained in the step (i) with amine in
mole ratio 0.5 to 1 mole at temperature between 45°C to 105OC,
more preferably at temperature between 65°C to 85OC for 20
minutes to 100 minutes;
iii) Neutralizing the reaction product obtained in step (ii) essentially
with phosphoric acid;
iv) Adding drier blend of lead (0.05 to 0.5% of metal) and cobalt
(0.005 to 0.05 % of metal) in the ratio 10:l (Lead: Cobalt) to the
reaction product obtained in step (iii) and mixing for 1 hour to 3
hours;
v) Diluting the reaction product obtained in step (iv) with water to
obtain water based air drying binder.
25 The reaction scheme for the process for the preparation of water based air drying
binder is represented by scheme I.
Scheme I:
Epoq Ester
60°C,l hrs
?OH
HN
icm
V DE A
Epoxy Resin 140°C
Amine Functionalized Epoxy Ester
p-TSA Fa@ Acid
OH Water based epov ester
Neutralization by
phosphoricacid and water
H91.w
2 6 MLR 28\4
The synthesized resin was evaluated for its performance by apulying on a
burnished mild steel panel by brush to obtain a drv film thickness of "IOOu,
coated mild steel specimen were tested for adhesion strength and corrosion
resistance prouerties.
5
Table-1: Resin Based on LOFA Neutralized with Phosphoric acid, Lactic
Acid, Acetic acid and Hydrochloric Acid.
10 Table 2: Resin Based on TOFA Neutralized with Phosphoric acid, Lactic
Test Characteristic
Adhesion
Scratch Hardness
Impact test, Ikg,
60cm height, .5cm
tip dia
Drying Time
(a)Surface dry
(b)Hard dry
Flexibility on
cylindrical mandral
(1 14 inch dia)
Acid, Acetic acid and Hvdrochloric Acid.
Test I Phosphoric Acid ( Lactic acid Acetic acid I Hvdrochloric (
Phosphoric Acid
8.5 MPa
Pass (up to 1 kg)
Pass (No cracks
and delamination
of film observed)
1 hour
24 hours
Pass (no sign of
crack)
I I I Scratch Hardness / Pass (up to 1.5 kg) / Pass (up t'o I kg) /I Pass (up to 1.2kg) II Pass (up to I kg) 1
Lactic acid
5.7 MPa
Pass (up to
800gm)
Fail (cracks and
delamination of
film observed)
1 hour
24 hours
Pass (no sign of
crack)
Characteristic
Adhesion
Acetic acid
6.1 MPa
Pass (up to
800gm)
Fail (cracks and
delamination of
film observed)
1 hour
24 hours
Pass (no sign of
crack)
10.8 MPa
Impact test, I kg,
60cm height, .5cm
tip dia
Drying Time
Hydrochloric
Acid
5.4 MPa
Pass (up to
700gm)
Fail (cracks and
delamination of
film observed)
1 hour
24 hours
Pass (no sign of
crack)
(a)Surfacedry
8.2 MPa
Pass (No cracks and
delamination of
film observed)
1 hour
8.5
Fail (cracks and
delamination of
film observed)
Acid
7.8
I hour
Fail (cracks and
delamination of
film observed)
Fail (cracks and
delamination of
film observed)
1 hour 1 hour
2 6 MAR 28\1
Table 3: Resin Based on DCOFA Neutralized with Phosphoric acid, Lactic
Acid, Acetic acid and Hvdrochloric Acid.
5
24 hours
Pass (no sign of
crack)
Table 4: Resin Based on SOFA Neutralized with Phosphoric acid, Lactic
22 hours
Pass (no sign of
crack)
Test
Characteristic
Adhesion
Scratch Hardness
Impact test, Ikg,
60cm height,.5 cm
tip dia
Drying Time
(a)Surface dry
(b)Hard dry
Flexibility on
cylindrical
mandral (I14 inch
dia)
Acid, Acetic acid and Hvdrochloric Acid.
24 hours
Pass (no sign of
crack)
(b) Hard dry
Flexibility on
cylindrical
mandral (114 inch
dia)
Test I Phosphoric Acid I Lactic acid Acetic acid I Hvdrochloric I
20 hours
Pass (no sign of
crack)
Phosphoric Acid
9.5MPa
Pass (up to 800 gm)
Pass (No cracks and
delamination of
film observed)
1 hour
24 hours
Pass (no sign of
crack)
Lactic acid
7.4 MPa
Pass (up to 600g)
Fail (cracks and
delamination of
film observed)
1 hour
28 hours
Pass (no sign of
crack)
Characteristic
Adhesion
Scratch Hardness
Acetic acid
7.6
Pass (up to 700g)
Fail (cracks and
delamination of
film observed)
1 hour
26 hours
Pass (no sign of
crack)
9.2 MPa
Hydrochloric
Acid
6.9
Pass (up to 600)
Fail (cracks and
delamination of
film observed)
1 hour
28hours
Pass (no sign of
crack)
Pass (up to 700 gm)
7.4 MPa
Pass (up to 400g)
7.6
Acid
6.9
Pass (up to 500g) Pass (up to 400)
2 6 MAR 2011
From the Table-1 to Tabled it is observed that film prepared from resin based on
LOFA, TOFA, DCOFA and SOFA neutralized with phosphoric acid shows
Impact test, I kg,
60cm height, .5cm
tip dia
Drying Time
(a)Surfacedry
(b)Hard dry
Flexibility on
cylindrical
mandral (114 inch
dia)
superior performance compared to that of lactic acid, acetic acid and hydrochloric
Fail (cracks and
delamination of
film observed)
l hour
30 hours
Pass (no sign of
crack)
Pass (No cracks and
delamination of
film observed)
I hour
26 hours
Pass (no sign of
crack)
5 acid. This is attributed to the formation of iron phosphate passive film at metal
coating interface which enhances adhesion and other performance properties.
Fail (cracks and
delamination of
film observed)
l hour
28 hours
Pass (no sign of
crack)
Table 5: Resin Based on LOFA, TOFA, DCOFA & SOFA neutralized with
Phos~horica cid
10
I Test LOFA TOFA DCOFA SOFA
Fail (cracks and
delamination of
film observed)
1 hour
30hours
Pass (no sign of
crack)
Scratch
Hardness
Impact test, lkg,
1 OOcm
height,.5cm tip
Characteristic
Adhesion
cracks and
delamination of
8.5 MPa
dia
Drying Time
10.8 MPa
(ajsurface dry
film observed)
l hrs I lhr I lhr
I lhrs ,
(b)Hard dry
Flexibility on
cylindrical
mandral (I14 inch
dia)
9.5 MPa 9.2 MPa
film observed) I film observed)
24 hrs
Pass (no sign of
crack)
- -
film observed)
20 hrs
Pass (no sign of
crack)
24hrs
Pass (no sign of
crack)
26 hrs
Pass (no sign of
crack)
From Table-5 it is seen that the coating films prepared from resins based on
TOFA (Preferred embodiment of the present invention) showing superior
performance compared LOFA, DCOFA and SOFA. This can be attributed to the
higher crosslink density resulting from the large number of conjugated double
5 bonds present in TOFA.
Experimental Data:
Resistance to artificial sea water salt spray test:
10
Burnished Mild steel panel of dimension 150mm x lOOmm x 1.51nm cleaned with
Xylene. One coat of the paint was applied (thickness 4025 microns) with brush on
panel and allowed to dry for four days. After drying the edges of the panels were
sealed with epoxy resin to prevent corrosion at edges and exposed to artificial sea
15 water salt spray test as per IS: 101 (Part 6Isec 1) -1988.0bservation of the panels
were made regularly for blistering and corrosion.
Adhesion test
20 Burnished Mild steel panel of dimension 150mm x lOOmm x 1.5mm cleaned with
Xylene. One coat of the coating was applied (thickness 405 5 microns) with brush
on panel and allowed to dry for four days. After drying quantitative adhesion test
was carried out on Lloyd LR-30K adhesion tester.
25 Drying time
Burnished Mild steel panel of dimension 150mm x lOOmm x 1.5mm cleaned with
. Xylene. One coat of the coating was applied (thickness 402 5 microns) with brush
on panel and allowed to dry for four days. The drying time test was carried out as
30 per specification IS: 101 (part 31Sec 2)-1986- Method of sampling and test for
paints, varnishes and related products.
For storage stability Prepared resins was kept for six months at ambient
temperature. Properties like viscosity, settling /separation, fouling. and
color/appearance is given below in table - 6.
5 Table 6- Storage Stability of Resin Based on LOFA, TOFA, DCOFA and
SOFA neutralized with Phos~horic acid, after 6 months under
ambient storage conditions.
Test
Characteristic
Viscosity at
25°C
Settling1
Separation
Fouling
Color/
Appearance
Separation Separation No Separation Separati I No I No I No
I Fouling
Pale 1 Pale I Pale 1 Pale
Free from
Fouling
Yellow 1 Yellow 1 Yellow 1 Yellow
Separation Separation 1 Separation I Separation I
Free from
Fouling
Free from
Fouling
Free from
Fouling
The following examples are meant to illustrate the present invention. The
examples are presented to exemplify the invention and are not to be considered as
limiting the scope of the invention.
15
on
Free
from
Pale
Yellow
EXAMPLES
Free from
Fouling
Exam~le-1:P reparation of Resin with TOFA and phosphoric acid
Pale
Yellow
20 A water based ambient curing polymeric binder material (i.e. Water based air
drying binder) based on TOFA was synthesized. 1 mole of fatty acid (TOFA) was
reacted with 0.5 to 1 mole of epoxy resin with epoxy equivalent weight of about
450 in presence of catalyst such as p-TSA at temperature about 140°C, The
reaction was monitored by FTIR. The synthesized resin is reacted with amine
Free from
Fouling
Free from
Fouling
Pale
Yellow
Pale
Yellow
DEA, in mole ratio (0.5 to 1 mole) at temperature 65+2"C for I hour. Further the
reaction product was neutralized essentially with phosphoric acid solution by
steering at high speed from 4 to 6 hrs. Further drier blend of lead (0.05 to 0.5 % of
metal), cobalt (0.005 to 0.05 % of metal) in the ratio 10:l (Lead: cobalt) was
5 added to resin and mixed for about Ihour. The viscosity, NVM of resin was
adjusted by using water. The synthesized resin was evaluated for its performance
by applying on a burnished mild steel panel by brush to obtain a dry film
thickness of -1 OOp, coated mild steel specimen were tested for adhesion strength
and corrosion resistance properties.
10
Example-2: Preparation of Resin with DCOFA and phos~horica cid.
Polymeric binder material (i.e. Water based air drying binder) based on DCOFA
was synthesized. I mole of fatty acid DCOFA was reacted with epoxy resin with
15 epoxy equivalent weight about 450 in presence of catalyst such as PTSA at
temperature 140°C, The reaction was monitored by FTIR. The synthesized resin is
reacted with amine such as DEA, in mole ratio (0.5 to 1 mole) at temperature 65
to 85 "C for 1 hour. Further the reaction product was neutralized essentially with
phosphoric acid solution by stirring at high speed from 4 to 6 hrs. Further drier
20 blend of lead (0.05 to 0.5 % of metal), cobalt (0.005 to 0.05 % of metal) in the
ratio 10:1 (Lead: cobalt) was added to resin and mixed for about 1 hour. The
viscosity, NVM of resin was adjusted by using water. The synthesized resin was
evaluated for its performance by applying on a burnished mild steel panel by
brush to obtain a dry film thickness of -loop, coated mild steel specimen were
25 tested for adhesion strength and corrosion resistance properties.
Example-3: Preparation of Resin with SOFA and phosphoric acid.
A water based ambient curing polymeric binder material (i.e. Water based air
30 drying binder) based on SOFA was synthesized. 1 mole of fatty acid (SOFA) was
reacted with 0.5 to 1 mole of epoxy resin with epoxy equivalent weight of about
450 in presence of catalyst such as p-TSA at temperature about 140°C, The
reaction was monitored by FTIR. The synthesized resin is reacted with amine
DEA, in mole ratio (0.5 to I mole) at temperature 6552°C for 1 hour. Further the
reaction product was neutralized essentially with phosphoric acid solution by
5 steering at high speed from 4 to 6 hrs. Further drier blend of lead (0.05 to 0.5 % of
metal), cobalt (0.005 to 0.05 % of metal) in the ratio 10:l (Lead: cobalt) was
added to resin and mixed for about Ihour. The viscosity, NVM of resin was
adjusted by using water. The synthesized resin was evaluated for its performance
by applying on a burnished mild steel panel by brush to obtain a dry film
10 thickness of -1 OOp, coated mild steel specimen were tested for adhesion strength
and corrosion resistance properties.
Example-4: Pre~arationo f Resin with LOFA and phosphoric acid.
15 A water based ambient curing polymeric binder material (i.e. Water based air
drying binder) based on LOFA was synthesized. I mole of fatty acid (LOFA) was
reacted with 0.5 to I mole of epoxy resin with epoxy equivalent weight of about
450 in presence of catalyst such as p-TSA at temperature about 140°C, The
reaction was monitored by FTIR. The synthesized resin is reacted with amine
20 DEA, in mole ratio (0.5 to 1 mole) at temperature 65*2"C for 1 hour. Further the
reaction product was neutralized essentially with phosphoric acid solution by
steering at high speed from 4 to 6 hours Further drier blend of lead (0.05 to 0.5 %
of metal), cobalt (0.005 to 0.05 % of metal) in the ratio 10: 1 (Lead: cobalt) was
added to resin and mixed for about Ihour. The viscosity, NVM of resin was
25 adjusted by using water. The synthesized resin was evaluated for its performance
by applying on a burnished mild steel panel by brush to obtain a dry film
thickness of =loop, coated mild steel specimen were tested for adhesion strength
and corrosion resistance properties.

We Claim:
1. A Water based air drying binder comprising:
vi) Epoxy resin having an epoxy equivalent weight in the range
of 190 to 700;
vii) Fatty acid capable of undergoing oxidative polymerization
without need of any external catalyst or curing agent;
viii) Phosphoric acid for neutralization;
ix) Drier blend of lead and cobalt in the ratio 10: 1 ;
10 x) Water for dilution.
2. A water based air drying binder as claimed in claim 1, wherein the Epoxy
resin is selected from the group consisting of aliphatic or aromatic epoxy
resin.
15
3. A water based air drying binder as claimed in claim 1, wherein the fatty
acid is selected from the group consisting of Linseed oil fatty acid
(LOFA), Tung oil fatty acid (TOFA), Dehydrated Castrol oil fatty acid
(DCOFA), Soya oil fatty acid (SOFA).
20
4. A water based air drying binder as claimed in claim 3, wherein the fatty
acid is preferably Tung oil fatty acid (TOFA).
5. A process for the preparation of water based air drying binder comprising
25 the steps of:
i) Reacting epoxy resin having an epoxy equivalent weight in the
range 190 to 700 with fatty acid in presence of a catalyst at
temperature 60°C to 1 40°C to obtain a synthesized resin;
3 0 ii) Reacting synthesized resin obtained in the step (i) with amine in
mole ratio 0.5 to 1 mole at temperature between 45°C to 105OC,
more preferably at temperature between 65°C to 85°C for 20
minutes to 100 minutes;
iii) Neutralizing the reaction product obtained in step (ii) essentially
with phosphoric acid;
iv) Adding drier blend of lead (0.05 to 0.5% of metal) and cobalt
(0.005 to 0.05 % of metal) in the ratio 10:l (Lead: Cobalt) to the
reaction product obtained in step (iii) and mixing for 1 hour to 3
hours;
v) Diluting the reaction product obtained in step (iv) with water to
obtain water based air drying binder.
10 6. A process for the preparation of water based air drying binder as claimed
in claim 5, wherein the epoxy resin used in step (i) is aliphatic or aromatic
epoxy resin.
7. A process for the preparation of water based air drying binder as claimed
15 in claim 5, wherein fatty acid used in step (i) is selected from the group
consisting of Linseed oil fatty acid (LOFA), Tung oil fatty acid (TOFA),
Dehydrated Castrol oil fatty acid (DCOFA), Soya oil fatty acid (SOFA).
8. A process for the preparation of water based air drying binder as claimed
20 in claim 7, wherein fatty acid used in step (i) is preferably Tung oil fatty
acid (TOFA).
9. A process for the preparation of water based air drying binder as claimed
in claim 5, wherein catalyst used in step (i) is selected from the group
25 consisting of p-toluene Sulphonic Acid (p-TSA) and tri phenyl phosphine.
Dated this the 26th day of March 201 4