FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
Poly(alkyl ricinoleate-co-alkylmaleimide) as pour point depressant for oils
APPLICANT(S):
Crompton Greaves Limited, CG House, Dr. Annie Besant Road, Worli, Mumbai -400030, Maharashtra, India, an Indian Company
INVENTOR
Chaudhari Sushil Ekanath of Crompton Greaves Ltd, Conition Monitoring & Diagnostic Research Centre, CG Global R&D Centre, Kanjur (E), Mumbai 400042, Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of this invention and the manner in which it is to be performed.

TECHNICAL FIELD:
The present invention relates to pour point depressants, poly(aIkyl ricinoleate-co-alkylmaleimide) having formula (I):

Formula (I) Poly(alkylricinoleate-co-alkylmaleimide)
wherein "R" represents C10 to C22 straight chain aliphatic alky] group; "X" represents number of
"-CH2-" units and "n" represents number of operating units
having pour point depressant activity in oil and process for the preparation thereof.
BACKGROUND AND PRIOR ART
The paraffin/wax of the oil starts to crystallize in the form of thin plates, needles or mal-crystals in cold condition. At low temperatures, the plate shaped wax ci-ystals coil on their edges forming needle shaped wax crystals which compact into a 3-dimensional network to form cage like structures. Thus, in cold conditions, when the paraffin from the oil precipitates out, it gets deposited on the wall of the transformer and causes operational problems in the transformers. The storage of oil is also adversely affected in cold conditions due to wax crystals formation.

In their natural state, vegetable oils have high viscosity which causes operational problems in transformers. Hence, all vegetable oils are trans-esterified prior to use as insulating fluids which also increases the cost.
In transformers the oil provides two major functions; the first is as an insulator and the second is as a heat transfer medium to carry heat from the coils to the cooling surfaces of the transformer. These oils must be low in corrosive agents such as acid, alkali and sulfur and resistant to oxidation and sludge formation. In addition to possessing relatively low viscosity, high electric strength and a relatively high flash point, these oils are further characterized in that they must have a relatively low pour point. This is particularly necessary when the oils are used in transformers in colder climates.
A number of compounds are known to improve the low temperature viscometrics of vegetable oils. These compounds are known as "pour point depressants" (PPD's). Pour point depressants are designed to control wax crystal formation in crude oil resulting in improved flow performance of the vegetable oil at lower temperatures, i.e., the PPDs lower the pour point of the vegetable oil. Pour point depressants, when added to crude oil, hindering further growth in that direction and thus preventing wax crystallization and deposition. This reduces the pour point of the oil.
Known PPD's for triglycerides include, but are limited to modified carboxy containing interpolymers; acrylate polymers; nitrogen containing acrylate polymers; and, methylene linked aromatic compounds. Specific examples of pour point depressants used are Ethylene Vinyl Acetate (EVA) copolymers, polymethacrylates, polyacrylates, alkyl esters of styrene-maleic anhydride copolymers, copolymers of olefins, acrylamides, polyacrylamides, copolymers of maleimide, maleic anhydrides, compounds of alkyl amines, alkyl ammonium salts, copolymers of mono, dicarboxylic acids with mono, dipolyhydric alcohols, branched polyalkyl methacrylates with nitrogen containing functional group, sulfone copolymers, copolymers of alpha olefins and maleic anhydride etc.
Many of these pour point depressants like polymethacrylates. polyacrylates and polyalkyl methacrylates are known to be expensive.

Cheaper and effective pour point depressant made from vegetable resources, which would meet the applicable specifications and not compromise the overall biodegradability of industrial fluids, are sorely needed.
OBJECTS OF THE INVENTION:
An object of the invention is to provide pour point depressants for oil.
Another object of the invention is to provide pour point depressants for oil, which are economical.
Another object of the invention is to provide a process for the preparation of pour point depressants, which is simple, easy and convenient to carry out and economical.
DETAILED DESCRIPTION:
According to one of the embodiment of the invention, there is provided poly(alkyl ricinoleate-co-alkylmaleimide) having general formula (I):

Formula (I) Poly(alkyl ricinoleate-co-alkylmaleimide) wherein "R" represents C10 to C22 straight chain aliphatic alkyl group; "X" represents number of "-CH2-"units and "n" represents number of operating units

having pour point depressant activity in oil.
Particularly, poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I) are as follows: 1. Poly(dodecyl ricinoleate-co-alkylmaleimide) of the formula (II):

Formula (II) wherein "X" represents number of "-CH2-" units and "n" represents number of operating units;
2. Poly(decyl ricinoleate-co-alkylmaleimide) of the formula (III):


Formula (III) wherein "X" represents number of "-CH2-" units and "n" represents number of operating units;
3. Poly(tetradecyl ricinoleate-co-alkylmaleimide) of the formula (IV);

Formula (IV) wherein "X" represents number of "-CH2-" units and "n" represents number of operating units;

4. Poly(hexadecyl ricinoleate-co-alkylmaleimide) of the formula (V):

Formula (V) wherein "X" represents number of "-CH2-" units and "n" represents number of operating units;
5. Poly(octadecyl ricinoleate-co-alkylmaleimide) of the formula (VI);

Formula (VI) wherein "X" represents number of "-CH2-" units and "n" represents number of operating units;

and 6. PoIy(behenyl ricinoleate-co-alkylmaleimide) of the formula (VII):

Formula (VII)
wherein "X" represents number of "-CH2-" units and "n" represents number of operating units.
More particularly, poIy(alkyl ricinoleate-co-alkylmaleimide) of formula (I) are as follows: 1. Poly(dodecyl ricinoleate-co-decylmaleimide) of the formula (VIII):


Formula (VIII) wherein "n" represents number of operating units;
2. Poly(decyl ricinoleate-co-decylmaleimide) of the formula (IX):

Formula (IX) wherein "n" represents number of operating units;
3. Poly(tetradecyl ricinoleate-co-decylmaleimide) of the formula (X):


Formula (X) wherein "n" represents number of operating units;
4. PoIy(hexadecyl ricinoleate-co-decylmaleimide) of the formula (XI);

Formula (XI) wherein "n" represents number of operating units;
5. PoIy(octadecyl ricinoleate-co- decylmaleimide) of the formula (XII):


Formula (XII) wherein "n" represents number of operating units;
and 6. Poly(behenyl ricinoleate-co-decylmaleimide) of the formula (XIII):

Formula (XIII) wherein "n" represents number of operating units.

According to the invention, there is also provided process for the preparation of poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I):

Formula (I)
Poly(alkylricinoleate-co-alkylmaleimide) wherein "R" represents C10 to C22 straight chain aliphatic alkyl group; "X" represents number of
"-CH2-" units and "n" represents number of operating units
having pour point depressant activity in oil;
the process comprising:
a. esterifying unsaturated ricinoleic acid with C10 to C22 aliphatic alcohol in the molar ratio
of 1.5:1 to 2:1 in the presence of acid catalyst under Eizeotropic conditions to obtain an
alkyl ester of ricinoleic acid;
b. copolymerizing the alkyl ester of ricinoleic acid with a double re-crystallized maleic
anhydride in the 1:1 molar ratio under inert atmosphere and in the presence of an organic
solvent and a free radical initiator at 50°C to 75°C to obtain a poly(alkyl ricinoleate -co-
maleic anhydride) copolymer; and
c. condensing the copolymer with amine in the presence of activated 4° A molecular sieves
at 90°C to 150°C to obtain the poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I).
The C10 to C22 aliphatic alcohol is selected from decyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, octadecyl alcohol, behenyl alcohol, etc.

Preferably, the organic solvent is selected from toluene, dry benzene, methanol, or xylene, etc. The inert atmosphere is provided by dry nitrogen gas. Preferably, the free radical initiator is benzoyl peroxide or azobisisobutyronitrile (AIBN). The acid catalyst is para-toluene sulfonic acid or sulphuric acid or combination thereof.
The amine used is decylamine, dodecylamine, tetradecylamine, hexadecyl amine, octadecyl amine, behenyl amine etc.
The invention also provides oil comprising poly(alkyl ricinoleate -co-alkylmaleimide) of formula (I) having pour point depressant activity in the oil.
The oil comprises 100 to 3000 ppm of poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I) to improve the pour point of oil.
The oil used is vegetable oil, crude oil or any other oil.
The crude oil comprises 1000 to 3000 ppm of poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I) to improve the pour point of oil.
The vegetable oil comprises 100 to 500 ppm of poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I) to improve the pour point of oil.
Preferably, crude oil comprises 1000 to 3000 ppm of poly (alkyl ricinoleate-co-alkylmaleimide) of formula (I) to improve the pour point of oil which will reduce the pour point of the oil up to maximum -3°C.
Preferably, Indian Beech/Karanj (Millettia pinnata) oil comprises 100 to 500 ppm of poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I) to improve the pour point of oil which will reduce the pour point of the oil up to maximum -6°C

Preferably, Rapeseed oil comprises 100 to 500 ppm of poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I) to improve the pour point of oil which will reduce the pour point of the oil up to maximum-15°C
Poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I) of the invention is very effective and efficient in improving the pour point of oil and is prepared using raw materials like behenyl alcohol, decyl alcohol, dodecyl alcohol and ricinoleic acid which are easily obtainable from the naturally occurring fats and oils, Therefore, the pour point depressant of the invention is economical. The process of the invention is also simple, easy and convenient to carry out and economical.
The following experimental examples are illustrative of the invention but not limitative of the scope thereof:
Example 1:
Excess ricinoleic acid was esterified with C10 , C12 ,C14, C16, C18 and C22 straight chain aliphatic alcohols in a molar ratio of 2:1 at 310° C for 8 to 12 hours in presence of dry toluene as a solvent and 0.2 ml of sulphuric acid as a catalyst to yield six different respective alkyl esters of ricinoleic acid. Water was eliminated by azeotropic distillation. The resulting crude esters were neutralized with sodium bicarbonate. The organic layer was separated and washed with water to remove traces of sodium bicarbonate and finally dried over anhydrous sodium sulphate. Solvent recovery was achieved by vacuum distillation. Table 1.1 illustrates the quantities of reactants used for the preparation of each of these esters.
Table 1.1 Data related to preparation of alkyl ricinoleate

Reactants Toluene ml H2SO4 ml Alkyl ricinoleate
Ricinoleic acid mole Fatty Alcohol mole

0.052 M Decyl alcohol 0.026 M 50 0.2 Decyl ricinoleate
0.052 M Dodecyl alcohol 50 0.2 Dodecyl ricinoleate

0.026 M
0.052 M Tetradecyl alcohol 0.026 M 70 0.2 Tetradecyl ricinoleate
0.052 M Hexadecyl alcohol 0.026 M 70 0.2 Hexadecyl ricinoleate
0.064 M Octadecyl alcohol 0.032 M 80 0.2 Octadecyl ricinoleate
0.040 M Behenyl alcohol 0.020 M 50 0.2 Behenyl Ricinoleate
The alkyl ricinoleic esters (alkyl ricinoleate) of the table 1 were then copolymerized with double recrystallized maleic anhydride in 1:1 molar ratio in the presence of dry benzene under dry nitrogen atmosphere with azobisisobutyronitrile as an initiator at 55° C to 60° C with constant stirring for 8 hours to give poIy(alkyl recinoleate-co-maleic anhydride). The resulting poIy(aIkyI recinoleate-co-maleic anhydride) were purified by repeated solvent non-solvent method (Benzene-methanol). Traces of solvent were removed by drying under reduced pressure at 50°C / 25mm Hg for 5 hours. Table 1.2 illustrates the quantities of the reactants used in the copolymerization reaction.
Tablel.2 Data related to preparation of poly(alkyl ricinoleate-co-maleic anhydride)

Reactants Benzene
ml Copolymer
Alkyl ricinoleate Maleic Azobisisobuty

(mole) anhydride
(mole) -ronitrile gm (% wt. of
total monomers)
Decyl ricinoleate 0.020 M 0.020 M 0.107 gm 50 poly(decyI ricinoleate-co-maleic anhydride)
Dodecyl ricinoleate 0.021 M 0.021 M 0.118gm 50 poly(dodecyl ricinoleate-co-maleic anhydride)

Tetradecyl ricinoleate 0.020 M 0.020 M 0.318gm 50 poly (tetradecyl ricinoleate-co-maleic anhydride)
Hexadecyl ricinoleate 0.019 M 0.019 M 0.117 gm 50 poly(hexadecyl ricinoleate-co-maleic anhydride)
Octadecyl ricinoleate 0.018 M 0.018 M 0.116gm 50 poly(octadecyl ricinoleate-co-maleic anhydride)
Behenyl ricinoleate 0.013 M 0.013 M 0.091 gm 20 poly(behenyl ricinoleate-co-maleic anhydride)
The anhydride copolymers were condensed with the decyl amine in a molar ratio of 1:1 in the
presence of 1 gm of activated 4° A molecular sieves at 90°C to 150°C to produce amides;
poly(decyl ricinoleate-co-decylmaleimide); poly(dodecyl ricinoleate-co-decyl maleimide);
poly(tetradecyl ricinoleate-co-decyl maleimide); poly(hexadecyl ricinoleate-co-decyl
maleimide); poly(octadecyl ricinoleate-co-decyl maleimide); poly(behenyl ricinoleate-co-decyl maleimide).
Table 1.3 illustrates the quantities of the reactants used in the condensation reaction.
Table 13 Data related to preparation of poly(alkyl recinoltfate-co-decylmaleimide)

Reactants Solvent (ml) Pour Point Depressants
Copolymer
(mole) Decyl amine
(mole) Activated 4° A
molecular
sieves

Poly(decyl ricinoleate-co-
maleic anhydride)
0.013 M 0.013 M 1 gm 40 PoIy(decyl ricinoleate-co-decylmaleimide)
Poly(dodecyl ricinoleate-
co-maleic anhydride)
0.011 M 0.011 M 1 gm 40 Poly(dodecyl ricinoleate-co-decyl maleimide)
Poly(tetradecyl
ricinoleate-co-maleic
anhydride) 0.011 M lgm 40 Poly(tetradecyl ricinoleate-co-decyl maleimide)

0.011 M
Poly(hexadecyl
ricinoleate-co-maleic
anhydride)
0.012 M 0.012 M 1 gm 40 Poly(hexadecyl ricinoleate-co-decyl maleimide)
Poly(octadecyl
ricinoleate-co-maleic
anhydride)
0.011 M 0.011M 1 gm 40 Poly(octadecyl ricinoleate-co-decyl maleimide)
Poly(behenyl ricinoleate-co-maleic anhydride) 0.0075 M 0.0075 M 1 gm 40 Poly(behenyl ricinoleate-co-decyl maleimide)
Pour Point Depressants (additives) prepared according to table 1.3 of the invention were tested for its pour point depressant activity by standard method as prescribed by the ASTM D97.
1000 ppm, 2000 ppm and 3000 ppm of various pour point depressants of Table 1.3 were added to crude oil and tested for their pour point depressant activity. The results of the pour point of the crude oil on addition of 1000 ppm, 2000 ppm and 3000 ppm of various pour point depressants of the invention were shown in the Table 1.4.
Table 1.4 : Pour point of crude oil after adding varying amount of pour point depressants of the invention in the oil.

our point depressants (PPD) Pour
point of
virgin
crude
oil (°C) J Pour point of crude oil after addition of PPD
(°C) Extent of depression in pour point (°C)

1000
ppmof
PPD 2000
ppm of
PPD 3000
PDm of
PPD 1000 ppm of PPD 2000
ppm of
PPD 3000
ppm of
PPD
Poly(decyl recinoelate-co-
decylmaleimide) [Alkyl chain length=C]o] 39 20 20 12 19 19 27
Poly(dodecyl recinoelate-
co-decylmaleimide) [Alkyl chain lengtlr=C12] 39 21 18 9 18 21 30

Poly(tetradecyl
recinoelate-co-decylmaleimide) 39 18 18 15 21 21 24
[Alkyl chain length=C14]
Poly(hexadecyl
recinoelate-co-decylmaleimide) 39 12 12 7 27 27 32
[Alkyl chain length=C16]
Poly(octadecyl
recinoelate-co-decylmaleimide) 39 10 7 5 29 32 34
[Alkyl chain length=C18]
Poly(behenyl recinoelate-
co-decylmaleimide) 39 10 5 -3 29 34 42
[Alkyl chain length=C22]
According to the results of Table 1.4, the pour point depressants of the invention namely; poly(decyl ricinoleate-co-decylmaleimide), poly(dodecyl ricinoleate-co-decyl maleimide), poly(tetradecyl ricinoleate-co-decyl maleimide); poly(hexadecyl ricinoleate-co-decyl maleimide), poly(octadecyl ricinoleate-co-decyl maleimide) and poly(behenyl ricinoleate-co-decyl maleimide) has excellent pour point depressant activity in crude oil in a of concentrations of 1000 ppm to 3000 ppm which will reduce the pour point up to maximum -3°C as shown in the above table 1.4.
100 ppm and 500 ppm of various pour point depressants of Table 1.3 were added to Indian Beech/ Karanj (Millettia pinnata) and tested for their pour point depressant activity. The results of the pour point of the Indian Beech/ Karanj {Millettia pinnata) on addition of 100 ppm and 500 ppm of various pour point depressants of the invention were shown in the Table 1.5.

Table 1.5 : Pour point of Indian BeechlKaranj (Mitlettia pinnata) after adding varying amount of pour point depressants of the invention in the oil.
Pour point depressant (PPD) Pour point of Indian Beech/ Karanj
(°C) Pour point of Indian BeechlKaranj after addition ofPPD (°C) Extent of depression in pour point (°C)

100 ppm ofPPD 500 ppm ofPPD 100 ppm ofPPD 500 ppm of PPD
Poly(decyl recinoelate-co-
decylmaleimide) [Alkyl chain length=C10] 21 15 12 6 9
Poly(dodecyl recinoelate-co-
deecylmaleimide)
[Alkyl chain lengthen] 21 15 12 6 9
Poly(tetradecyl recinoelate-co-
decylmaleimide)
[Alkyl chain length=C14] 21 15 11 6 10
Poly(hexadecyl recinoelate-co-
decylmaleimide)
[Alkyl chain length=C16] 21 9 6 12 15
Poly(octadecyl recinoelate-co-
decylmaleimide)
[Alkyl chain length=C18] 21 3 *> 18 24
Poly(behenyl recinoelate-co-
decylmaleimide)
[Alkyl chain Iength=C22] 21 1 -6 20 27
According to the results of Table 1.5, the pour point depressants of the invention namely; poly(decyl ricinoleate-co-decylmaleimide)? po!y(dodecyl ricinoleate-co-decyl maleimide), poly(tetradecyl ricinoleate-co-decyl maleimide); poly(hexadecyl ricinoleate-co-decyl maleimide), poly(octadecyl ricinoleate-co-decyl maleimide) and poly(behenyl ricinoleate-co-decyl maleimide) has excellent pour point depressant activity in Indian Beech/ Karanj {Millettia

pinnata) oil in range of concentration from 100 ppm (o 500 ppm which will reduce the pour point up to maximum -6°C as shown in the above table 1.5.
100 ppm and 500 ppm of various pour point depressants of Table 1.3 were added to Rapeseed oil and tested for their pour point depressant activity. The results of the pour point of the Rapeseed oil on addition of 100 ppm, and 500 ppm of various pour point depressants of the invention were shown in the Table 1.6.
Table 1.6 : Pour point of Rapeseed oil after adding varying amount of pour point depressants of the invention in the oil.

Extent of
Pour Point Depressant Pour point of PPD treated depression in pour point
Pour point of Rapeseed oil (°C) Rapeseed oil (°C) (°C)

100 500 100 500
ppm of ppm of ppm of ppm of
PPD PPD PPD PPD
Poly(decyl recinoelate-co-
decylmaleimide) 7 1 -3 6 10
[Alkyl chain length=C10]
Poly(dodecyl recinoelate-co-
decylmaleimide) 7 1 -3 6 10
[Alkyl chain length=C12]
Poly(tetradecyl recinoelate-co-
decylmaleimide) 7 -3 -6 10 13
[Alkyl chain length=C14]
Poly(hexadecyl recinoelate-co-
decylmaleimide) 7 -6 -12 13 19
[Alkyl chain length=C16]

Poly(octadecyl recinoelate-co-
decylmaleimide) 7 -6 -12 13 19
[Alkyl chain length= C18]
Poly(behenyl recinoelate-co-
decylmaleimide) 7 -12 -15 19 21
[Alkyl chain length= C22]
According to the results of Table 1.6, the pour point depressants of the invention namely; poly(decyl ricinoleate-co-decylmaleimide), poly(dodecyl ricinoleate-co-decyl maleimide), poly(tetradecyl ricinoleate-co-decyl maleimide), poly(hexadecyl ricinoleate-co-decyl maleimide), poly(octadecyI ricinoleate-co-decyl maleimide) and poly(behenyl ricinoleate-co-decyl maleimide) has excellent pour point depressant activity in Rapeseed oil in range of concentration from 100 ppm to 500 ppm which will reduce the pour point up to maximum -15°C as shown in the above table 1.6.
The present invention as described above, it is to be understood that this invention is not limited to particular methodologies and materials described, as these may vary as per the person skilled in the art. It is also to be understood that the terminology used in the description is for the purpose of describing the particular embodiments only, and is not intended to limit the scope of the present invention.

WE CLAIM:
I. A poIy(alkyl ricinoleate-co-alkylmaleimide) having general formula (I):

Formula (I)
wherein "R" represents Cio to C22 straight chain aliphatic alkyl group; "X" represents number of "-CH2-" units and "n" represents number of operating units having pour point depressant activity in oil.
2. The poly(alkyl ricinoleate-co-alkylmaleimide) having general formula (I) as claimed in claim 1, which is poly(dodecyl ricinoleate-co-alkylmaleimide) of the formula (II):


wherein "X" represents number of "-CH2-" units and "n" represents number of operating units.
3. The poly(a]kyJ ricifloleate-co-alkylmaleimide) having genera] formula (J) as claimed in claim 1, which is poly(decyl ricinoleate-co-alkylmaleimide) of the formula (III):

Formula (III) wherein "X" represents number of "-CH2-" units and "n" represents number of operating units.
4. The poly(alkyl ricinoieate-co-alkylmaleimide) having general formula (I) as claimed in
claim 1, which is poly(tetradecyl ricinoleate-co-alkylmaleimide) of the formula (IV):


Formula (IV)
wherein "X" represents number of "-CH2-" units and "n" represents number of operating units.
5. The poIy(a!ky! ricinoleate-co-alkylmaleimide) having general formula (I) as claimed in claim 1, which is poly(hexadecyl ricinoleate-co-alkylmaleimide) of the formula (V):

Formula (V) wherein "X" represents number of "-CH2-" units and "n" represents number of operating units.

6. The poly(alkyl ricinoleate-co-alkylmaleimide) having general formula (I) as claimed in claim 1, which is poly(octadecyl ricinoleate-co-alkylmaleimide) of the formula (VI);

Formula (VI) wherein "X" represents number of "-CH2-" units and "n" represents number of operating units.
7. The poly(alkyl ricinoleate-co-alkylmaleimide) having general formula (I) as claimed in claim 1, which is poly(behenyl ricinoleate-co-alkylmaleimide) of the formula (VII):


wherein "X" represents number of "-CH2-" units and "n" represents number of operating units.
8. A process for the preparation of poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I):

Formula (I) poly(alkylricinoleate-co-alkylmaleimide) wherein "R" represents C10 to C22 straight chain aliphatic alkyl group; "X" represents number of "-CH2-" units and "n" represents number of operating units having pour point depressant activity in oil; the process comprising:
a. esterifying unsaturated ricinoleic acid with C10 to C22aliphatic alcohol in the molar
ratio of 1.5:1 to 2:1 in the presence of acid catalyst under azeotropic conditions to
obtain an alkyl ester of ricinoleic acid;
b. copolymerizing the alkyl ester of ricinoleic acid with a double re-crystallized maleic
anhydride in the 1:1 molar ratio under inert atmosphere and in the presence of an
organic solvent and a free radical initiator at 50°C to 75°C to obtain a poly(alkyl
ricinoleate -co-maleic anhydride) copolymer; and
c. condensing the copolymer with amine in the presence of activated 4° A molecular
sieves at 90°C to 150°C to obtain poly(alkyl ricinoleate-co-alkylmaleimide) of formula (I).

9. The process as claimed in claim 8, wherein the C10 to C22 aliphatic alcohol is selected from behenyl alcohol, decyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, octadecyl alcohol or behenyl alcohol.
10. The process as claimed in claim 8, wherein the organic solvent used in step (b) is selected from toluene, dry benzene, methanol, or xylene.
11. The process as claimed in claim 8, wherein the amine used in step (c) is decylamine, dodecylamine, tetradecylamine, hexadecyl amine, octadecyl amine or behenyl amine.
12. A crude oil comprising poly(alkyl ricinoleate-co-alkylmaleimide) having general formula (I) in range of concentration from 1000 ppm to 3000 ppm has excellent pour point depressant activity which will reduce the pour point of the oil up to maximum -3°C.
13. Indian Beech/ Karanj (Millettia pinnata) oil comprising poly(a!kyl ricinoleate-co-alkylmaleimide) having general formula (I) in range of concentration from 100 ppm to 500 ppm has excellent pour point depressant activity which will reduce the pour point of the oil up to maximum -6°C.
14. Rapeseed oil comprising po\y(alkyl ricinoleate-co-alkylmaleimide) having general formula (I) in range of concentration from 100 ppm to 500 ppm has excellent pour point depressant activity which will reduce the pour point of the oil up to maximum -15°C.