FORM-2
THE PATENTS ACT, 1970
COMPLETE SPECIFICATION
(SECTION -10)
A NEW INSULATING FLUID BASED ON A NATURAL
ESTER
SAVITA OIL TECHNOLOGIES LIMITED, a company registered in India having its registered office at 66/67, Nariman Bhavan, Nariman Point, Mumbai - 400 021. (India)
An Indian Company
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention deals with the use of a new insulation fluid based on Mustard Oil (a natural ester). The new composition comprises a mixture of chemically modified Mustard Oil and alkyl esters of chemically modified mustard oil fatty acids. The said composition may be used in transformers (distribution or power), Switch gear, Capacitors or electrical cables. The invention also provides a process for making the new insulating fluids.
PRIOR RELATED ART
Mineral Oils are being used as insulating fluids for more than a century. An insulating fluid in a transformer has two main functions. First, it dissipates heat generated during operation and acts as a coolant. Secondly, it provides dielectric properties to the transformer. In addition, it also has to be compatible with the material of construction of transformers. It also has high dielectric strength and low dielectric dissipation factor which are key requirements for insulation effectiveness.
Although mineral oil satisfies functional requirements reasonably well, they lack the following important features, viz.
1. They can't be classified as non-flammable, having a low flash point of 140°C

2. They are not environmentally friendly as they are classified as non-biodegradable
In 1930's a fluid known as askarel (PCB, Polychlorinated biphenyl) partly substituted mineral oils wherever non-flammability was an issue. However, PCB's were eventually banned world-wide due to carcinogenicity. PCB's are also nonbiodegradable.
The transformer industry has always been looking for fluids which are functionally good and at the same time usable in environmentally sensitive areas like forests or marine environment. The industry has also been seeking the development of nonflammable fluids with high flash point and fire point so that they may be used in areas close to high-rise buildings, shopping malls etc.
Prior art is described in a set of patents publication (U.S. Pat. No.6,037,537 filed Mar. 14, 2000, U.S. Pat. No.6,184,459 Bl filed Feb. 6, 2001, U.S. Pat. No.6,352,655 Bl filed Mar. 5, 2002, U.S. Pat No.6,613,250 B2 filed Sep. 2, 2003, U.S. Pat. No.6,398,986 Bl filed Jun. 4, 2002, U.S. Pat. No.6,6905,638 B2 filed Jun. 14, 2005 assigned to Cooper industries),which attempts to take care of the above concerns. These patents do talk about the use of food grade vegetable oils which include castor, coconut, corn, cottonseed, crambie, jojoba, lesquerella, linseed, olive, palm,

rapeseed (canola), safflower, sunflower, soya, and veronia or their blends. These oils are claimed to be good insulating fluids finding applications in distribution and power transformers.
However, these compositions are based on blends of vegetable oils mentioned above. The most important difference in comparison to our present invention is that the above mentioned vegetable oils are not based on Mustard Oil. The patent applications do not explicitly mention this vegetable oil. Our invention is based on Mustard oil and modifications thereof. Secondly, Chemical modification is not part of Cooper industry's patents whereas Chemical treatment is an essential feature of our invention. This modification confers improved oxidation stability to our oils in comparison as exemplified in fig. 1. Yet another important difference between the two inventions is that in the above referred patents, pure vegetable oils are used. Whereas, in our invention the product that is used is necessarily a blend of mustard oil and a specifically chosen alkyl ester, namely alkyl ester of CMO (chemically Modified Mustard Oil) fatty acids. The second component can be varied from 5% to 20 % in the formulation. The second component is as important as the first component CMO in conferring functional properties (to the insulating fluid) as well as acting as a thinner. It also works to improve low temperature properties of the fluid,
We also take reference to another U.S. Pat.7,048,875 B2 filed May. 23, 2006 assigned to ABB. This patent describes the invention of

BIOTEMP which is based on Sunflower oil which is genetically modified or specially breeded to make high-oleic vegetable oils suitable for insulating applications. This also differs significantly from our invention in two respects: Firstly our invention is based on Mustard Oil whereas ABB's invention is based on Sunflower Oil. Secondly our product is based on Chemical Modification unlike Biotenip which is a natural ester from genetically modified or specially breeded seeds. Similarly an Australian Patent assigned to Wray & Associates (Pub. No. WO/2007/041,785) also describes tlie use of a product which is based on genetically modified vegetable oils (mustard oil is NOT part of the description) to produce high oleic oils as insulating fluids. This also differs from our present invention for the reason that our application is based on Mustard oils and modifications thereof.
There is one more patent publication assigned to Wavely Light & Power (U.S. Pat.6,340,658 filed 2002, U.S. Pat.5,958,851 filed Nov. 5, 1998), which describes the use of selectively hydrogenated soyaoil subjected to winterization and blended with methyl esters of soya fatty acids as thinners. Our Invention differs significantly from this patent also in several respects. Firstly b)T using mustard oil, the costly winterization step is completely eliminated. The oil chosen by us is rich in Monounsaturated Fatty Acid (Erucic acid about 46% to 50%, Oleic acid 9% to 12%) and poor in Saturated fatty acid (About 3% to 5%). The latter is present in soya in substantial quantities and contributes to wax content, necessitating the costly winterization step.

Secondly, the patent above uses methyl esters of soya fatty acids as the thinners up to a concentration of 20%. Methyl esters can potentially cause deterioration of rubber seals used in a transformer. Our invention uses a long chain ester of mustard oil fatty acids. This innovative approach at once solves two issues: 1. No adverse interaction with seals in a transformer. 2. It can provide some improvement in pour point. (Table- 1 shows a comparison of pour points with metlryl ester versus long chain alkyl ester as the blend component).3. Thirdly, use of methyl esters (ME) even @ 5% level would significantly reduce flash & fire points (see table- 2)
Thus our invention is different from all the patents referred to above and provides a unique composition which confers technically unique benefits outlined above.
SUMMARY OF THE INVENTION
The present invention is related to a novel application of Mustard Oil based fluids as insulating liquids in transformers, Switch gears, Capacitors and electrical cables. In one aspect, the invention deals with a process for chemical modification of the RBD (refined, bleached & deodourized) mustard oil, which consists of selective hydrogenation of the oil using selective nickel and/or platinum catalysts. The selective hydrogenation makes the oil suitable for further formulation. The compositions have 3 components.

Another aspect of the current invention is the environmental friendliness of the new fluids. The finished fluids of the invention are Fully biodegradable as per OECD 301C AND 301F.
The fiTst Compomnt is a comically modified Mustard oiV
The second component to be blended into the fluid of the invention may be selected from C7 to CIO alcohols which are esterified with CMMFA (Chemically modified Mustard oil fatty acids). The second component of the blend may be conveniently described as alkyl esters of fatty acids (AFA) and a detailed significance of this component will be described in more detail later in the specification. The second component of the blend may be incorporated preferably from 0 to 30% and in some embodiments from 10% to 30% or most preferably from 10% to 15%.
The invention further incorporates a third component consisting of additives. The additives in the formulation improve low temperature properties and oxidation stability of the fluids. The additives may be chosen from the class of antioxidants as well as metal passivators and pour point depressants. The latter are sometimes added to protect the transformer fluid from catalytic oxidation by passivating copper metal which is part of a transformer construction. In another embodiment of the invention the blended components are purified to remove acidic polar impurities and this purification is carried out before adding the additives.

DETAILED DESCRIPTION OF THE INVENTION
This invention deals with the novel application of vegetable oils such as Mustard Oil and their derivatives as dielectric fluids. The dielectric fluids (also referred to as insulation fluids) may be used in transformers, capacitors and switch gears, electrical cables etc.
Traditionally mineral oil based formulations are used for such applications. However, these have certain limitations for applications requiring environmental friendliness and high fire safety. This invention fulfils the need for such a requirement in the industry. The fluids pass the OECD 301C &301F test for biodegradability and may be classified as fully biodegradable.
The invention uses RBD (refined, bleached & deodorized) mustard oil as the source of raw material. RBD mustard oils are well known in the commerce and are readily available. The technologies for RBD are well known and they are readily supplied by several vendors. The main aspect of the invention concerns chemical modification of RBD oils to produce Oleic and erucic acid rich vegetable oils (rich in mono-unsaturated fatty acids). The basic invention involves the use of 3 components, which are described below:

FIRST COMPONENT
The preferred practice of the invention uses CMO (chemically Modified Mustard Oil) to achieve certain targeted fatty acid compositions and better low temperature properties.
In one preferred practice of the invention, the blended first component contains mono-unsaturated fatty acid between 55% to 75%, diunsaturated fatty acid is kept between 12% to 17% and tri-unsaturation is kept low between 1% to 4%.
In another more preferred practice, mono-unsaturated fatty acid is kept in the range of 60% to 70%, diunsaturated fatty acid is in the range of 12% to 15% and triunsaturated fatty acid is present as low as possible.
This modification of RBD oil is carried out using commercially available Selective supported Nickel catalyst or platinum catalysts. The conditions of hydrogenation are varied to achieve the above selective compositions.
The above preferred chemical compositions are based on the premise that mono-unsaturated fatty acids confer the best oxidative stability. Although fully saturated fatty acids are known to give even better stability, they are not preferred due to poor low temperature properties. Therefore the idea is to get minimum

saturated fatty acids, and minimize the diunsaturated and triunsaturated fatty acids and maximize mono-unsaturation.
SECOND COMPONENT
The second major aspect of the invention is the use of second component to the first component. The second component consists of alkyl esters of fatty acids in the formulation of the insulation fluids to control viscosity. In choosing this component, we took care to minimize adverse effects on lowering of flash & fire points and also possible effects on transformer seal materials.
Accordingly, in one preferred method, the alkyl ester of fatty acid with heptanol or octanol were chosen. In another preferred method, the alkyl ester of fatty acids with isooctanol or decanol were chosen. In yet another preferred embodiment the alkyl ester is chosen from heptyl, octyl, isooctyl and decyl alcohols or mixtures thereof.
Esterification to prepare the above esters may be carried out by conventional methods using PTSA, and/or Tin based heterogeneous or homogeneous catalysts.
The esters above may also be. prepared by transesterification methods by reacting the alcohols with the vegetable oil directly, using sodium methoxide as the catalyst.

In one preferred method to prepare the insulating fluids, the second component is blended with the first component in70:30100:0 ratios. In yet another preferred method, the blend ratio was maintained between 90:10 to 80:20. In another most preferred embodiment, the said ratio is maintained between 90:10 to 95:5.
The above blends are further purified to remove polar impurities to improve electrical properties of the insulating fluids.
In one aspect of the purification method, the blends are percolated through granular earth, which is thermally activated. In another aspect of the invention, the oil blends may be percolated through acid activated clays such as Bentonite. In yet another preferred embodiment of the invention, the blends are purified by passing through activated Alumina adsorbents which are commercially available. Optionally the blends may be vacuum filtered.
The resulting product will have water content (IEC 60814) varying from lOOppm to 500ppm and neutralization value (IEC 62021) in the range from 0.03 to 0.05, depending upon the nature of treatment.
The base fluid has Break Down Voltage in the range of 70 kV to 75 kV (in 2.4 mm gap). Dielectric Dissipation Factor @ 90°C is in the range of 2% to 3%.

THIRD COMPONENT
Most of all vegetable oils contain primarily unsaturated fatty acids (mono-, di-, tri-unsatu rated fatty acids). Due to presence of these fatty acids they are more susceptible to oxidation upon exposure to free oxygen in presence of metal catalyst like copper. The oxidation process of these oils leads to formation <•!' the polymerization products. These polymerization products tend to show marked increase in viscosity and the oils correspondingly show decrease in insulating properties. These products also reduce the efficiency of dissipating the heat generated during the usage of transformers. The degree of polymerization is proportional to the temperature as well as the extent of exposure of oil to the oxygen.
The insulating fluids in the current inventions may comprise one or more oxidation inhibiting components. These are primarily potent components responsible for reduction of concentration of free oxygen in free area surrounding the dielectric fluid as well as the dissolved oxygen in the fluid inside the sealed electrical distribution equipment.
The oil blends prepared above are therefore optionally subjected to further formulations by addition of one or more antioxidants additives. The blended oils may be fortified with antioxidant additives to improve oxidation stability of the fluids. The additives may be chosen from Phenolic and/or aminic antioxidants. They mav be used alone or in combination % by weight from 0.1 to 1.2

%. They are chosen from the following commercially available products:
IRGANOX1010, IRGANOXL06, IRGALUBE 349, IRGALUBE TPPT, and alpha-, beta- or delta-tocopherol (Vitamin E).
DPA (Diphenyl amine), BHT (Butylated hydrotoluene),TBHQ (Mono tertiary butyl hydroquinone), BHA (Butylated hydroxyanisole), ascorbyl palmitate (rosemary oil), Propyl gallate
etc.
The oxidation stability is tested as per IEC 61125 METHOD C.
Oxidation stability is also measured by determining the variation of viscosity with time: Please see drawings. The drawing (fig. - 1) shows the importance of chemical modification. The samples which are NOT chemically modified (made as per patents assigned to COOPER POWER SYSTEMS) showed a big increase in viscosity while the chemically modified fluid as per the present invention shows relatively less increase in viscosity with time of oxidation. (Higher the viscosity, lower the cooling efficiency of the fluid).
Table- 2 highlights the significance of use of higher alcohol based fatty acid esters for imparting higher flash & fire points. Use of methyl esters as a thinning agent suggested by patents publication assigned to Wavely Light & Power (U.S. Pat.6,340,658 filed 2002, U.S. Pat.5,958,851 filed Nov. 5, 1998), show a big drop in flash & fire point in comparison to the values obtained from our invention also they shows adverse effects on seals. Fluids of our invention

show values of flash point and fire point much better than ASTM standard specifications (ASTM D6871 -03). One corolary of the Table 2 is that in the practice of this invention one can optionally use CMMO without any second component to achieve a very high flash point of 320degC and fire point of 340degC. In this case, however, the viscosity of the fluid will also be at 51 est @ 40degC.
The performance of dielectric fluids in extreme cold conditions is important. The established mineral oils which are used as insulating fluids have considerably lower pour points and also have better cold flow properties than vegetable oils. A typical insulating fluid needs pour point below -20°C. The insulating fluids in current inventions alone were insufficient by themselves for lowering pour point. Hence pour point depressants improve the operational range of insulating fluids.
In our current invention the pour points or the cold flow property is partially improved b}^ blending with the alkyl esters of the CMO (chemically modified mustard oil fatty acids).
In one aspect of the formulation, pour point depressants (PPD) may be added further to improve low temperature properties. These may be chosen from polymethacrylates or polyolefins based compounds. The blended oils may be fortified with pour point depressants to improve pour points of the fluids. They may be used alone or in combination. They are chosen from the following commercially available products: Evonik (1-300), Infineum

(V388), lubrizol (LZ7745 and LZ966), Rohm GmbH (Viscoplex 1-330)
The addition levels may van- from 0.1 to 1.8 %. The resulting fluid will have pour points varying from -15°C to -18°C
Typically, the finished formulation will have Water Content (IEC 60814): lOOppm to 175ppm. Neutralization Value (IEC 68021): 0.030 to 038, Flash Point (ASTM D98) :290°C to 895°C, Fire Point (ASTM D92) :320°C to 325°C. Pour Point (ISO 3016): -18°C to -21°C, Viscosity (ISO 3014) @ 40°C :40 cSt to 46 cSt, Viscosity (ISO 3014)@ 100°C :9.5 cSt to 11 cSt, Break Down Voltage: 70kV to 75kV, Dielectric Dissipation Factor (IEC 60847) @90°C: 2% to 3%.
THE FOLLOWING EXAMPLES ILLUSTRATE THE PRACTICE OF THE INVENTION
Example 1: (for component one) Chemically modified mustard oil (CMO) is prepared by hydrogenating the refined mustard oil by using nickel catalyst under hydrogen pressure of 6kg/cm2 and temperature of 130°C to get monounsaturated fatty acids in range of 58% and triunsturated fatty acid content below 3.5%.
Example 2: (for component two) Fatty acids of chemically modified mustard oil (CMMOFA) are prepared by splitting the chemically modified mustard oil by using sodium hydroxide and

later by concentrated sulphuric acid by well known methods. Heptyl ester of CMMO (chemically modified mustard fatty acids) is prepared by reacting Heptyl alcohol with CMMOFA by using a catalyst like Fara Toluene sulphonic acid and/or sulphuric acid at a temperature of 180°C.
Example 3: (for component two) Octyl esters of CMMO is prepared by reacting octyl alcohol with CMMOFA by using a catalyst like Fara Toluene sulphonic acid and/or sulphuric acid at a temperature of 180°C.
Example 4: (for component two) Decyl esters of CMMO is prepared by reacting Decyl alcohol with CMMOFA by using a catalyst like Para Toluene sulphonic acid and/or sulphuric acid at a temperature of 180°C.
Example 5: (for component two) Heptyl esters of CMMO is prepared by transesterification of heptyl alcohol with CMMO by using sodium methoxide as a catalyst at a temperature of 110°C.
Example 6: (for component two) Octyl esters of CMMO is prepared by transesterification of octyl alcohol with CMMO by using sodium methoxide as a catalyst at a temperature of 110°C.
Example 7: (for component two) Decyl esters of CMMO is prepared by transesterification of Decyl alcohol with CMMO by using sodium methoxide as a catalyst at a temperature of 110°C.
Example 8: The blends of component one (CMMO from example 1) and component two (from example 2 ) were prepared in the ration varying from 70:30.

Example 9: The blends of component one (CMMO from example 1) and component two (from example 3 ) were prepared in the ratio varying from 90:10.
Example 10: The blends of component one (CMMO from example 1) and component two (from example 4 o) were prepared m the ration varying from 85:15.
Example 11: The purification of blends prepared in Example 8, 9, 10 is done by treating it with thermally activated Bentonite clay in ratios of about 20% by weight of blends.
Example 12: The antioxidant IRGANOX1010 is added 0.8% by weight % in purified blends in example 11.
Example 13: The antioxidant IRGANOXL06 is added 0.6% by weight % in purified blends in example 11.
Example 14: The antioxidant IRGALUBE TPPT is added 0.7% by weight % in purified blends in example 11.
Example 15: The antioxidant DPA (Diphenyl amine) is added 0.4% by weight % in purified blends in example 13.
Example 16: The antioxidant BHT (Butylated hydrotoluene) is added in 0.8% by weight % in purified blends in example 14.
Example 17: The antioxidant TBHQ (Mono tertiary butyl hydroquinone) is added 0.8 % by weight in purified blends in example 12.
Example 18: The pour point depressant Evonik (1-300) is added 0.1% by weight % in Purified blends in example 15.

Example 19: The pour point depressant Infineum (V388) is added 0.2 % by weight % in Purified blends in example 15.
Example 20: The pour point depressant Rohm GmbH (Viscoplex 1-330) is added in 0.3% by weight % in Purified blends in example 15.
Example 21: The pour point depressant lubrizol (LZ7745 and LZ966) is added 0.6% by weight % in Purified blends in example 15.

CLAIMS :
1. We claim :An invention dealing with a novel application of Chemically Modified Mustard Oil (CMMO) and their derivatives as dielectric/insulating fluids which can be used in transformers, capacitors, switchgears, electric cables etc.
2. An invention as claimed in claim 1 above, wherein chemical modification of Mustard Oil is carried out by selective hydrogenation using nickel and/or platinum catalysts.
3. An invention as claimed in claim S above, wherein alkyl esters of mustard oil fatty acids are blended with the chemically modified Mustard Oil which controls viscosity of the insulating fluid and the blended oil is then fortified with antioxidant additives to form a new insulating fluid oil which has good oxidation resistance and electrical properties.
4. A new insulating fluid which is a blend of chemically modified Mustard Oil (CMMO) and long chain alkyl ester of CMMO fatty acids with heptyl, octyl, isooctyl, decyl alcohols or just CMMO alone with suitable antioxidants and pour point depressants as additives.
5. A new insulating fluid wherein the said mustard oil is refined bleached and deodourized.
6. A new insulating fluid wherein the above mentioned mustard oil is chemically modified.

7. An invention as claimed in claim 2 above wherein the chemical modification involves selective hydrogenation using a selective Nickel or Platinum catalysts.
8. A new insulating oil based on mustard oil containing saturated fatty acids in the range of 3% to 6%. high mono unsaturation in the range of 55% to 75%, low triunsaturated fatty acids 1% to 4% and low di unsaturation 12% to 15%.
9. New insulating oil wherein the chemically modified mustard oil is further blended with an alkyl ester in a blend ratio varying from 70:30 to 99:1.
10. A new insulating fluid wherein the said blend is purified by percolation through a combination of thermally activated and acid activated clays.
11. A new insulating fluid wherein the blending component-alkyl ester is made from chemically modified Mustard oil fatty acids esterified with heptyl, octyl, isooctyl, decyl alcohols.
12. A new insulating oil wherein the said purified blends are mixed with additives such as pour point additives and antioxidants
13. A new insulating fluid wherein the pour point depressants are chosen from polymethacrylates or polyolefines.
14. A new insulating fluid wherein the antioxidant consists of Phenolic, aminic or mixtures thereof.

15. A new insulating fluid formulated with additives as above has a viscosity in the range 40 cSt to 51 cSt at 40°C.
16. A new insulating fluid as formulated above has good oxidation resistance and electrical properties as specified in standards (ASTM D6871).
17. A new insulating fluid wherein the final formulation shows good flash and fire points.
18. A new insulating fluid wherein the formulated fluids are fully biodegradable as per OECD301C &301F test for biodegradability.