(12) United States Patent (10) Patent No.: US 8,658,575 B2 Singh Et Al

USOO8658575B2

(12) United States Patent (10) Patent No.: US 8,658,575 B2 Singh et al. (45) Date of Patent: Feb. 25, 2014

(54) COMPOSITION OF INSULATING FLUID AND (58) Field of Classification Search PROCESS FOR THE PREPARATION USPC ...... 508/110, 192,563, 584,469,391 THEREOF See application file for complete search history. (75) Inventors: Arun Kumar Singh, Uttranchal (IN); (56) References Cited Naval Kishore Pandey, Uttranchal (IN); U.S. PATENT DOCUMENTS Ashok Kumar Gupta, Uttranchal (IN) 2,595,557. A * 5/1952 Worth et al...... 508, 313 (73) Assignee: Council of Scientific & Industrial 5,171.462 A * 12/1992 DeRosa et al. . ... 508/281 5,498,809 A * 3/1996 Emert et al...... 585/13 Research, New Delhi (IN) 5,652.201 A * 7/1997 Papay et al...... 508,228 6,340,658 B1 1/2002 Cannon et al. *) Notice: Subject to anyy disclaimer, the term of this 6,485,659 B1 1 1/2002 Goedde et al. patent is extended or adjusted under 35 6,491,809 B1* 12/2002 Briot et al...... 208/18 U.S.C. 154(b) by 1930 days. 6,645,404 B2 11/2003 Oommen et al. 6,726,857 B2 4/2004 Goedde et al. 7.339,088 B1* 3/2008 O'Brien et al...... 585,804 (21) Appl. No.: 11/386,576 2002/0010103 A1* 1/2002 Takayama et al...... 508.433 (22) Filed: Mar 21, 2006 * cited by examiner (65) Prior Publication Data Primary Examiner — Jim Goloboy US 2007/OO60484A1 Mar 15, 2007 (74) Attorney, Agent, or Firm — Abelman, Frayne & Schwab (30) Foreign Application Priority Data (57) ABSTRACT Dec. 9, 2005 (IN) ...... 3.336/DELA2005 This invention provides a composition of insulating fluid and process for the preparation thereofthat mainly contains alkyl (51) Int. Cl. benzenes. In addition to alkylbenzenes, the composition also CIOM IO5/06 (2006.01) contains an antioxidant, an antifoaming agent, a pour point CIOM. I.33/14 (2006.01) dispersant, a corrosion inhibitor and a detergent-dispersant CIOM 29/10 (2006.01) additive. The product of this invention has utility as an insu (52) U.S. Cl. lating fluid in electrical installations such as transformer. USPC ...... 508/110; 508/192:508/563; 508/584; 508/469; 508/391 16 Claims, No Drawings US 8,658,575 B2 1. 2 COMPOSITION OF INSULATING FLUID AND ers, as well as a greater degree of safety and environmental PROCESS FOR THE PREPARATION acceptability. This consist of aromatic hydrocarbons (di or tri THEREOF aryl ethane Such as biphenyl ethane or ethyl naphthalene), polyalphaolefins, polyol esters, and natural vegetable oils, FIELD OF THE INVENTION along with additives to improve pour point, increase stability and reduce oxidation rate. (blend of mineral oil, polyalpha The present invention relates to a composition insulating olefins, polyol esters and natural vegetable oils) fluid and process for preparation thereof. This invention par Reference may be made to U.S. Pat. No. 6,645,404 Oom ticularly relates to composition of insulating fluid that mainly men, et al. Nov. 11, 2003 ABB Technology AG (Zurich, CH) contains alkyl benzenes. In addition to alkylbenzenes, the 10 High oleic acid oil compositions and methods of making and composition also contains an antioxidant, an antifoaming electrical insulation fluids and devices comprising the same. agent, a pour point dispersant, a corrosion inhibitor and a High oleic acid triglyceride having the properties of a dielec detergent-dispersant additive. The product of this invention tric strength of at least 35 KV/100 mill gap, a dissipation factor has utility as an insulating fluid in electrical installations such of less than 0.05% at 25 NC., acidity of less than 0.03 mg as transformer. 15 KOH?g, electrical conductivity of less than 1 pS/m at 25NC., a flashpoint of at least 250 NC. and a pour point of at least-15 BACKGROUND OF THE INVENTION NC with additives are disclosed as electrical insulation fluids. Reference may be made to U.S. Pat. No. 6,340,658 Can Enhancing the life of an electrical transformer is an essen non, et al. Jan. 22, 2002 Wavely Light and Power (Waverly, tial part of a modern power operation technology. The aging Iowa) Vegetable-based transformer oil and transmission line or deterioration of insulating oil is normally associated with fluid. A vegetable oil-based electrically-insulating fluid is oxidation. Due to the presence of oxygen and water, insulat environmentally-friendly and has a high flashpoint and a high ing oil oxidizes even under ideal conditions. The insulating fire point. The base oil is hydrogenated to produce maximum properties of the oil are also affected by contaminants from possible stability of the oil, or alternatively, is a higher oleic the solid materials in the transformer dissolving in the oil. The 25 acid oil. The vegetable oils of the preferred embodiments are reaction between unstable hydrocarbons in the oil and oxy soybean or corn oils. The oil can be winterized to remove gen, moisture or other chemicals in the atmosphere, with the crystallized fats and improve the pour point of the base oil, assistance of accelerators such as heat, results in decay prod without the necessity of heating the oil. The base oil can also ucts in the oil. Mineral oil insulating fluids undergo oxidative be combined with an additive package containing materials degradation in the presence of oxygen to give a number of 30 specifically designed for improved pour point, improved oxidation products. The final products of oxidation are acidic cooling properties, and improved dielectric Stability. The materials that can affect the characteristics of the insulating fluid is useful in electrical components such as transformers fluid as well as damage the components of the electrical unit. and transmission lines. It also provides methods for making The high temperatures in due course cause the fluid to oxidize the fluid and fluid-filled electrical components. and ultimately produce sludge and soluble acid in Sufficient 35 A patent filled by the inventors of the present invention quantity to impair its heat transfer and dielectric efficiency. disclosed the use of Heavy Alkyl Benzene alkaline earth Sludge formation is the terminal stage of the deterioration metal Sulfonates are in use as detergent-dispersant-anti rust process. The acids formed in the process of oxidation attack additive in various types of lubricants (Patent application IPA on the cellulose fibers and metals forming metallic Soaps, number 1306/DEL/1998 & 1307/DEL/1998 by A. K. Singhet lacquers, aldehydes, alcohols and ketones which precipitate 40 all assigned to CSIR). The alkyl benzenes are mono, di and as heavy tarry acidic sludge on the insulation. Sludge appears poly Substituted alkyl aromatics having one benzene or tolu faster in heavily loaded, hot running and abused transformers ene aromatic ring and straight or branched paraffinic chains causing shrinkage of the insulation through leaching out var having carbon atoms 1 to 15 preferably 10 to 15, preferably nishes and cellulose materials. mono and dialkylbenzene. Alkylbenzenes are produced as The main purpose of transformer oil is to insulate and cool 45 by-products during the preparation of (1) linear alkylben the transformer. A specification is a good start, but to Success Zene (LAB) in detergent industry, (2) heavy aromatic pro fully find just the right oil for transformer, details are needed. duced in catalytic reformer, and (3) naphtha or gas steam All transformers and their requirements are different. And cracker liquid product. Alkylbenzene consists of Substituted right oils are needed that are tailored for each transformer's benzenes and no poly-aromatics/condensed ring or olefinic need for availability, performance and its geographical con 50 compounds are present in the alkylbenzenes. It can be used as ditions. The Naphthenic oils are the best, which have out an alternate to mineral base stock of lubricants. It will reduce standing properties for use in a transformer. Much due to their the hazard potential of the lubricants. It will provide required low viscosity at high temperatures and excellent solvency at properties such as good insulating, dissipation of heat, stabil very low temperatures. They also have high oxidation stabil ity, anti-corrosion properties and more eco-friendliness. ity and great electrical properties that make them the perfect 55 There is a need for developing new insulating fluid com choice for a transformer. position, which is free from harmful polynuclear aromatic In the prior art for producing Insulating fluids, generally, hydrocarbons generally found in mineral oil and produce less mineral oils or mineral oil with synthetic fluids or synthetic pollution. These objectives must be met, while simulta fluid alone were used. The focus has been on the use of such neously satisfying Stringent performance standards, e.g., oil base to enhance the performance. 60 good insulation, dissipation of heat, stability and anti-corro Reference may be made to U.S. Pat. No. 6,726.857 and S1O. U.S. Pat. No. 6,485,659 Goedde, et al. Apr. 27, 2004 Cooper Industries, Inc. (Houston, Tex.) Dielectric fluid having OBJECTIVES OF THE INVENTION defined chemical composition for use in electrical apparatus. The dielectric coolants for use in sealed, non-vented trans 65 The main object of the present invention is to provide a formers, and have improved performance characteristics, composition insulating fluid and process for preparation including decreased degradation of the paper insulating lay thereof which obviates the drawbacks as detailed above. US 8,658,575 B2 3 4 Another object of the present invention is to provide a hydroxybenzyl)mesitylene, tris(3,5-di-t-butyl-4- composition of insulating fluid and process for preparation hydroxybenzyl)isocyanurate or hindered piperidine thereof from alternate source based on alkyl benzenes carboxylic acids, acylated derivatives of 2,6-dihydroxy-9- obtained from various petrochemical or refinery waste azabicyclo[3.3.1 nonane or bicyclic hindered amines or streams such as heavy alkylates from LAB plants, higher 5 diphenylamines or dinaphthylamines, phenylnaphthyl aromatic from catalytic reformers or steam cracking plants. amines, N,N'-diphenylphenylenediamine or p-octyldipheny Yet another object of the present invention is to avoid the lamine, pp-dioctyl diphenylamine, N-phenyl-1-naphthy use of polynuclear aromatic hydrocarbons, a component of lamine, N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2- mineral oil and reducing pollution potential of the insulating naphthylamine, di-1-naphthylamine, di-2naphthylamine, fluid formulation. 10 N-alkyl phenothiazines, imino(bisbenzyl), 6-(t-butyl)phenol, Yet another object of the present invention is to provide 2,6-di-(t-butyl)phenol, 4-methyl-2,6-di-(t-butyl)phenol. 4,4'- excellent miscibility of formulated insulating fluid with min methylenebis(-2,6-di-(t-butyl)phenol), Methyl hydroxy eral, vegetable and synthetic oil in all proportions. hydro cinnamide, phenothiazines derivatives, alkylated SUMMARY OF THE INVENTION 15 5-amino tetrazole, di-ter. Butyl p-amino phenol and a mixture thereof. Accordingly the present invention provides a composition In yet another embodiment the detergent-dispersant used is of insulating fluid comprising selected from the group consisting of calcium alkylbenzene (i) base Stoke of tailored heavy alkylbenzene having car Sulfonate, sodium alkylbenzene Sulfonate, propylene teramer bon atom mainly C14 to C18 in the range of 98.0-99.8 Succinimide of pentaethylene hexamine, octyl phosphonates wt %, and a mixture thereof. (ii) anti-oxidant in the range of 0.006-0.05% by weight In yet another embodiment the anti-foaming agent used is (iii) detergent-dispersant in the range of 0.05-0.15% by selected from the group consisting of silicone oil, polyvinyl weight, alcohol, polyethers and a mixture thereof. (iv) anti-foaming agent in the range of 0.01 to 1.0% by 25 In yet another embodiment the pour point dispersant used weight, is selected from the group consisting of diethylhexyl adipate, (v) pour point dispersant in the range of 0.01 to 1.0% by polymethacrylate, polyvinylacrylate and a mixture thereof. weight, In yet another embodiment the corrosion inhibitor used is (vi) corrosion inhibitor in the range of 0.10-0.03% by selected from the group consisting of octyl 1H benzotriazole, weight, 30 ditertiary butylated 1H-Benzotriazole, propyl gallate, poly In yet another embodiment the composition of insulating oxyalkylene polyols, octadecylamines, nonyl phenol ethoxy fluid obtained has following characteristics: (i) Kinetic viscosity at 27°C. is in the range of 10-20 cst, lates, calcium phenolates of hydrogenated pentadecylphenol, (ii) Viscosity index 60-100, magnesium alkylbenzene Sulfonates and a mixture thereof. (iii) Oxidation stability Pass (IP 48/97) 35 The present invention further provides a process for the (iv) Rotatory bomb oxidation test (ROBOT) at 95° C. is preparation of a composition of insulating fluid, which com 300-400 min. prises fractionating heavy alkylate fractions of linear alkyl (v) Flash point 140-160° C., benzene (LAB) or crackers, at a temperature in the range of (vi) Pour point (-) 15-25°C., 210-310°C., under vacuum distillation to obtain desired frac (vii) Ash sulfated <0.05, 40 tions of alkylbenzene having carbon atom C14 to C18 and (viii) Copper Strip corrosion test 1A, viscosity in the range of 10-20 cstat about 27°C., removing (ix) Foam test ASTM D130 Pass, the oxidized product from the above alkyl fractions by known (x) Interfacial tension against water 40-60 N/m, methods to obtain a base stock, mixing 98.0-99.8 wt % of the (xi) Reactive sulfur-NIL, above said base stock, at least one anti-oxidant in the range of (xii) Electrical strength 35-55 KV. 45 0.006-0.05 W%, at least one detergent-dispersant in the range (xiii) Dissipation factor 0.00058 of 0.05-0.15 W%, at least one anti-foaming agent in the range (xiv) Specific resistance 39x10'’ Ohm, of 0.01 to 1.0 W%, at least one pour point dispersant in the (XV) SK value is 3-5, range of 0.01 to 1.0 W%, at least one corrosion inhibitor in the (xvi) Density at 20° C. is 0.880-0.884. range of 0.10-0.03 W%, under stirring, at a temperature in the (xvii) Biodegradability 40-60%. 50 range of 50-90° C. to obtain the desired insulating oil com In yet another embodiment the heavy alkylbenzene used is position. mono, di and poly Substituted alkyl aromatics having one In yet another embodiment the heavy alkylbenzene used is benzene aromatic ring and straight or branched paraffin mono, di and poly Substituted alkyl aromatics having one chains having carbon atoms 14 to 18. benzene aromatic ring and straight or branched paraffinic In yet another embodiment the heavy alkylbenzene frac 55 chains having carbon atoms mainly C14 to C18. tions (C14-18) used is obtained from mono and dialkyl In yet another embodiment the heavy alkylbenzene frac benzenes produced during the production of linear alkylben tions (C14-18) used is obtained from mono and dialkyl Zene (LAB) in detergent industry, heavy alkylaromatics pro benzenes produced during the production of linear alkylben duced in catalytic reformer, and naphtha orgas steam cracker Zene (LAB) in detergent industry, heavy alkyl aromatics pro liquid product or mixture thereof. 60 duced in catalytic reformer, and naphtha orgas steam cracker In yet another embodiment the anti-oxidant used is liquid product or mixture thereof. selected from the group consisting of 2,4,6-tri-tert-butylphe In yet another embodiment the anti-oxidant used is nol. 2,6-di-tert-butyl-4-n-butylphenol. 2,6-di-t-butyl-4-me selected from the group consisting of 2,4,6-tri-tert-butylphe thylphenol or n-octadecyl 3-(3,5-di-t-butyl-4-hydroxy phe nol. 2,6-di-tert-butyl-4-n-butylphenol. 2,6-di-t-butyl-4-me nyl)propionate, penta erythrityl tetrakis3-(3,5-di-t-butyl-4- 65 thylphenol or n-octadecyl 3-(3,5-di-t-butyl-4-hydroxy phe hydroxyphenyl)propionate, di-n-octadecyl(3,5-di-t-butyl-4- nyl)propionate, penta erythrity1 tetrakis3-(3,5-di-t-butyl-4- hydroxybenzyl)phosphonate, 2,4,6-tris(3,5-di-t-butyl-4- hydroxyphenyl)propionate, di-n-octadecyl(3,5-di-t-butyl-4- US 8,658,575 B2 5 6 hydroxybenzyl)phosphonate, 2,4,6-tris(3,5-di-t-butyl-4-hy (xiv) Specific resistance 39x10'’ Ohm, droxybenzyl)mesitylene, tris(3,5-di-t-butyl-4-hydroxyben (XV) SK value is 3-5, Zyl)isocyanurate or hindered piperidine carboxylic acids, (xvi) Density at 20° C. is 0.880-0.884, acylated derivatives of 2,6-dihydroxy-9-azabicyclo[3.3.1 (xvii) Biodegradability 40-60%.

Comparison of properties of insulating fluid

U.S. Pat. No. U.S. Pat. No. 64.85659 66454.04 Our claim SN. Properties mix vegetable alkylate Remarks 1 Kinetic Viscosity at 11.8 27°C., centistokes 2 Flash Point, C. 250 250 152 inferior but more than requirement of 140°C. 5 Electrical strength 35 35 45 Better 6 cost high high low Better 7 Polynuclear Aromatics yes O No Better presence nonane or bicyclic hindered amines or diphenylamines or The composition are significantly non-toxic having no dinaphthylamines, phenylnaphthyl amines, N,N'-diphe polynuclear aromatic, biodegradable in the range of 20 to nylphenylenediamine or p-octyldiphenylamine, pp-dioctyl 60%, Flash point 130 to 200° C., pour point less than (-)10° diphenylamine, N-phenyl-1-naphthylamine, N-phenyl-2- 25 C., Kinematic viscosity at 27°C. 2 to 27 cst, Interfacial naphthylamine, N-(p-dodecyl)phenyl-2-naphthylamine, tension 10-60 N/m, Electrical strength 30 to 80 KV. Dissipa di-1-naphthylamine, di-2naphthylamine, N-alkyl phenothi tion Factor 0.0001 to 0.00058, Sp.resistance 30-40x10', SK azines, imino(bisbenzyl), 6-(t-butyl)phenol. 2,6-di-(t-butyl) value 4 to 10, Oxidation stability (RoBOT) 200 to 400 min, phenol, 4-methyl-2,6-di-(t-butyl)phenol, 4,4'-methylenebis(- 30 water 1 to 40 ppm, TAN below 0.01 mgKOH, copper corro 2,6-di-(t-butyl)phenol), Methyl hydroxy hydro cinnamide, sion below 1 and able to replace the traditional mineral lube phenothiazines derivatives, alkylated 5-amino tetrazole, di oils. The main advantages are, it reduces use of petroleum, ter. Butyl p-amino phenol and a mixture thereof. offer better use of petrochemical waste product, cheaper than In yet another embodiment the detergent-dispersant used is synthetic oil, product is more biodegradable and eco-freindly selected from the group consisting of calcium alkylbenzene 35 than petroleum lubes, safe to use due to higher flashpoint and Sulfonate, sodium alkylbenzene Sulfonate, propylene teramer non-toxicity. Succinimide of pentaethylene hexamine, octyl phosphonates The following examples are given by the way of illustration and a mixture thereof. and therefore should not be construed to limit the scope of the A process according to claim 10, wherein the anti-foaming invention. agent used is selected from the group consisting of silicone 40 oil, polyvinyl alcohol, polyethers and a mixture thereof. EXAMPLE 1. In yet another embodiment the pour point dispersant used TAILORING OF ALKYLATE: commercial heavy alky is selected from the group consisting of diethylhexyl adipate, lates, a heavy waste fraction of detergent class linear alkyl polymethacrylate, polyvinylacrylate and a mixture thereof. benzene (LAB), was fractionated by vacuum distillation. The In yet another embodiment the corrosion inhibitor used is 45 lighter cut having 50 weight percent of total alkylate was selected from the group consisting of octyl 1H benzotriazole, taken for base-stock preparation. The typical properties of the ditertiary butylated 1H-Benzotriazole, propyl gallate, poly alkylate are oxyalkylene polyols, octadecylamines, nonyl phenol ethoxy lates, calcium phenolates of hydrogenated pentadecylphenol, magnesium alkylbenzene Sulfonates and a mixture thereof. 50 Density at 15° C., gm/ml O.8748 In yet another embodiment the lubricating oil composition Kinetic viscosity at 27°C., cSt 26.75 obtained has the following characteristics: Viscosity index 95 (i) Kinetic viscosity at 27°C. is in the range of 10-20 cst, Refractive index at 20°C. 148426 Pour point (-)27°C. (ii) Viscosity index 60-100, 55 Molecular weight 4035 (iii) Oxidation stability Pass (IP 48/97) RoBOT oxidation stability at 95°C. 200 minuts (iv) Rotatory bomb oxidation test (ROBOT) at 95° C. is Distillation range Up to 307 C. 300-400 min. Poly-aromatics or olefinic compounds Negligible (v) Flash point 140-160° C., (vi) Pour point (-) 15-25°C., 60 (vii) Ash sulfated <0.05, EXAMPLE 2 (viii) Copper Strip corrosion test 1A, (ix) Foam test ASTM D130 Pass, TAILORING OF ALKYLATE: commercial alkylates, a (x) Interfacial tension against water 40-60 N/m, waste alkylbenzene from cracker unit, was fractionated by (xi) Reactive sulfur-NIL, 65 vacuum distillation. The lighter cut having 55 weight percent (xii) Electrical strength 35-55 KV. of total alkylate was taken for base-stock preparation. The (xiii) Dissipation factor 0.00058 typical properties of the alkylate are US 8,658,575 B2 7 8

Density at 15° C., gm/ml O.8703 Electrical strength (breakdown) 39 KV Kinetic viscosity at 27°C., cSt 25.11 Kinetic viscosity at 27°C., cSt 25.83 Viscosity index 98 Viscosity index 104 Refractive index at 20° C. 148006 Oxidation Stability, IP 48/97 Pass - increase in viscosity 0.8% Pour point (-)22°C. Pour point (-)28°C. Molecular weight 408 - 5 ROBOT test 95°C. 220 minutes RoBOT oxidation stability at 95°C. 190 minuts Flash point 150° C. Distillation range Up to 291° C. Acid number, mg KOH O.OOS Poly-aromatics or olefinic compounds Negligible Poly-aromatics or olefinic compounds Negligible 10

EXAMPLE 6 EXAMPLE 3 Preparation of Lube Oil from Base Stock Preparation of Base Stock 15 The base stock was blended with additive octyl 5amino tetrazole as a high temperature anti-oxidant in 200 ppm, Tailored heavy alkylate was passed through silica gel col Methyl Hydroxy Hydro Cinnamate as low temperature anti umn to remove oxidized product or treated with absorbent oxidant-lubricity additives in 80 ppm, pentaethylene hexam clay Such as fuller's earth by mixing and thoroughly stirred ine dodecyl Succinimide as detergent-dispersant in 100 ppm, for 50 minutes at 80° C. and filtering it through G-4 sintered Silicone polymer oil as antifoaming agent pour point glass funnel. The typical physico-chemical characteristics of depressant and calcium HAB Sulfonate as corrosion inhibi the heavy alkylate are: tors having base number 500 in 150 ppm concentration. The doping was done at 60° C. with stirring for 2 hours. 25 Electrical strength (break down) 40 KV EXAMPLE 7 Kinetic viscosity at 27°C., cst 26.62 Viscosity index 104 Preparation of Lube Oil from Base Stock Oxidation Stability, IP 48/97 Pass - increase in viscosity 0.75% Pour point (-)28°C. The base stock was blended with additive p-p-dioctyl ROBOT test 95°C. 250 minutes diphenyl amine as a high temperature anti-oxidant in 100 Flash point 152° C. 30 ppm, Zinc dialkyl dithiophosphate as low temperature anti Acid number, mg KOH O.OOS oxidant-lubricity additives in 50 ppm, octyl phosphonate as Poly-aromatics or olefinic compounds Negligible detergent-dispersant in 100 ppm, poly vinyl acrylate as anti foaming agent pour point depressant and alkylbenzotriaz ole as corrosion inhibitors having base number 500 in 50 ppm 35 concentration. The doping was done at 60°C. with stirring for EXAMPLE 4 2 hours. Preparation of Base Stock EXAMPLE 8 Tailored alkylate from cracker unit was passed through silica gel column to remove oxidized product or treated with 40 Preparation of Lube Oil from Base Stock absorbent clay such as fuller's earth by mixing and thor The base stock was blended with additive di-t-butyl 4-me oughly stirred for 50 minutes at 80°C. and filtering it through thyl phenol as a high temperature anti-oxidant in 100 ppm, G-4 sintered glass funnel. The typical physico-chemical char Methyl Hydroxy Hydro Cinnamate as low temperature anti acteristics of the base oil was, oxidant-lubricity additives in 150 ppm, pentaethylene hex 45 amine propylene tetramer Succinimide as detergent-dispers ant in 100 ppm, polymethacrylate as antifoaming agent— pour point depressant and polyoxyalkylene polyol as Electrical strength (break down) 38 KV corrosion inhibitors in 150 ppm concentration. The doping Kinetic viscosity at 27°C., cst 24.03 was done at 60° C. with stirring for 2 hours. Viscosity index 109 50 Oxidation Stability, IP 48/97 Pass - increase in viscosity 0.79% Pour point (-)26° C. EXAMPLE 9 ROBOT test 95°C. 210 minutes Flash point 153° C. Preparation of Lube Oil from Base Stock Acid number, mg KOH O.OOS Poly-aromatics or olefinic compounds Negligible The base stock was blended with additive n-naphthyl 55 2-phenylamine as a high temperature anti-oxidant in 200 ppm, Zinc dialkyl dithiophosphate as low temperature anti oxidant-lubricity additives in 250 ppm, pentaethylene hex EXAMPLE 5 amine propylene tetramer Succinimide as detergent-dispers ant in 200 ppm, Silicone polymer oil as antifoaming agent— 60 pour point depressant and octadecyl amine as corrosion Preparation of Base Stock inhibitors in 150 ppm concentration. The doping was done at Tailored alkylate from cracker unit and LAB plant were 60° C. with stirring for 2 hours. passed through silica gel column to remove oxidized product. 50 wt % of heavy alkylate and 50 wt % of alkylate from EXAMPLE 10 cracker unit were mixed and thoroughly stirred for 50 minutes 65 at 60°C. The typical physico-chemical characteristics of the CHARACTERIZATION AND EVALUATION OF LUBE blended base oil was, OIL: The formulations were analyzed and evaluated as per US 8,658,575 B2 9 10 ASTM or BIS methods such as ASTM D445/BIS-14234, hydro cinnamide, phenothiazines derivatives, alkylated P25/56. K. Viscosity & Viscosity index, ASTM D92/BIS 5-amino tetrazole, di-ter. Butyl p-amino phenol and a mixture P21/69 Flash point, ASTM D1217/BIS-P16 Rel. Den thereof. sity, ASTM D130/BIS-P15 Copper corrosion, ASTM D97/ 4. The process according to claim 1, wherein the detergent BIS-P10 Pour point, ASTM D874/BIS-P4. Ash sulfated, 5 dispersant used is selected from the group consisting of cal ASTM D 664/BIS-P1 TAN, ASTM D4377/BIS-P40 Wa cium alkyl benzene Sulfonate, Sodium alkyl benzene Sul ter, IP280,306,307. Oxidation Test, ASTM D3711 Cock fonate, propylene teramer Succinimide of pentaethylene ing test. hexamine, octyl phosphonates and a mixture thereof. 5. The process according to claim 1, wherein the anti EXAMPLE 11 10 foaming agent used is selected from the group consisting of silicone oil, polyvinyl alcohol, polyethers and a mixture EVALUATION: The typical values estimated are, viscos thereof. ity cst at 27°C. was 11.8, viscosity index was 61, flash point 6. The process according to claim 1, wherein the pour point 152°C., pour point (-) 18°C., copper corrosion <1, Total acid depressant used is selected from the group consisting of number 0.001 mg KOH, Foaming test pass, biodegradability 15 diethylhexyl adipate, polymethacrylate, polyvinylacrylate 45%. Interfacial tension against water 51 N/m, reactive sulfur and a mixture thereof. nil, Electrical strength 45 KV. Dissipation factor 0.00058, 7. The process according to claim 1, wherein the corrosion Specific resistance 39x10', SK value 4. Oxidation stability inhibitor used is selected from the group consisting of octyl (RoBOT at 95°C.) 333 min, water 15 ppm, Density 20° C. 1H benzotriazole, ditertiary butylated 1H-Benzotriazole, pro 0.881 and oxidation inhibitor 0.15%. pyl gallate, polyoxyalkylene polyols, octadecyl amines, The advantage of this invention that the composition of the nonyl phenol ethoxylates, calcium phenolates of hydroge insulating fluid based on alkyl benzene obtained from an nated pentadecyl phenol, magnesium alkyl benzene Sul alternate source of the present invention is free from con fonates and a mixture thereof. densed aromatic, eco-friendly and provides better or equiva 8. The process according to claim 1, wherein the compo lent performance as mineral oil based insulating fluids. 25 sition obtained has the following characteristics: We claim: (i) Kinetic viscosity at 27 deg. C. is in the range of 10-20 1. A process for the preparation of a composition of insu CSt, lating fluid, which comprises fractionating heavy alkylate (ii) Viscosity index 60-100, fractions of linear alkyl benzene (LAB) or crackers, at a (iii) Oxidation stability Pass (IP48/97) temperature in the range of 210-310°C., under vacuum dis 30 (iv) Rotatory bomb oxidation test (ROBOT) at 95 deg. C. tillation to obtain dialkylbenzenes having 14 to 18 carbon is 300-400 min. atoms and viscosity in the range of 10-20 cstat about 27°C., (v) Flash point 140-160 deg. C., removing the oxidized product from the above alkyl fractions (vi) Pour point (-)15-25 deg. C., to obtain a base stock, mixing 98.0-99.8 wt % of the above (vii) Ash sulfated <0.05, said base stock, at least one anti-oxidant in the range of 35 (viii) Copper Strip corrosion test 1A, 0.006-0.05 W 96, at least one detergent-depressant in the (ix) Foam test ASTM D130 Pass, range of 0.05-0.15 W%, at least one anti-foaming agent in the (x) Interfacial tension against water 40-60 N/m, range of 0.01 to 1.0 W%, at least one pour point depressant in (xi) Reactive sulfur-NIL, the range of 0.01 to 1.0 W%, at least one corrosion inhibitor (xii) Electrical strength 35-55 KV. in the range of 0.10-0.03 W%, under stirring, at a temperature 40 (xiii) Dissipation factor 0.00058 in the range of 50-90° C. to obtain the desired insulating oil (xiv) Specific resistance 39*39x10' Ohmm, composition. (XV) SK value is 3-5, 2. The process according to claim 1, wherein the heavy (xvi) Density at 20 deg. C. is 0.880-0.884, alkyl benzene fractions (C14-18) used are obtained from (xvii) Biodegradability 40-60%. mono and dialkylbenzenes produced during the production 45 9. A composition of insulating fluid comprising: oflinear alkylbenzene (LAB) in the detergent industry, heavy (i) a base stock of tailored heavy alkylbenzene comprising alkyl aromatics produced in catalytic reformer, and naphtha a major portion of dialkylbenzene having a paraffin or gas steam cracker liquid product or mixture thereof. chain of 14 to 18 carbonatoms in the range of 98.0-99.8 3. The process according to claim 1, wherein the anti wt %, and obtainable by the process of claim 1, oxidant used is selected from the group consisting of 2.4.6- 50 (ii) anti-oxidant in the range of 0.006-0.05% by weight, tri-tert-butylphenol. 2,6-di-tert-butyl-4-n-butylphenol, 2,6- (iii) detergent-dispersant in the range of 0.05-0.15% by di-t-butyl-4-methylphenol or n-octadecyl 3-(3,5-di-t-butyl weight, 4-hydroxy phenyl)propionate, penta erythrityl tetrakis3-(3. (iv) anti-foaming agent in the range of 0.01 to 1.0% by 5-di-t-butyl-4-hydroxyphenyl)propionate, di-n-octadecyl(3. weight, 5-di-t-butyl-4-hydroxybenzyl)phosphonate, 2,4,6-tris(3,5- 55 (v) pour point depressant in the range of 0.01 to 1.0% by di-t-butyl-4-hydroxybenzyl)mesitylene, tris(3,5-di-t-butyl weight, 4-hydroxybenzyl)isocyanurate or hindered piperidine (vi) corrosion inhibitor in the range of 0.10-0.03% by carboxylic acids, acylated derivatives of 2,6-dihydroxy-9- weight, azabicyclo[3.3.1 nonane or bicyclic hindered amines or wherein the composition has electric strength in the range diphenylamines or dinaphthylamines, phenylnaphthyl 60 of 30-80 KV, dissipation factor in the range of 0.0001 to amines, N,N'-diphenylphenylenediamine or p-octyldipheny 0.00058 and specific resistance in the range of 30-40x lamine, pp-dioctyl diphenylamine, N-phenyl-1-naphthy 10' Ohmm. lamine, N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2- 10. The composition of insulating fluid according to claim naphthylamine, di-1-naphthylamine, di-2naphthylamine, 9 having the following characteristics: N-alkyl phenothiazines, imino(bisbenzyl), 6-(t-butyl)phenol, 65 (i) Kinetic viscosity at 27.degree. C. is in the range of 10-20 2,6-di-(t-butyl)phenol, 4-methyl-2,6-di-(t-butyl)phenol, 4,4'- CSt, methylenebis(-2,6-di-(t-butyl)phenol), Methyl hydroxy (ii) Viscosity index 60-100, US 8,658,575 B2 11 12 (iii) Oxidation stability Pass (IP 48/97) azabicyclo[3.3.1 nonane or bicyclic hindered amines or (iv) Rotatory bomb oxidation test (ROBOT) at 95.degree. diphenylamines or dinaphthylamines, phenylnaphthyl C. is 300-400 min. amines, N,N'-diphenylphenylenediamine or p-octyldipheny (v) Flash point 140-160.degree. C., lamine, pp-dioctyl diphenylamine, N-phenyl-1-naphthy (vi) Pour point (-) 15-25.degree. C. 5 lamine, N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2- (vii) Ash sulfated <0.05, naphthylamine, di-1-naphthylamine, di-2naphthylamine, (viii) Copper Strip corrosion test 1A, N-alkyl phenothiazines, imino(bisbenzyl), 6-(t-butyl)phenol, (ix) Foam test ASTM D130 Pass, 2,6-di-(t-butyl)phenol, 4-methyl-2,6-di-(t-butyl)phenol, 4,4'- (x) Interfacial tension against water 40-60 N/m, methylenebis(-2,6-di-(t-butyl)phenol), Methyl hydroxy (xi) Reactive sulfur-NIL, (xii) Electrical strength 35-55 10 hydro cinnamide, phenothiazines derivatives, alkylated KV, 5-amino tetrazole, di-ter. Butyl p-amino phenol and a mixture (xii) Dissipation factor 0.00058 thereof. (xiii) Electric strength 35-55 KV 13. The composition according to claim 9, wherein the (xiv) Specific resistance 39x10'’ Ohm, detergent-dispersant used is selected from the group consist (XV) SK value is 3-5, 15 ing of calcium alkylbenzene sulfonate, sodium alkylbenzene (xvi) Density at 20° C. is 0.880-0.884, Sulfonate, propylene tetramer succinimide of pentaethylene (xvii) Biodegradability 40-60%. hexamine, octyl phosphonates and a mixture thereof. 11. The composition according to claim 9, wherein the 14. The composition according to claim 9, wherein the heavy alkyl benzene fractions (C14-18) used are obtained anti-foaming agent used is selected from the group consisting from dialkyl benzenes produced during the production of ' of silicone oil, polyvinyl alcohol, polyethers and a mixture linear alkylbenzene (LAB) in detergent industry, heavy alkyl thereof. aromatics produced in catalytic reformer, and naphtha or gas 15. The composition according to claim 9, wherein the steam cracker liquid product or mixture thereof. pour point depressant used is selected from the group con 12. The composition according to claim 9, wherein the sisting of diethylhexyl adipate, polymethacrylate, polyviny anti-oxidant used is selected from the group consisting of lacrylate and a mixture thereof. 2.4.6-tri-tert-butylphenol. 2,6-di-tert-butyl-4-n-butylphenol, 16. The composition according to claim 9, wherein the 2,6-di-t-butyl-4-methylphenol or n-octadecyl 3-(3,5-di-t-bu corrosion inhibitor used is selected from the group consisting tyl-4-hydroxyphenyl)propionate, penta erythrityl tetrakis3 of octyl 1H benzotriazole, ditertiary butylated 1H-Benzotria (3,5-di-t-butyl-4-hydroxyphenyl)propionate, di-n-octadecyl Zole, propyl gallate, polyoxyalkylene polyols, octadecyl (3,5-di-t-butyl-4-hydroxybenzyl)phosphonate, 2,4,6-tris(3, '' amines, nonyl phenol ethoxylates, calcium phenolates of 5-di-t-butyl-4-hydroxybenzyl)mesitylene, tris(3,5-di-t- hydrogenated pentadecyl phenol, magnesium alkylbenzene butyl-4-hydroxybenzyl)isocyanurate or hindered piperidine sulfonates and a mixture thereof. carboxylic acids, acylated derivatives of 2,6-dihydroxy-9-