DESC:FIELD OF INVENTION
[001] The present invention relates to a synthetic compressor oil composition for industrial air compressors. The present invention further provides a process for preparing the synthetic compressor oil composition.

BACKGROUND OF THE INVENTION
[002] Compressor oil is designed to provide a long service life to compressor applications. Compressor oil is used in air compressors to lubricate the moving components of the compressor. The thermal stability and oxidation resistance of compressor oils helps to maintain cleaner compressors, thereby enabling longer running periods between scheduled maintenance and oil changes. In addition to this, the moving parts of the air compressor might wear down and decrease the life span of compressor if they are not properly lubricated.
[003] Conventionally, there are two types of compressor oil available in the market: standard and synthetic. Standard oil is made using mineral oil base. It is cheaper, having shorter service life and is ideal for medium-duty use. Synthetic air compressor oil is made using a synthetic base. Commonly used compressor oil is based on mineral oil (naphthenic oil type). Synthetic oil undergoes processing and is more refined than standard oil. This type of oil has longer service life, extend the life of compressor, consumed at a slower rate, stay cooler than standard oil, and can help in reducing various deposits.
[004] However, the main disadvantage of using conventional synthetic compressor oil composition is, that they do not provide a substantial service life to the compressors. Further, oils having excellent chemical and physical properties and those particularly suitable for screw type compressor even at high temperature and pressure are highly expensive and are not more frequent. Moreover, even at high price most of them fail to provide better thermal stability and oxidation resistance, hydrolytic stability, rust protection, foam resistance, copper corrosion resistance and anti-wear performance.
[005] EP1859012A1 relates to a lubricant composition comprising an ethylene/a-olefin inter-polymer having an average molecular weight of less than 10,000 g/mol as a base oil and at least one oil additive. The ethylene/a-olefin inter-polymer has at least one molecular fraction which elutes between 40 °C and 130 °C when fractionated using TREF, characterized in that the fraction has a molar co-monomer content of at least 5 percent higher than that of a comparable random ethylene inter-polymer fraction eluting between the same temperatures, wherein said comparable random ethylene inter-polymer has the same co-monomer(s) and has a melt index, density, and molar co-monomer content (based on the whole polymer) within 10 percent of that of the ethylene/a-olefin inter-polymer.
[006] However, said application discloses the composition to manufacture the base oil, one of the components of the synthetic compressor oil. It does not provide the composition for synthetic compressor oil with substantially high thermal stability and oxidation resistance, hydrolytic stability, rust protection, foam resistance, copper corrosion resistance and anti-wear performance.
[007] Therefore, there is a need to develop a composition for industrial synthetic oil compressor, that have substantially high oxidation resistance, hydrolytic stability, rust protection, foam resistance, copper corrosion resistance, anti-wear performance and yet is economical, user friendly and having increased shelf life of compressor.

OBJECTIVE OF THE INVENTION
[008] The primary objective of the present invention is to provide an oil composition for a industrial compressors.
[009] Another objective of the present invention is to provide a synthetic industrial compressor oil composition for a screw type compressor which is operated at relatively high temperature and pressure.
[010] Yet another objective of the present invention is to provide a compressor oil composition with substantially high oxidation stability which aids in maintaining a cleaner compressor.
[011] Another objective of the present invention is to provide a compressor oil composition with improved hydrolytic stability.
[012] Yet another objective of the present invention is to provide a compressor oil composition with improved rust protection.
[013] One objective of the present invention is to provide a compressor oil composition that is foam resistant.
[014] One more objective of the present invention is to provide a compressor oil composition with increased copper corrosion resistance.
[015] One more objective of the present invention is to provide a compressor oil composition with substantially low oil consumption rate and higher lubrication.
[016] One more objective of the present invention is to provide a compressor oil composition with anti-wear properties thereby increasing the service life of the compressor.
[017] Still further objective of the present invention is to provide a compressor oil composition that enables maintaining cleaner compressors, enabling longer running period between scheduled maintenance, thus reducing the maintenance frequency and increasing the service life of compressor.
[018] One more objective of the present invention is to provide an economical and user-friendly compressor oil composition and process thereof which obviates the disadvantages of prior art.

SUMMARY OF THE INVENTION
[019] In one aspect, the present invention is directed to a synthetic compressor oil composition comprising:
(a) at least one base oil in a range of 90 to 98 wt.%;
(b) at least one antioxidant in a range of 0.5 to 3.0 wt.%;
(c) at least one corrosion inhibitor in a range of 0.5 to 2.0 wt.%;
(d) at least one extreme pressure anti-wear additive in a range of 0.5 to 1.0 wt.%; and
(e) at least one antifoam additive in a range of 0.01 to 1.0 wt.%,
wherein the wt.% is based on the total weight of the composition.
[020] In an embodiment, the base oil has a kinematic viscosity ranging between 22 cSt to 100 cSt at about 40 ? determined according to ASTM 445.
[021] In an embodiment, the base oil is selected from a group comprising of isoparaffinic polyalphaolefins, group IV polyalphaolefins, and a combination thereof.
[022] In other embodiment, the antioxidant is selected from a group comprising of phenolic antioxidant, amine antioxidant, phosphate type antioxidant, and a combination thereof.
[023] In another embodiment, the antioxidant is 4-Octyl-N-phenylaniline.
[024] In yet another embodiment, the corrosion inhibitor is a liquid carboxylic acid which is a mixture of C4 to C9 carboxylic acids.
[025] In still another embodiment, the extreme pressure anti-wear additive is a salt of propionic acid.
[026] In an embodiment, the antifoam additive is a blend of siloxanes and synthetic hydrocarbon.
[027] Another aspect of the present invention is directed to a process for preparing the above synthetic compressor oil composition. In an embodiment, the process comprises mixing the following: at least one base oil, at least one antioxidant, at least one corrosion inhibitor, at least one extreme pressure anti-wear additive, and at least one antifoam additive, at a temperature ranging between 60-70 ?.
[028] Yet another aspect of the present invention is directed to a method for lubricating an industrial air compressor by applying the above synthetic compressor oil to one or more moving components of the industrial air compressor.

DETAILED DESCRIPTION OF INVENTION
[029] Before the compositions and formulations of the present invention are described, it is to be understood that this invention is not limited to particular compositions and formulations described, since such compositions and formulations may, of course, vary. It is also to be understood that the terminology used herein is not intended to be limiting since the scope of the present invention will be limited only by the appended claims.
[030] The terms “comprising”, “comprises” and “comprised of” as used herein are synonymous with “including”, “includes” or “containing”, “contains”, and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms “comprising”, “comprises” and “comprised of” as used herein comprise the terms “consisting of”, “consists” and “consists of”.
[031] In the following passages, different aspects of the present invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.
[032] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some, but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments, as would be understood by those in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination.
[033] Furthermore, the ranges defined throughout the specification include the end values as well, i.e., a range of 1 to 10 implies that both 1 and 10 are included in the range. For the avoidance of doubt, the applicant(s) shall be entitled to any equivalents according to applicable law.
[034] An aspect of the present invention relates to a synthetic compressor oil composition comprising:
(a) at least one base oil in a range of 90 to 98 wt.%;
(b) at least one antioxidant in a range of 0.5 to 3.0 wt.%;
(c) at least one corrosion inhibitor in a range of 0.5 to 2.0 wt.%;
(d) at least one extreme pressure anti-wear additive in a range of 0.5 to 1.0 wt.%; and
(e) at least one antifoam additive in a range of 0.01 to 1.0 wt.%,
wherein the wt.% is based on the total weight of the composition.
[035] In an embodiment, the base oil has a kinematic viscosity ranging between 22 cSt to 100 cSt at about 40?. In another embodiment, the base oil has a kinematic viscosity ranging between 25 cSt to 36 cSt, or 40 cSt to 50 cSt.
[036] In another embodiment, the base oil is selected from a group comprising of isoparaffinic polyalphaolefins, group IV polyalphaolefins, and a combination thereof.
[037] Suitable amounts of the base oil may be added in the composition. In an embodiment, the amount of the base oil in the composition is in range of 90-98wt.% based on the total weight of the composition. In another embodiment, the amount of the base oil ranges between 92-98wt.%, or 94-98wt.%, or 96-98wt.% based on the total weight of the composition.
[038] The antioxidant in the composition prevents the oxidation of parts of the compressor. In an embodiment, the antioxidant is selected from a group comprising of phenolic antioxidant, amine antioxidant, phosphate type antioxidant, and a combination thereof. Suitable examples of the phenolic antioxidant include Butylated hydroxytoluene (BHT), 2,6-Di-tert-butylphenol, Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), and combinations thereof. Suitable examples of amine antioxidant include N-phenyl-1-naphthylamine, 4-Octyl-N-phenylaniline, diphenylamine, phenothiazine, N-Phenyl-2-naphthylamine, and combinations thereof. Suitable examples of phosphate type antioxidant include Tris(2,4-di-tert-butylphenyl) Phosphite, Tris(nonylphenyl) Phosphite, Di(stearyl)pentaerythritol diphosphate, Phenyl diisodecyl phosphite, and combinations thereof.
[039] In an embodiment, the antioxidant is 4-Octyl-N-phenylaniline.
[040] Suitable amounts of the antioxidant may be added in the composition. In an embodiment, the antioxidant is present in the range of 0.5 to 3wt.% of the total weight of the composition. In an embodiment, the antioxidant is present in the range of 0.5 to 2wt.%, or 0.5 to 1.5wt.% of the total weight of the composition.
[041] The corrosion inhibitor in the composition reduces the corrosion rate of metal parts of the compressor which may be exposed to the environment. In an embodiment, the corrosion inhibitor is a liquid carboxylic acid which is a mixture of C4 to C9 carboxylic acids. In an embodiment, the liquid carboxylic acid includes an amine complexing agent and/or a carboxylic acid complexing agent. Suitable examples of amine complexing agent include ethylenediaminetetraacetic acid (EDTA) and triethanolamine (TEA). Further, suitable examples of carboxylic acid complexing agents include oxalic acid, and diethylenetriaminepentaacetic acid.
[042] Suitable examples of the C4 to C9 carboxylic acids include short to medium-chain carboxylic acids, such as butanoic acid (C4), pentanoic acid (C5), hexanoic acid (C6), heptanoic acid (C7), octanoic acid (C8), and nonanoic acid (C9).
[043] In another embodiment, the liquid carboxylic acid is a mixture of C4 to C9 carboxylic acids, and amine complexing agent, and/or carboxylic acid complexing agent.
[044] Suitable amounts of the corrosion inhibitor may be added in the composition. In an embodiment, the corrosion inhibitor is present in the range of 0.5 to 2wt.% of the total weight of the composition. In another embodiment, the corrosion inhibitor is present in the range of 0.5 to 1wt.%, or 0.6 to 1wt.% based on the total weight of the composition.
[045] The composition also includes extreme pressure anti-wear additive which protects metal parts from wear and tear during operation of the compressor. In an embodiment, the extreme pressure anti-wear additive is selected from zinc dithiophosphate (ZDP), zinc dialkyldithiophosphate (ZDDP), Tricresyl phosphate (TCP), Halocarbons (chlorinated paraffins), Glycerol mono oleate, Stearic acid, salts of propoanic acid, phosphorothionate, and a mixture thereof. In an embodiment, the extreme pressure anti-wear additive is a salt of propionic acid. In another embodiment, the extreme pressure anti-wear additive is 3-(Di-isobutoxy-thiophosphorylsulfanyl)-2-methyl-propionic acid.
[046] Suitable amounts of the extreme pressure anti-wear additive may be added in the composition. In an embodiment, the extreme pressure anti-wear additive is present in the range of 0.5 to 1wt.% of the total weight of the composition.
[047] The composition also includes the antifoam additive which inhibits the foam formation. In an embodiment, the antifoam additive is a blend of siloxanes and synthetic hydrocarbon. In an embodiment, the antifoam additive has a viscosity of less than 7 mm2/s determined according to ASTM D 445, and density ranging between 0.8 to 0.85 g/cm3 determined according to ASTM D4052.
[048] Suitable amounts of the antifoam additive may be added in the composition. In an embodiment, the antifoam additive is present in the range of 0.01 to 1wt.% of the total weight of the composition.
[049] In another embodiment, the combination of at least one of each of the aforesaid components, namely base oil, antioxidants, corrosion inhibitors, extreme pressure anti-wear additive and antifoam additive, in the specific range and proportions as indicated, results in a synthetic compressor oil composition with substantially high oxidation stability, anti-wear properties providing better shelf life to the compressor.
[050] In an embodiment, the synthetic compressor oil is applied to a screw type compressor and a reciprocating type compressor. The present composition has substantially higher oxidation stability, hydrolytic stability, rust protection, foam resistance, copper corrosion resistance and anti-wear performance. Further, the present composition is economical, user friendly and is highly efficient.
[051] Another aspect of the present invention relates to a process for preparing the synthetic compressor oil composition, as described hereinabove. Accordingly, the embodiments pertaining to the synthetic compressor oil composition are applicable here as well.
[052] In an embodiment, the process comprises mixing the following: at least one base oil, at least one antioxidant, at least one corrosion inhibitor, at least one extreme pressure anti-wear additive, and at least one antifoam additive, at a temperature ranging between 60-70?.
[053] In another embodiment, the process includes the steps of:
• heating the base oil at a temperature of 60-70 ? for a duration ranging between 45-65 minutes to obtain a uniform mixture,
• mixing the antioxidant, corrosion inhibitor and the extreme pressure anti-wear additive to the base oil for a duration of 30 minutes, and
• mixing the anti-foam additive at a temperature ranging between 60-70 ? temperature for a duration of 1-2 hours to obtain a homogenous transparent mixture.
[054] Yet another aspect of the present invention relates to a method for lubricating an industrial air compressor by applying the synthetic compressor oil composition, as described hereinabove, to one or more moving components of the industrial air compressor. Accordingly, the embodiments pertaining to the synthetic compressor oil composition are applicable here as well.
[055] Advantageously, the present invention provides a synthetic compressor oil composition that enables maintaining cleaner compressors, enabling longer running period between scheduled maintenance, thus reducing the maintenance frequency, and increasing the shelf life of compressor. The present composition also has substantially higher oxidation stability, hydrolytic stability, rust protection, foam resistance, copper corrosion resistance and anti-wear performance. Further, the present composition is economical, user friendly and is highly efficient.

EXAMPLES
[056] The present invention is more particularly described in the following examples that are intended as illustration only, since numerous modifications and variations within the scope of the present invention will be apparent to those skilled in the art. Unless otherwise noted, all parts, percentages and ratios reported in the following examples are on a weight basis, and all ingredients used in the examples were obtained or are available from the chemical suppliers.
[057] The synthetic compressor oil composition of the present invention was evaluated for its physio chemical properties such as Oxidation Stability, EP- TEST, Pass Load, Weld Load, 25 AW Test, Wear Scar Dia., Foam Characteristics tested according to the ASTM standards.
[058] Table 1 below shows the tests performed according to ASTM standards to measure the efficiency of the present composition.
Sr. No. Physico-Chemical Properties Test Standard Significance Desired
1 Oxidation Stability RPVOT, min ASTMD2272 -14a Rotating Pressure Vessel Oxidation Test (RPVOT) determines the oxidation stability of an oil. By use of pure oxygen, high pressure, high temperature and in the presence of water and copper catalysts at 150°C. Minimum 1000 minutes
2 EP- TEST Four Ball Tester The extreme pressure test using a four-ball tester determines the performance of the lubricant at extreme pressure conditions. About 30 mL lubricant is used for the test. The test is run for 10 seconds at room temperature. Loads are gradually applied until the lubricant film ruptures and all four balls are welded
Pass Load Min. 160
Weld Load Min. 200
3 AW Test, Wear Scar Dia., um ASTM D4172 B The anti-wear test of the lubricants is performed to investigate the wear-resisting properties of the lubricants. The tests are carried out as per standards at a specific temperature (75 deg. Celsius) and a specific load (392 N). About 30 mL lubricant is used during the test. Three balls are tightly fixed in the ball pot, and the fourth ball is fixed to the ball chuck. Lubricant is poured into the ball pot such that all the three fixed balls are submerged in the lubricant. The fourth ball is rotated at 1200 rpm. Generally, the test is run for an hour, and then the wear scars on the bottom balls are observed in an optical microscope. The wear scars of all the three bottom balls are measured, and the average of these wear scars is recorded Max. 500
4 Foam Stability, ml, After 10 Min Settling Time Sequence I ,II,III ASTM D 892 Foam test method is used to determine the foaming tendency and stability of foam in lubricating oils. The ASTM D892 foam test procedure has been developed at two different temperatures: 24 and 93.5 °C. Max 200 ml

[059] Example 1: Compressor Oil- 32 Grade
[060] The formulations of compressor oil comprising base oil having viscosity 32 cSt are disclosed in below Table 2.
[061] Table 2: Compressor Oil- 32 Grade – inventive and comparative formulations.
Ingredients F1
Formulation (wt.%)
F2 Formulation (wt.%) C1 Comp. Form. (wt.%) C2 Comp. Form. (wt.%) C3 Comp. Form. (wt.%) C4 Comp. Form. (wt.%) C5 Comp. Form. (wt.%)
Base oil (32 cST) 96.7 97.27 98.4 98.32 98.2 98.08 97.3
Antioxidant 1.5 1 3 0 1 1 1
Corrosion inhibitor 0.8 0.88 1 0.88 0 0.88 0.88
Extreme pressure anti-wear additive 1 0.82 0.5 0.77 0.77 0 0.82
Antifoam additive 0.03 0.04 0.03 0.03 0.03 0.04 0

[062] Physico-Chemical studies and observed efficiency of the above formulations are disclosed in table 3.
[063] Table 3: Physico-Chemical studies of Compressor Oil- 32 Grade
Sr No.
Physico-Chemical Properties Test Standard
F1 F2
C1 C2
C3 C4 C5
1 Oxidation Stability RPVOT, min ASTMD2272 -14a 1175 1180 1022 520 850 1100 1040
2 EP- TEST
Pass Load Four Ball Tester 160 160 126 126 100 100 126
Weld Load Four Ball Tester 200 200 160 160 126 126 160
3 AW Test, Wear Scar Dia., um ASTM D4172 B Four Ball Tester 370 370 358 400 460 760 410
4 Foam Stability, ml, After 10 Min Settling Time Sequence I ,II,III ASTM D 892 0/10/0 0/10/0 0/10/0 0/10/0 0/10/0 0/10/0 50/80/50

[064] It may be noted that the formulations 1 and 2 (F1 and F2) exhibit higher stability compared to the comparative formulations. The inventive formulation of the present invention also find application in extreme pressure conditions observed in compressors at high temperature and pressure. Furthermore, the formulations 1 and 2 exhibit anti-wear and rust proof properties, which enable cleaner compressors with longer shelf life.
[065] Example 2: Compressor Oil- 46 Grade
[066] The formulations of compressor oil comprising base oil having viscosity 46 cSt are disclosed in below table 4.
[067] Table 4: Compressor Oil- 46 Grade – inventive and comparative formulations.
Ingredients F3
Formulation (wt.%) F4 Formulation (wt.%) C6 Comp. Form. (wt.%) C7 Comp. Form. (wt.%) C8 Comp. Form. (wt.%) C9 Comp. Form. (wt.%) C10 Comp. Form. (wt.%)
Base oil (46 cST) 96.7 97.32 98.4 98.32 98.2 98.09 97.35
Antioxidant 1.5 1 3 0 1 1 1
Corrosion inhibitor 0.8 0.88 1 0.88 0 0.88 0.88
Extreme pressure anti-wear additive 1 0.77 0.5 0.77 0.77 0 0.77
Antifoam additive 0.03 0.03 0.03 0.03 0.03 0.03 0

[062] Physico-Chemical studies and observed efficiency of the above formulations is disclosed herein below table 5.
[068] Table 5: Physico-Chemical studies of Compressor Oil- 46 Grade
Sr No.
Physico-Chemical Properties Test Standard

F3 F4 C6 C7 C8 C9 C10
1 Oxidation Stability RPVOT, min ASTMD2272 -14a 1200 1896 1010 770 1000 1800 1678
2 EP- TEST
Pass Load Four Ball Tester 160 160 126 126 100 100 126
Weld Load Four Ball Tester 200 200 160 160 126 126 160
3 AW Test, Wear Scar Dia., um ASTM D4172 B Four Ball Tester 397 320 448 380 489 976 390
4 Foam Stability, ml, After 10 Min Settling Time Sequence I ,II,III ASTM D 892 0/0/0 0/0/0 0/10/0 0/10/0 0/0/0 0/0/0 40/50/40

[069] It may be noted that formulations 3 and 4 (F3 and F4) exhibit higher stability compared to comparative formulations. More than 98% base oil concentration and higher amounts of antioxidant negative impact the oxygen stability. Further, inventive formulation of the present invention find application in extreme pressure conditions observed in compressors at high temperature and pressure. Furthermore, the formulations 3 and 4 (F3 and F4) exhibit anti-wear and rust proof properties, which enables cleaner compressors with longer shelf life.
[070] Comparative Analysis:
[071] Tables 6 and 7 below show comparative analysis of the present composition and conventional synthetic compressor oil composition for base oil having viscosity 32 cSt and 46 cSt, respectively.
[072] Table 6: Compressor Oil- 32 Grade
Sr No. Test
Standard Conventional formula F2
1 Oxidation Stability RPVOT, min ASTMD2272 -14a 1000 1180
2 EP- TEST
Pass Load Four Ball Tester 126 160
Weld Load Four Ball Tester 160 200
3 AW Test, Wear Scar Dia., um ASTM D4172 B Four Ball Tester 412 370
4 Foam Stability, ml, After 10 Min Settling Time Sequence I ,II,III ASTM D 892 20/20/20 0/10/0

[073] Table 7: Compressor Oil-46 Grade
Sr No. Test
Standard Conventional formula F4
1 Oxidation Stability RPVOT, min ASTMD2272 -14a 950 1896
EP- TEST
2 Pass Load Four Ball Tester 126 160
Weld Load Four Ball Tester 160 200
3 AW Test, Wear Scar Dia., um ASTM D4172 B Four Ball Teste 542 320
4 Foam Stability, ml, After 10 Min Settling Time Sequence I ,II,III ASTM D 892 0/10/0 0/0/0

[074] It can be observed from tables 6 and 7 that the present invention results in higher oxygen stability compared to conventional compressor oils. Further, the composition of the present invention exhibits rust protection, foam resistance, copper corrosion resistance and anti-wear performance of the present synthetic oil compressor composition compared to the conventional compressor oils.
[075] The above results of the compressor oils allow its use in application for industrial air compressors such as rotary screw and reciprocating type. Further, the present invention provides cost effective, environment friendly yet effective synthetic compressor oil composition.
[076] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.
,CLAIMS:We Claim:
1. A synthetic compressor oil composition comprising:
(a) at least one base oil in a range of 90 to 98 wt.%;
(b) at least one antioxidant in a range of 0.5 to 3.0 wt.%;
(c) at least one corrosion inhibitor in a range of 0.5 to 2.0 wt.%;
(d) at least one extreme pressure anti-wear additive in a range of 0.5 to 1.0 wt.%; and
(e) at least one antifoam additive in a range of 0.01 to 1.0 wt.%,
wherein the wt.% is based on the total weight of the composition.

2. The synthetic compressor oil composition as claimed in claim 1, wherein the base oil has a kinematic viscosity ranging between 22 cSt to 100 cSt at about 40? determined according to ASTM 445.

3. The synthetic compressor oil composition as claimed in claim 1 or 2, wherein the base oil is selected from a group comprising of isoparaffinic polyalphaolefins, group IV polyalphaolefins, and a combination thereof.

4. The synthetic compressor oil composition as claimed in one or more of claims 1 to 3, wherein the antioxidant is selected from a group comprising of phenolic antioxidant, amine antioxidant, phosphate type antioxidant, and a combination thereof.

5. The synthetic compressor oil composition as claimed in one or more of claims 1 to 4, wherein the antioxidant is 4-Octyl-N-phenylaniline.

6. The synthetic compressor oil composition as claimed in one or more of claims 1 to 5, wherein the corrosion inhibitor is a liquid carboxylic acid which is a mixture of C4 to C9 carboxylic acids.

7. The synthetic compressor oil composition as claimed in one or more of claims 1 to 6, wherein the extreme pressure anti-wear additive is a salt of propionic acid.

8. The synthetic compressor oil composition as claimed in one or more of claims 1 to 7, wherein the antifoam additive is a blend of siloxanes and synthetic hydrocarbon.

9. A process for preparing the synthetic compressor oil composition as claimed in one or more of claims 1 to 8, comprising mixing the following: at least one base oil, at least one antioxidant, at least one corrosion inhibitor, at least one extreme pressure anti-wear additive, and at least one antifoam additive, at a temperature ranging between 60-70?.

10. A method for lubricating an industrial air compressor by applying the synthetic compressor oil composition as claimed in one or more of claims 1 to 8 to one or more moving components of the industrial air compressor.