Ecofriendly and biodegradable lubricant formulation and process for preparation thereof

Abstract

The present invention discloses with the development of ecofriendly and biodegradable lubricant formulation useful for micro electro mechanical systems and process thereof. The new generation Mineral oil free lubricant formulations were developed by esterification of polyols such as 2,2-dimethyl, 1,3-Propanediol, 2,2-diethyl-1,3-propane diol, and aliphatic di carboxylic acids like adipic and azelaic and with mono alcohol, using heterogeneous catalyst Indion 140 with cation exchange properties. The said formulation has a viscosity in the range of 31 to 47 cSt at 40° C., a high viscosity index of 139-196, pour point of approximately <−39° C. with a multifunctional EP additive of recommended dose of 1.5-4%. These new generation lubricants exhibited excellent biodegradability, a high viscosity index, and a low pour point, a high flash point, good lubricity, good oxidative stability, very good protection, against wear, no evaporation loss, good adherence to metal, corrosion inhibiting characteristics and suitability for use with commercial additives. In addition the products are non toxic to the sewage bacteria.

Claims

1. A lubricant, wherein the lubricant comprises: polyol complex ester selected from the group consisting of 2,2-diethyl-1,3-propane-di-azelaic-2-ethyl-1-hexanoate; 2,2-dimethyl-1,3-propane-di-adipic-2-ethyl-1-hexanoate, and a mixture thereof, wherein the polyol complex is in the range of 94% to 100%; an antioxidant in the range of 0-2%; and an additive in the range of 0 to 4%; and wherein the lubricant is free of mineral oil.

2. The lubricant as claimed in claim 1, wherein the ratio of polyol complex esters is in the range of 1:1 to 1:3.

3. The lubricant as claimed in claim 1, wherein the ratio of polyol complex ester is 1:1.

4. The lubricant as claimed in claim 1, wherein the antioxidant is selected from the group consisting of 2,6-di tertiary butyl 4, methyl Phenol (BHT), alkylated diphenylamine, 3,7-di-t-octylphenothiazine, alkylated PANA, and di-t-butyl-p-cresol (DBPC).

5. The lubricant as claimed in claim 1, wherein the additive is selected from the group consisting of Zinc dialkyl dithio phosphate (ZDDP), 5,5-dithiobis-(1,3,4-thiadiazole-2(3H)-thione), Di Methyl Hydrogen Phosphite, Di Butyl Hydrogen Phosphite, Di-n-Octyl Hydrogen Phosphite, Di-2-Ethylhexyl Hydrogen Phosphite, Di Oleyl Hydrogen Phosphite, Di Lauryl Hydrogen Phosphite, Tri-Lauryl Tri Thiophosphite, Tri-Lauryl Phosphite, Tri-C.sub.12-C.sub.14 Phosphite, and Tri-C.sub.12-C.sub.14 Phosphite.

6. A process for synthesizing the mineral oil free lubricant wherein the process comprises the steps of: (i) reacting a mixture of polyol of C.sub.3-C.sub.5 carbon, dicarboxylic acid of C.sub.6-C.sub.10 carbon in a ratio of 1:2 in presence of a heterogeneous catalyst and a solvent at refluxing temperature for a period ranging between 2 to 4 hours to obtain a reaction mixture; (ii) removing water from said reaction mixture and allowing the mixture to cool to obtain cooled mixture; (iii) reacting the cooled mixture obtained at step (ii) with at least 2 moles of mono alcohol under reflux condition until all remaining carboxylic groups are esterified, and completing the reaction in a period ranging from 8 to 12 hours, until water is removed to obtain Polyol complex esters as base oil; and (iv) blending the base oil obtained at step (iii), wherein the base oil is 94% to 100% with antioxidant 1-2% and an additive 1.5 to 4%, to obtain the mineral oil free lubricant.

7. The process as claimed in claim 6, wherein the polyol is selected from the group consisting of 2, 2-dimethyl 1, 3-propane diol, and 2, 2-diethyl-1, 3-propane diol.

8. The process as claimed in claim 6, wherein the dicarboxylic acid (C.sub.6-C.sub.10) is selected from the group consisting of adipic acid, and azelaic acid.

9. The process as claimed in claim 6, wherein the mono alcohol in step (iii) is selected from the group consisting of 2-ethyl-1-hexanol, isooctanol, nonanol, and isodecanol.

10. The process as claimed in claim 6, wherein the solvent is selected from toluene or xylene.

11. The process as claimed in claim 6, wherein the antioxidant is selected from the group consisting of 2,6-di tertiary butyl 4, methyl Phenol (BHT), alkylated diphenylamine, 3,7-di-t-octylphenothiazine, alkylated PANA, and di-t-butyl-p-cresol (DBPC).

12. The process as claimed in claim 6, wherein the additive is selected from the group consisting of Zinc dialkyl dithio phosphate (ZDDP), 5,5-dithiobis-(1,3,4-thiadiazole-2(3H)-thione), Di Methyl Hydrogen Phosphite, Di Butyl Hydrogen Phosphite, Di-n-Octyl Hydrogen Phosphite, Di-2-Ethylhexyl Hydrogen Phosphite, Di Oleyl Hydrogen Phosphite, Di Lauryl Hydrogen Phosphite, Tri-Lauryl Tri Thio-phosphite, Tri-Lauryl Phosphite, Tri-C.sub.12-C.sub.14 Phosphite, and Tri-C.sub.12-C.sub.14 Phosphite.

13. The process as claimed in claim 6, wherein the heterogeneous catalyst is Styrene di-vinyl benzene copolymer resin with sulphonic acid functionality.

14. The process as claimed in claim 6, wherein the reaction temperature in steps (i) and (ii) is in the range of 107-115° C. at atmospheric pressure.

15. A polyol complex ester selected from the group consisting of: (i) 2, 2-diethyl 1, 3-propane di adipic 2 ethyl 1 hexanoate (DEADEH), (ii) 2, 2-diethyl 1, 3-propane diazelaic 2 ethyl 1 hexanoate (DEAZEH), (iii) 2, 2-diethyl 1, 3-propane disebacic 2 ethyl 1 hexanoate (DESEH), (iv) 1, 1, 1-trishydroxymethyl propane triazilaic 2 ethyl 1 hexanoate (THAZEH), (v) 1,1, 1-trishydroxymethyl propane trisebacic 2 ethyl 1 hexanoate (THSEH), and (vi) 1, 1, 1-trishydroxymethyl propane triadipic 2 ethyl 1 hexanoate (THADEH).

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) No systematic study has been carried out so far on the polyol complex esters as MEMS lube base stocks. In the present investigation, we report the studies carried out on the synthesis, physicochemical characterization and performance evaluation of polyol complex esters and suitability of these esters as lubricant formulations for chronometers and other delicate high precision components used in microelectromechanical systems.

(2) To the best of inventor's knowledge very few reports in the open literature are available on the preparation of polyol ester base stocks and its application in neat cutting oils and automotive gear oils. However the present invention intends towards development of a new lubricating composition that is ecofriendly and biodegradable for micro electro mechanical system applications.

(3) In the present investigation, we have synthesized complex esters of 2,2 di methyl 1,3 propane diol and 2,2 di ethyl 1,3 propane diol, adipic, azelaic acids and 2-ethyl 1-hexanol by using two step esterification with indigenous commercial ion exchange resin catalyst. The use of this catalyst has advantages over conventional catalysts, (i) being indigenous and (ii) recycled two times without loss of reactivity.

(4) The present invention thus overcomes all the shortcomings of the existing state of art. It describes biodegradable and eco-friendly new generation lube base stocks prepared by two step esterification of polyols such as 2,2-dimethyl, 1,3-Propanediol, 2,2-diethyl-1,3-propane diol and aliphatic di carboxylic acids like adipic and azelaic acids with mono alcohol using a heterogeneous ion exchange resin catalyst and its application in chronometers and other delicate precision components for MEMS based devices like delicate bearings, gauges, meters, clocks etc which are liable to be exposed to wide range of operating conditions.

(5) The present invention is to develop the ester base oil with excellent biodegradability, high viscosity index and low pour point, high flash point, very good lubricity, good oxidation stability and property of preventing corrosion and suitable for use with sealing materials.

(6) The present invention is to develop the ester base oil with the synthesized products when blended with Zinc dialkyl dithio phosphate (ZDDP) as multifunctional EP additive in recommended doses of 1.5-4% improve the weld load and antiwear performance by approximately 30%.

(7) One of the features is that the product passes the 100 hour oxidation stability test. After this anti oxidant additives 2,6-di tertiary butyl 4, methyl Phenol was added.

(8) One more feature of the invention is that the ester base oil with high purity polyol complex esters with negligible acidity. The products obtained by this invention can be used as biodegradable and ecofriendly lubricants in chronometers and other delicate components in MEMS devices and is completely ecofriendly and biodegradable as per ASTM D: 5864-2009 method where as hitherto conventional MEMS oils are not biodegradable containing mineral oil and PFPEs as base stock and synthesized using conventional catalysts.

(9) The ester base oil formulations for MEMS applications, by using commercial mineral oil additives which are being used in commercial formulations.

(10) Another feature of the invention is that invention provides an eco friendly and biodegradable MEMS lube base oils with polyol complex esters meeting the requirements of commercial chronometers and other delicate instrument oil specifications.

(11) Accordingly, the present invention provides a new, ecofriendly and biodegradable lubricant for micro electro mechanical systems. In this invention new generation lube base stocks were prepared by esterification of polyols such as 2,2-dimethyl, 1,3-Propanediol, 2,2-diethyl-1,3-propane diol, and aliphatic di carboxylic acids like adipic and azelaic acids and with mono alcohol, using Indion 140 as heterogeneous catalyst. More specifically this invention relates to employing these new generation lube base stocks for lubrication of chronometers and other delicate precision components like delicate bearings, gauges, meters, clocks etc for MEMS based devices which are likely to be exposed to wide range of operating conditions.

(12) Accordingly, the present invention relates to development of a new ecofriendly and biodegradable ester base stock for micro electro mechanical systems in a process comprising of: 1. Esterification of polyols with dicarboxylic acid and mono alcohols in the presence of heterogeneous catalyst wherein: (i) The di carboxylic acids belong to the carbon range of C.sub.6-C.sub.10 such as adipic and azelaic acids. (ii) The polyols belong to the range of C.sub.3-C.sub.5 such as 2,2-dimethyl, 1,3-Propanediol, 2,2-diethyl-1,3-propane diol and mono alcohol used was 2-ethyl-1-hexanol. (iii) The ratio of polyols to di carboxylic acids to mono alcohol falls in the range of 1:2:2 for synthesis of diols. (iv) The heterogeneous catalyst is Indion 140 used at a concentration of 25 (% wt) without loss of substantial reactivity even after 2 recycles. 2. Heating the reactants in the temperature range of 107 to 115° C. for the reaction time of 8-12 hrs to obtain complex esters. 3. Washing the products with water followed by drying and separating the product by recovery of solvent to develop a product with following characteristics: (i) Biodegradable MEMS lube base stocks synthesized from polyol alcohols. (ii) The formulated products have good lubricity and anti wear properties. (iii) The formulated product has excellent load bearing capacity. (iv) The ester base oil formulations obtained by this invention can be used as MEMS lubricating oils which are completely ecofriendly and biodegradable as per ASTM D: 5864-95 method where as hitherto conventional mineral based MEMS lubricating oils are not biodegradable.

(13) The present invention utilized the C.sub.3-C.sub.5 polyol alcohols, C.sub.6-C.sub.10 aliphatic di carboxylic acids and C.sub.8 mono alcohol, anti oxidant additive in a molar ratio of 1:2:2 as starting material in place of conventional oils which are toxic and non biodegradable.

(14) Another feature of the present invention is the use of non conventional indigenous commercial ion exchange resin Indion-140 as catalyst.

(15) In an embodiment of the present invention the polyol complex ester base oils may be selected from the viscosity range of 34.26 to 43.54 cSt at 40° C. as per IS: 1448: P-25 matching the specification and a high viscosity index of 161-171 as per P-56.

(16) In another embodiment of the present invention the polyol alcohols taken were 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol and mono alcohol, 2-ethyl-1-hexanol.

(17) In yet another embodiment of the present invention the acids used were aliphatic di carboxylic acids having carbon range of C.sub.6-C.sub.10 (adipic and azelaic acids).

(18) In yet another embodiment of the present invention the mono alcohol used was 2-ethyl-1-hexanol.

(19) In still another embodiment of the present invention the solvents used were toluene and xylene.

(20) In still another embodiment of the invention the heating was carried out in the temperature range of 107 to 115° C.

(21) In still another embodiment of the invention heating and stirring was continuously carried out from 8-12 hours.

(22) In still another embodiment of the invention the MEMS polyol complex esters were synthesized by using non conventional, indigenous, commercial ion exchange resin (Indion-140) catalyst.

(23) In still another embodiment of the present invention the recovered catalyst was used two times for diols without any loss of reactivity only reaction time was increased.

(24) In still another embodiment of the present invention the use of non conventional, indigenous, commercial catalyst affords the derived product with negligible acidity. The process has superiority with respect to ease of handling, less reaction time, high purity, cost effectiveness because of recyclable nature, energy saving and yields of the order of 90% and above.

(25) In still another embodiment of the present invention the synthesized esters were characterized by IR spectroscopy. The IR spectrum of polyol complex esters shows characteristic peak of ester at 1746 cm.sup.−1. The ester carbonyl frequency and the ester carbon-oxygen stretching appeared at 1746 cm.sup.−1 and 1158 cm.sup.−1 respectively. Strong band at lower frequency between 1158 and 1000 cm.sup.−1 are of aliphatic esters. Peak at 723 cm.sup.−1 is due to long alkyl chain present in lube. The ester carbon-hydrogen stretching and bending was observed at 3007-2854 cm.sup.−1 and 1379-1466 cm.sup.−1. There were no bands corresponding to —COOH and —OH groups indicating the total esterification of all the —CH.sub.2OH groups of alcohol and complete conversion of —COOH groups.

(26) In still another embodiment of the present invention the products of present invention for MEMS chronometer and other delicate instrument are completely biodegradable as per ASTM D: 5864-2004.

(27) In still another embodiment of the present invention the products of present invention which are non toxic to the sewage bacteria as per modified method of Algal inhibition test, official journal of the European communities No. L 383 A/179-185 (1993) can be used as lubricants for MEMS chronometer and other delicate instrument oils.

(28) The synthesized products have the following characteristics: a. The prepared esters have viscosity grade of 31.0 to 47.0 cSt at 40° C. as per P-25 matching the specification and a high viscosity index of 161-171 as per P-56. b. The synthesized products had a pour point of approximately <−39° C. as per IS: 1448: P-10. c. The Polyol complex esters showed superior flash points 210-232° C. against the specification as per ASTM D: 92. d. The biodegradability of the synthesized ester is above 95% as per the standard ASTM D: 5864 test method for biodegradability. e. The products are non toxic to the sewage bacteria. f. The conventional additives which are suitable for mineral oils are also giving positive response with this ester. g. The products have good anti wear properties with wear scar diameter of 0.350 mm at 40 kgf load as per ASTM D: 4172B. h. The products have excellent load bearing capacity. i. The products have good lubricity. j. The products have good oxidative stability. k. The products have no evaporation loss. l. The products have good adherence to metal characteristics. m. The products have good corrosion inhibiting characteristics. n. The synthesized polyol complex esters are comparable with an eco friendly and biodegradable MEMS lube base oils meeting the requirements of commercial chronometers and other delicate instruments oils specifications. o. Synthetic biodegradable polyol complex ester lubricating oils have excellent biodegradability, a high viscosity index and a low pour point, a high flash point, very good lubricity, good oxidative stability and property of preventing corrosion and suitable for use with sealing materials. p. The synthesis process employed yielded high purity polyol complex esters with negligible acidity. The products obtained by this invention can be used as a biodegradable and ecofriendly lubricants for MEMS chronometers and other delicate instrument oils which are completely ecofriendly, biodegradable as per ASTM D: 5864-2009 method where as hitherto conventional MEMS oils are not biodegradable containing mineral oil and PFPEs as base stock and synthesized by using conventional catalysts.

(29) The homogenous catalyst is Indion 140, which is a cationic ion exchange resin of macro porous cross-linked poly styrene (H+ ion 4.8 minimum dry, meq/gm, Wet, meq/ml 1.7 minimum) in —SO.sub.3H form with maximum operating temperature 150° C. Its appearance is grey spherical dry beads with particle size in the range of 0.42-1.2 mm. It contains 5% (maximum) moisture with pH in the range of 0-7.

(30) So far no lube base oils having polyol complex esters as base oils, polyol alcohols with di carboxylic acids and mono alcohol with ion exchange resin catalyst have been reported as lubricants for lubrication of delicate bearings, gears, gauges, meters, clocks etc. used in MEMS based devices.

(31) The present work is the development of new ecofriendly and biodegradable MEMS bio lube base oils which comprises, polyol alcohols (2,2-dimethyl-1,3-propane diol, 2,2-diethyl-1,3-propane diol, dibasic acids (adipic and azelaic) and mono alcohol(2-ethyl 1-hexanol) as end capping agent and non conventional indigenous commercial ion exchange resin Indion 140 catalyst with commercial additives. For the synthesis of MEMS bio lube base esters optimized reaction conditions are 1:2:2 mole of Polyol alcohol-di basic acid-mono alcohol, 25% non conventional ion exchange resin catalyst and reaction temperature 107 to 115° C. offering a conversion of 90-95% to ester. Non toxicity and biodegradability of the product and replacement to known commercial chronometer and other precision instrument oil products. The commercially available products are not biodegradable and are toxic containing mineral oils, fluoro ethers and PFPE lubricants as base stocks and synthesized by using conventional catalysts.

(32) The present invention uses non conventional, indigenous, ion exchange resin catalysts, use of commercial additives, Non toxicity and biodegradability, Replacement to known commercial chronometers and other delicate precision instrument oil products which are conventional Mineral oils, fluoro ethers and PFPE based lubricants having toxicity, non-biodegradability, limited performance and life.

(33) Significant technical advancement of the invention by using second step esterification i.e. use of mono alcohol are:

(34) Complex esters are made via the reaction of a polyol, a di carboxylic acid and a mono alcohol as end caping agent. Compared to di and polyol esters, these complex esters synthesized by using 2-ethyl hexanol as end capping agent have higher viscosities, due to formation of dimer, trimer and other oligomers. Complex esters prepared by this process have high conversion of the polyol moieties with low acid and hydroxyl number.

(35) Esters are normally synthesized by using p-toluene sulfonic acid, Ni, Cu, Fe, V, Co, and Sn based catalysts, Cu, Cr, oxides, alkoxy zirconate and heteropoly acids. In these processes the catalysts are used for once through application, have disposal problems, yield base oils which required continuous monitoring and somewhat inferior quality base oils with significant acidity and charred products.

(36) In the present investigation complex esters have been synthesized by using indigenous commercial ion exchange resin catalyst. The use of this catalyst has advantages over conventional catalysts, being indigenous and recycled two times without loss of reactivity. The process has superiority with respect to easy handling less reaction time lower molar ratio of alcohol to acid, high purity and cost effectiveness because of their recyclable nature and yields of the order of 90% and above. A simple cost effective efficient process for making synthetic complex ester base oils by use of a new catalyst system from indigenous raw materials has been developed for MEMS applications. The representative complex esters are as follows:

(37) ##STR00002##

EXAMPLES

(38) The following examples are given by way of illustration of the working of invention in actual practice and should not be construed to limit the scope of present invention in any way.

Example-1

2,2-dimethyl 1,3-propane di adipic 2 ethyl 1 hexanoate (DMADEH)

(39) To a mixture of 2,2-dimethyl 1,3-propane diol and adipic acid (1:2:2 mole, 10.4 g and 29.2 g) respectively was added 25% (16.2 g) of Indion 140 catalyst and toluene 100 ml. The contents were stirred by a mechanical stirrer and refluxed for 4 to 5 hours at 107 to 115° C., to get half ester half acid. After the removal of 3.6 ml of water (1st stage) the mixture was cooled and the contents were reacted with 2-ethyl-1-hexanol (26.0 g) under reflux until all the remaining —COOH groups were esterified. The reaction was completed in 8.30 hours by collecting 3.6 g of water (2nd stage) (3.6 g theoretical). The yield of the product was 92.8% conversion and unreacted materials were distilled out at 72° C. under vacuum (2 mm Hg). The product shows viscosities of 323.98, 31.00 at 0° C. & 40° C. respectively, viscosity index of 161 and pour point of >−39° C.

(40) The formulation is prepared using the Polyol ester: Anti oxidant (1%):ZDDP 1.5 of the polyol ester

Example-2

2,2-dimethyl 1,3-propane diazelaic 2 ethyl 1 hexanoate (DMAZEH)

(41) Experiment-1 was repeated under identical conditions except changing the aliphatic dicarboxylic acid, i.e., azelaic acid. 1:2:2 mole polyol, dicarboxylic acid, aliphatic mono alcohol (10.4 gms+37.6 gms+26.0 gms) and Indion 140 catalyst 25% (18.3 gms) respectively. The reaction was completed in 8.45 hours by collecting 3.6 g of experimental water (3.6 g theoretical). After the removal of water the contents were further heated for 1 to 2 hours, cooled, filtered, and 85 ml of solvent (toluene) was recovered. The yield of the product was 93.7%. The product shows lower viscosities of 5.60, 25.44 at 100° C. and 40° C. respectively, viscosity index of 169 and pour point of >−27° C.

Example-3

2,2-dimethyl 1,3-propane disebacid 2 ethyl 1 hexanoate (DMSEH)

(42) Experiment 1 was repeated under identical conditions except changing the acid part (1:2:2 moles, DMPD, Sebacic acid, 2-ethyl-1-hexanol (10.4 g+40.4 g+26.0 g) and 25% (19 g) Indion 140 catalyst respectively. The reaction was completed in 9 hours by collecting 3.6 g of experimental water in both the stages (3.6 g theoretical). After the removal of water the contents were further heated for 1 to 2 hours, cooled, filtered and 80 ml of solvent (toluene) was recovered. The yield of product was 91%. The product shows lower viscosities of 14.8, 90.33 at 100° C. and 40° C. respectively, viscosity index of 172 and pour point of >−24° C.

Example-4

2,2-diethyl 1,3-propane di adipic 2 ethyl 1 hexanoate (DEADEH)

(43) To a mixture of 2,2-diethyl-1,3-propane diol and adipic acid (1:2 mole 13.2 g+29.2 g) respectively was added 25% (17.0 g) of Indion 140 catalyst and toluene 100 ml. The contents were stirred by a mechanical stirrer and refluxed for 4 to 5 hours at 111° C., to get half ester half acid. After the removal of 3.6 g of water (1st stage) the mixture was cooled and the contents were reacted with 2-ethyl-1-hexanol (26 g) under reflux until all the remaining carboxylic groups were esterified. The reaction was completed in 5.45 hours by collecting 3.6 g of water (2nd stage) (3.6 g theoretical water). After the removal of water, the contents were further heated for 1-2 hours, cooled, filtered and 85 ml of toluene was recovered by vacuum distillation. The yield of the product was 92.1%. The product shows lower viscosities of 12.83, 91.3 at 100° C. and 40° C. respectively, viscosity index of 138 and pour point of >−24° C.

Example-5

2,2-diethyl 1,3-propane diazelaic 2 ethyl 1 hexanoate (DEAZEH)

(44) Experiment 4 was repeated under identical conditions except changing the aliphatic dicarboxylic acid, i.e., azelaic acid 1:2:2 mole DEPD, Azilaic acid, 2-ethyl-1-hexanol (13.2 g+37.6 g+26 g) and 25% (19 g) of Indion 140 catalyst respectively. The reaction was completed in 9 hours by collecting 3.6 g of experimental water in both the stages (3.6 g theoretical). After the removal of water the contents were further heated for 1 to 2 hours, cooled, filtered and 85 ml of solvent (toluene) was recovered. The yield of the product was 90.2%. The product shows lower viscosities of 408.23, 47.0 at 0° C. and 40° C. respectively, viscosity index of 171 and pour point of >−39° C.

(45) The formulation is prepared using the polyol ester: Anti oxidant (1%):ZDDP 3.5 of the polyol ester.

Example-6

2,2-diethyl 1,3-propane disebacic 2 ethyl 1 hexanoate (DESEH)

(46) Experiment 4 was repeated under identical conditions except changing the acid, i.e., sebacic acid 1:2:2 mole DEPD, sebacic acid, 2-ethyl 1-hexanol (13.2 g+40.4 g+26.0 g) and 25% of (19.7 g) Indion 140 catalyst respectively. The reaction was completed in 9.45 hours by collecting 3.6 g of experimental water in both the stages (3.6 g theoretical). After the removal of water, the contents were further heated for 1 to 2 hours, cooled, filtered and 80 ml of solvent (toluene) was recovered. The yield of the product was 91.9%. The product shows lower viscosities of 7.24, 36.8 at 100° C. and 40° C. respectively, viscosity index of 165 and pour point of >−39° C.

Example-7

1,1,1-trishydroxymethyl propane triadipic 2 ethyl 1 hexanoate (THADEH)

(47) To a mixture of THMP and adipic acid 1:3 mole (13.4 g+43.8 g) respectively was added 25% (23.7 g) of Indion 140 catalyst and toluene 100 ml. The contents were stirred by a mechanical stirrer and refluxed for 4 to 5 hours at 111° C., to get half ester half acid. After the removal of 8.4 g of experimental water (1st stage) the mixture was cooled and the contents were reacted with 2-ethyl 1-hexanol (39 g) under reflux until all the remaining carboxylic groups were esterified. The reaction was complete in 10.25 hours by collecting 5.4 g of water (2nd stage) (5.4 g theoretical). After the removal of water the contents were further heated for 1 to 2 hours, cooled, filtered, and 80 ml of toluene was recovered by vacuum distillation. The yield of the product observed was 94.4%. The product shows lower viscosities of 10.17, 26.51 at 100° C. and 40° C. respectively, viscosity index of 196 and pour point of >−15° C.

Example-8

1,1,1-trishydroxymethyl propane triazilaic 2 ethyl 1 hexanoate (THAZEH)

(48) Experiment 7 was repeated under identical conditions except changing the acid part i.e., azilaic acid 1:3:3 mole THMP, azilaic acid, 2-ethyl-hexanol (13.4 g+56.4 g+39 g) and 25% of (27 g) Indion 140 catalyst respectively. The reaction was completed in 9.45 hours by collecting 5.4 g and 5.2 g in both the stages (5.4 g theoretical). After the removal of water the contents were further heated for 1 to 2 hours, cooled, filtered and 80 ml of solvent (toluene) was recovered. The yield of the product was 92.7%. The product shows lower viscosities of 8.53, 46.07 at 100° C. and 40° C. respectively, viscosity index of 165 and pour point of >−27° C.

Example-9

1,1,1-trishydroxymethyl propane trisebacic 2 ethyl 1 hexanoate (THSEH)

(49) Experiment 7 was repeated under identical conditions except changing the acid part, i.e., sebacic acid 1:3:3 mole THMP, sebacic, 2-ethyl-hexanol (13.4 g+60.6 g+39 g) and 25% (28 g of Indion 140 catalyst respectively. The reaction was completed in 10.45 hours by collecting 5.4 g of experimental water in both the stages (5.4 g theoretical). After the removal of water (theoretical), content was further heated for 1 to 2 hours, cooled, filtered, and 80 ml of solvent (toluene) was recovered. The yield of the product was 94.3%. The product shows lower viscosities of 16.87, 111 at 100° C. and 40° C. respectively, viscosity index of 196 and pour point >−24° C.

(50) Based on the experiments 1-9, the physico-chemical characterization and performance evaluation of the products shows, examples 1 and 5 are matching the viscosities at 40° C. and other properties mentioned in the (IS-1088, 2004) specifications of lubricants for chronometers and are suitable as MEMS lubricants.

(51) The examples 10 & 11 given below are formulated with anti oxidant and EP additives to improve the oxidation and extreme pressure properties.

Example-10

(52) Experiment 5 was repeated under identical conditions except changing the aliphatic dicarboxylic acid, i.e., azelaic acid 1:2:2 mole DEPD, Azelaic acid, 2-ethyl-1-hexanol (13.2 g+37.6 g+26 g) and 25% (19 g) of catalyst respectively. The reaction was completed in 9 hours by collecting 3.6 g of experimental water in both the stages (3.6 g theoretical). After the removal of water the contents were further heated for 1 to 2 hours, cooled, filtered and 85 ml of solvent (toluene) was recovered. The yield of the base oil product was 90.2%. The product shows lower viscosities of 408.23, 47.0 at 0° C. and 40° C. respectively, viscosity index of 171 and pour point of >−39° C.

(53) The base oil is blended at recommended dose of 1% anti oxidant 2,6-di tertiary butyl 4, methyl Phenol (BHT) and 4% Zinc dialkyl dithio phosphate (ZDDP) based on the base oil. ZDDP is with alkyl groups containing branched and linear alkanes between 1-14 carbon lengths. A mixture of zinc dialkyl (C3-C6) dithiophosphates comes under CAS number 84605-29-8 as multifunctional EP additive.

Example-11

(54) To a mixture of 2,2-dimethyl 1,3-propane diol and adipic acid (1:2:2 mole, 10.4 g and 29.2 g) respectively was added 25% (16.2 g) of catalyst and toluene 100 ml. The contents were stirred by a mechanical stirrer and refluxed for 4 to 5 hours at 107 to 115° C., to get half ester half acid. After the removal of 3.6 ml of water (1st stage) the mixture was cooled and the contents were reacted with 2-ethyl-1-hexanol (26.0 g) under reflux until all the remaining —COOH groups were esterified. The reaction was completed in 8.30 hours by collecting 3.6 g of water (2nd stage) (3.6 g theoretical). The yield of the base oil product is 92.8% conversion and unreacted materials were distilled out at 72° C. under vacuum (2 mm Hg). The product shows viscosities of 323.98, 31.00 at 0° C. & 40° C. respectively, viscosity index of 161 and pour point of >−39° C.

(55) The base oil is blended at recommended dose of 1% anti oxidant 2, 6-di tertiary butyl 4, methyl Phenol (BHT) and 2.5% Zinc dialkyl dithio phosphate (ZDDP). The ZDDP use is with alkyl groups containing branched and linear alkanes between 1-14 carbon length. A mix of zinc dialkyl (C3-C6) dithiophosphates comes under CAS number 84605-29-8 as multifunctional EP additive.

Example-12

Mixture of (DMADEH) and (DEAZEH)

(56) Lubricant mixtures were prepared using synthesized nonconventional complex polyol lube base stock, which was blended with the known quantity of the other complex polyol. The blends in 1:1 and 1:2 ratios were homogenized by rigorous stirring on a magnetic hot plate at 100° C. for 2 hours. The complex polyol esters were easily mixed into homogeneous and clear blends. The lubricant blends reported no separation before and after the test. The as prepared lubricant blends were tested for their physico chemical properties and tribological performance.

Example-13

2,2-dimethyl 1,3-propane di adipic 2 ethyl 1 hexanoate (DMADEH)

(57) Experiment-1 was repeated under identical conditions except increasing the reaction temperature to (138° C.) as xylene was used as solvent. The reaction was completed in 6 hours and yield observed was 96%. On increasing the reaction temperature the reaction time and yield almost remains same. Hence the optimized reaction temperature for esterification was 107-115° C.

Example-14

2,2-dimethyl 1,3-propane di adipic 2 ethyl 1 hexanoate (DMADEH)

(58) Experiment-1 was repeated under identical conditions with 20% wt of Indion 140 catalyst. To a mixture of 2,2-dimethyl 1,3-propane diol and adipic acid (1:2:2 mole) was added 20% of Indion 140 catalyst and toluene 100 ml. The contents were stirred by a mechanical stirrer and refluxed for 4 to 5 hours at 111° C., to get half ester half acid. After the removal of water (1st stage) the mixture was cooled and the contents were reacted with 2-ethyl-1-hexanol under reflux until all the remaining —COOH groups were esterified. The reaction was completed in 8.30 hours by collecting 70% of water (2nd stage). The yield of the product was 78.8% conversion and unreacted materials were distilled out at 72° C. under vacuum (2 mm Hg).

Example-15

2,2-dimethyl 1,3-propane diadepic 2 ethyl 1 hexanoate; (DMADEH)

(59) Experiment-1 was repeated under identical conditions except increasing the Indion 140 catalyst to 25% wt. The reaction was completed in 8.30 hours by collecting 100% of experimental water (theoretical) 95 ml of solvent (toluene) recovered with the conversion of 92.8%.

Example-16

2,2-dimethyl 1,3-propane di adipic 2 ethyl 1 hexanoate; (DMADEH)

(60) Experiment-1 was repeated under identical conditions except increasing the catalyst to 30% wt. The reaction was completed in 8.30 hours with the conversion of 92.8%.

(61) Based on the above 12-14 experiments Indion 140 catalyst percentage used for esterification reaction under the optimized conditions was 25 wt %.

(62) Reactivity of the Catalyst

(63) In order to ensure life of the Indion 140 catalyst, the recovered catalyst was thoroughly washed with excess solvent (toluene) and dried at room temperature. The catalyst is recycled twice without any loss of reactivity.

Example-17

2,2-dimethyl 1,3-propane di 2 ethyl 1 hexanoate (DMADEH)

(64) Experiment-1 was repeated under identical conditions (1:2:2 mole of 2,2-dimethyl 1,3-propane diol, 2,2-di ethyl 1,3-propane diol/adipic, azelaic, sebacic acids/2-ethyl 1-hexanol) and 25% wt of Indion 140 catalyst. The reaction was completed in 8.30 hours and yield observed was 92.8%. The Indion 140 catalyst was recycled two times without any loss of reactivity, only reaction time was increased. At third time even after 18 hours, the reaction was not complete and yield observed was 40%.

(65) For the synthesis of the MEMS complex esters of DMPD and DEPD with adipic, azelaic acids and 2-ethyl-1-hexanol the optimized reaction conditions are 1:2:2 mole polyol, di acid and mono alcohol, 25% non conventional ion exchange resin Indion 140 catalyst and reaction temperature 107 to 115° C. offering a conversion of 90% to 95% to ester.

(66) The properties of synthesized products are compared with BIS specification 1088 for mineral oil based formulations and results are given below in table 1. The properties are better than BIS specification.

(67) TABLE-US-00001 TABLE 1 Comparison of physico chemical characteristics of synthesized products with BIS specification Requirements of Characteristics BIS specifications DEAZEH DMADEH Method Molecular weight 696 584 ASTM D: 2503, 1997 Molecular formula C.sub.41H.sub.76O.sub.8 C.sub.33H.sub.60O.sub.8 Density, d.sub.4.sup.20 gm/ml 0.9627 0.9915 ASTM D: 4052 KV in cst at 40° C., Min 30.0 47.00 31.00 P-25 0° C., Max 330.0 408.23 323.98 −35° C., Max 10000.0 >5000 >4000 Viscosity Index, Min 125 171 161 P-56 Oxidation stability, changes after test appearance No Turbity No Turbity No Turbity KV in cst at 40° C., Min 10 9.5 8.5 P-25 Copper spiral No sign of No corrosion No corrosion corrosion Evaporation loss, % by 1 0.42 0.48 P-136 mass, Max Adherence to metal, 15 13 12 change in diameter of the drop, percent, Max Protection Appearance of oil No change in Clear yellow Clear yellow colour Steel cube No corrosion No corrosion No corrosion Brass cube No discoloration No discoloration No discoloration Pour Point ° C., −39 <−39 <−39 P-10 Max Acidity, (mg P-2 KoH/gm of oil), Max Inorganic Nil Nil Nil Organic 1.0 0.0635 0.0817 Steel/steel 0.155 0.098 0.117

(68) The synthesized products also have good tribological properties as given in Table 2.

(69) TABLE-US-00002 TABLE 2 Tribological performance of synthesized products Characteristics DEAZEH DMADEH Weld Load(kgf) 240 190 Wear Scar Diameter(mm) 0.350 0.425 EHD film thickness at 30N (nm) 145 180 Average friction coefficient at 30N (μm) 0.098 0.117 EHD scar dia meter at 30N(μm) 186 182 DEAZEH: 2-diethyl, 1,3-Propane-Di azelaic-2-ethyl-1-hexanoate DMADEH: 2,2-dimethyl, 1,3-Propane-Di adipic-2-ethyl-1-hexanoate

Advantages of the Invention

(70) 1. Superior alternative to conventional mineral oil and Perfluoropolyether based commercial MEMS lube base oils on account of its ecofriendly and biodegradable nature. 2. The main advantages of synthesized products are good lubricity properties. 3. The main advantage of synthesized product is having excellent load bearing capacity. 4. The main advantage of synthesized product is conventional additives which are suitable for mineral oils are also giving positive response with this ester. 5. The main advantage of synthesized product is it passes the 100 hour oxidation stability test. After this anti wear and anti oxidant additives 2, 6-di tertiary butyl 4, methyl Phenol was used. 6. The synthesized polyol complex esters are good potential for use as biodegradable base stock for formulation of new eco-friendly and biodegradable MEMS chronometers and other delicate instrument oils. 7. The main advantage of synthesized product is the use of non conventional indigenous commercial Indion-140 ion exchange resin catalyst. 8. The product synthesized by using non conventional catalysts is a new potential candidate, for biodegradable MEMS chronometers and other delicate instruments oils which is completely ecofriendly, biodegradable and a replacement for currently being used conventional based products which are toxic and non-biodegradable.