Polymeric-inorganic nanoparticle compositions, manufacturing process thereof and their use as lubricant additives

Abstract

The invention relates to polymeric-inorganic nanoparticle compositions and preparation processes thereof. The invention also relates to an additive and lubricant compositions comprising these polymeric-inorganic nanoparticle compositions, as well as to the use of these polymeric-inorganic nanoparticle compositions in an oil lubricant formulation to improve tribological performance, in particular to improve extreme pressure performance and friction reduction on metal parts.

Claims

1. A polymeric-inorganic nanoparticle composition, obtained by milling a mixture, the mixture comprising one or more intercalation compound (A) and one or more polymer compound (B), (A) wherein the one or more intercalation compound comprises a metal chalcogenide having molecular formula MX.sub.2, where M is a metallic element selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg) and combinations thereof, and X is a chalcogen element selected from the group consisting of sulfur (S), selenium (Se), tellurium (Te), oxygen (O) and combinations thereof; and (B) wherein the one or more polymer compound is obtainable by polymerizing a monomer composition comprising: a) one or more functional monomer as component a) selected from the list consisting of: a1) hydroxyalkyl (meth)acrylates; a2) aminoalkyl (meth)acrylates and aminoalkyl (meth)acrylamides; a3) nitriles of (meth)acrylic acid and other nitrogen-containing (meth)acrylates; a4) aryl (meth)acrylates, where the acryl residue in each case can be unsubstituted or substituted up to four times; a5) carbonyl-containing (meth)acrylates; a6) (meth)acrylates of ether alcohols; a7) (meth)acrylates of halogenated alcohols; a8) oxiranyl (meth)acrylate; a9) phosphorus-, boron- and/or silicon-containing (meth)acrylates; a10) sulfur-containing (meth)acrylates; a11) heterocyclic (meth)acrylates; a12) maleic acid and maleic acid derivatives; a13) fumaric acid and fumaric acid derivatives; a14) vinyl halides; a15) vinyl esters; a16) vinyl monomers containing aromatic groups; a17) heterocyclic vinyl compounds; a18) vinyl and isoprenyl ethers; a19) methacrylic acid and acrylic acid, and one or both of the components selected from the group consisting of: b) one or more alkyl (meth)acrylate monomer; and c) the reaction product of one or more ester of (meth)acrylic acid and one or more hydroxylated hydrogenated polybutadiene having a number-average molecular weight (M.sub.n) of 500 to 10,000 g/mol, and wherein the weight ratio of the one or more intercalation compound (A) to the one or more polymer compound (B) is from 20:1 to 1:5.

2. The polymeric-inorganic nanoparticle composition according to claim 1, wherein in component b) each of the alkyl group of the one or more alkyl (meth)acrylate monomers independently is linear, cyclic or branched and comprises from 1 to 40 carbon atoms.

3. The polymeric-inorganic nanoparticle according to claim 2, wherein each of the one or more alkyl (meth)acrylate monomers independently is b1) of formula (I): ##STR00004## wherein R is hydrogen or methyl, R.sup.1 means a linear, branched or cyclic alkyl residue with from 1 to 8 carbon atoms, or b2) of formula (II): ##STR00005## wherein R is hydrogen or methyl, R.sup.2 means a linear, branched or cyclic alkyl residue with from 9 to 15 carbon atoms, or b3) of formula (III): ##STR00006## wherein R is hydrogen or methyl, R.sup.3 means a linear, branched or cyclic alkyl residue with from 16 to 40 carbon atoms.

4. The polymeric-inorganic nanoparticle composition according to claim 1, wherein the one or more polymer compound (B) is obtained by polymerizing a monomer composition comprising components a) and b), but not component c), and wherein the one or more polymer compound (B) has a weight-average molecular weight (M.sub.w) of from 5,000 to 300,000 g/mol.

5. The polymeric-inorganic nanoparticle composition according to claim 1, wherein the one or more polymer compound (B) is obtainable by polymerizing a monomer composition comprising components a) and c), and component b), and wherein the one or more polymer compound (B) has a weight-average molecular weight (M.sub.w) of from 10,000 to 1,000,000 g/mol.

6. The polymeric-inorganic nanoparticle composition according to claim 1, wherein the weight ratio of the one or more intercalation compound (A) to the one or more polymer compound (B) is from 10:1 to 1:2.

7. The polymeric-inorganic nanoparticle composition according to claim 1, wherein the one or more polymer compound (B) is obtainable by polymerizing a monomer composition comprising: a) from 1 to 60% by weight, of the one or more functional monomer as component a), based on the one or more polymer compound (B); and b1) from 0 to 50% by weight, of the one or more alkyl (meth)acrylate monomer as component b), based on the one or more polymer compound (B); and b2) from 40 to 99% by weight, of the one or more alkyl (meth)acrylate monomer as component b), based on the one or more polymer compound (B); wherein the amount of all monomers of the monomer composition sum up to 100% by weight.

8. The polymeric-inorganic nanoparticle composition according to claim 1, wherein the one or more polymer compound (B) is obtainable by polymerizing a monomer composition comprising: a) from 1 to 60% by weight, of the one or more functional monomer as component a), based on the one or more polymer compound (B); and b) from 10 to 95% by weight, of the one or more alkyl (meth)acrylate monomer as component b), based on the one or more polymer compound (B); and c) from 1 to 89% by weight, of the reaction product of one or more ester of (meth)acrylic acid and one or more hydroxylated hydrogenated polybutadiene having a number-average molecular weight (Mn) of from 500 to 10,000 g/mol as component c), based on the one or more polymer compound (B); wherein the amount of all monomers of the monomer composition sum up to 100% by weight.

9. A method for manufacturing a polymeric-inorganic nanoparticle composition as defined in claim 1, the method comprising the steps of: (a) providing one or more intercalation compound (A); (b) providing one or more polymer compound (B); (c) providing a solvent (C); (d) combining at least the one or more intercalation compound (A) and the one or more polymer compound (B) to obtain a mixture, combining at least the one or more intercalation compound (A), the one or more polymer compound (B) and the solvent (C) to obtain a mixture; and (e) milling the mixture.

10. The method according to claim 9, wherein at least the one or more intercalation compound (A), the one or more polymer compound (B) and the solvent (C) are combined to obtain the mixture, and wherein the step (e) comprises milling the mixture via a ball mill process, introducing from 0.1 to 10 kWh/kg, energy into the mixture.

11. An additive for a lubricant composition comprising the polymeric-inorganic nanoparticle composition according to claim 1.

12. A formulation comprising: (a) a base oil; and (b) a polymeric-inorganic nanoparticle composition according to claim 1.

13. The formulation according to claim 12, wherein the base oil is selected from the list consisting of an API Group I base oil, an API Group II base oil, an API Group III base oil, an API Group IV base oil and an API Group V base oil, or a mixture of one or more of these base oils.

14. The formulation according to claim 12, comprising (i) from 40 to 95% by weight, of base oil and (ii) from 5 to 60% by weight, of the polymeric-inorganic nanoparticle composition, based on the total weight of the formulation.

15. The formulation according to claim 12, comprising (i) from 50 to 99.99% by weight, of base oil and (ii) from 0.01 to 50% by weight, of the polymeric-inorganic nanoparticle composition, based on the total weight of the formulation.

16. The polymeric-inorganic nanoparticle according to claim 2, wherein each of the one or more alkyl (meth)acrylate monomers independently is b1) of formula (I): ##STR00007## wherein R is hydrogen or methyl, R.sup.1 means a linear, branched or cyclic alkyl residue with 1 to 5 carbon atoms, or b2) of formula (II): ##STR00008## wherein R is hydrogen or methyl, R.sup.2 means a linear, branched or cyclic alkyl residue with from 12 to 15 carbon atoms, or b3) of formula (III): ##STR00009## wherein R is hydrogen or methyl, R.sup.3 means a linear, branched or cyclic alkyl residue with from 16 to 30 carbon atoms.

17. The polymeric-inorganic nanoparticle composition according to claim 1, wherein the one or more polymer compound (B) is obtained by polymerizing a monomer composition comprising components a) and b), but not component c), and wherein the one or more polymer compound (B) has a weight-average molecular weight (M.sub.w) of from 10,000 to 200,000 g/mol.

18. The polymeric-inorganic nanoparticle composition according to claim 1, wherein the one or more polymer compound (B) is obtainable by polymerizing a monomer composition comprising components a) and c), and component b), and wherein the one or more polymer compound (B) has a weight-average molecular weight (M.sub.w) of from 200,000 to 500,000 g/mol.

19. The polymeric-inorganic nanoparticle composition according to claim 1, wherein the weight ratio of the one or more intercalation compound (A) to the one or more polymer compound (B) is from 4:1 to 1:2.

20. The polymeric-inorganic nanoparticle composition according to claim 1, wherein the one or more polymer compound (B) is obtainable by polymerizing a monomer composition comprising: a) from 2 to 40% by weight, of the one or more functional monomer as component a), based on the one or more polymer compound (B); and b1) from 0 to 10% by weight, of the one or more alkyl (meth)acrylate monomer as component b), based on the one or more polymer compound (B); and b2) 65 to 97% by weight, of the one or more alkyl (meth)acrylate monomer as component b), based on the one or more polymer compound (B); wherein the amount of all monomers of the monomer composition sum up to 100% by weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For the purpose of better illustrating the advantages and properties of the claimed polymeric-inorganic particles object of the invention, several graphs are attached as non-limiting examples:

(2) FIG. 1 is a diagram showing the friction reduction in % in boundary regime.

(3) FIG. 2 is a bar chart comparing the four ball weld results of the composition according to the invention with prior art compositions.

(4) FIG. 3 is a Transmission Electron Microscope (TEM) image of an original intercalation compound of IF-WS.sub.2 prepared in isopropanol/water, dispersed and dried.

(5) FIG. 4 is a Transmission Electron Microscope (TEM) image of the same intercalation compound of IF-WS.sub.2 after ball milling treatment according to the present invention, the image being taken after centrifugation and washing with chloroform.

EXPERIMENTAL PART

(6) The invention is further illustrated in detail hereinafter with reference to examples and comparative examples, without any intention to limit the scope of the present invention.

(7) Abbreviations C.sub.1 AMA C.sub.1-alkyl methacrylate (methyl methacrylate; MMA) C.sub.4 AMA C.sub.4-alkyl methacrylate (n-butyl methacrylate) C.sub.12-14 AMA C.sub.12-14-alkyl methacrylate C.sub.12-15 AMA C.sub.12-15-alkyl methacrylate OCTMO Octyltrimethoxysilan DMAPMAA N-3-Dimethylaminopropylmethacrylamid f.sub.branch degree of branching in mol % MA-1 macroalcohol (hydroxylated hydrogenated polybutadiene M.sub.n=2,000 g/mol) MM-1 macromonomer of MA-1 with methacrylate functionality M.sub.n number-average molecular weight M.sub.w weight-average molecular weight NB3020 Nexbase® 3020, Group III base oil from Neste with a KV.sub.100 of 2.2 cSt NB3043 Nexbase® 3043, Group III base oil from Neste with a KV.sub.100 of 4.3 cSt NB3060 Nexbase® 3060, Group III base oil from Neste with a KV.sub.100 of 6.0 cSt VISCOBASE 5-220 VISCOBASE® 5-220 is a group V synthetic base fluid from Evonik with a KV100 of 480 cSt VISCOPLEX 14-520 defoamer DI package Afton HiTec® 307 (detergent inhibitor) PPD Pour point depressant PDI Polydispersity index, molecular weight distribution calculated via M.sub.w/M.sub.n MTM Mini Traction Machine equipment

(8) Synthesis of a Hydroxylated Hydrogenated Polybutadiene (Macroalcohol) MA-1

(9) The macroalcohol was synthesized by anionic polymerization of 1,3-butadiene with butyllithium at 20-45° C. On attainment of the desired degree of polymerization, the reaction was stopped by adding propylene oxide and lithium was removed by precipitation with methanol. Subsequently, the polymer was hydrogenated under a hydrogen atmosphere in the presence of a noble metal catalyst at up to 140° C. and 200 bar pressure. After the hydrogenation had ended, the noble metal catalyst was removed and organic solvent was drawn off under reduced pressure to obtain a 100% macroalcohol MA-1.

(10) Table 2 summarizes the characterization data of MA-1

(11) TABLE-US-00002 TABLE 2 Characterization data of used macroalcohol. Mr, [g/mol] Hydrogenation level [%] OH functionality [%] MA-1 2,000 >99 >98

(12) Synthesis of Macromonomer MM-1

(13) In a 2 L stirred apparatus equipped with saber stirrer, air inlet tube, thermocouple with controller, heating mantle, column having a random packing of 3 mm wire spirals, vapor divider, top thermometer, reflux condenser and substrate cooler, 1000 g of the above-described macroalcohol are dissolved in methyl methacrylate (MMA) by stirring at 60° C. Added to the solution are 20 ppm of 2,2,6,6-tetramethylpiperidin-1-oxyl radical and 200 ppm of hydroquinone monomethyl ether. After heating to MMA reflux (bottom temperature about 110° C.) while passing air through for stabilization, about 20 mL of MMA are distilled off for azeotropic drying. After cooling to 95° C., LiOCH.sub.3 is added and the mixture is heated back to reflux. After the reaction time of about 1 hour, the top temperature has fallen to ˜64° C. because of methanol formation. The methanol/MMA azeotrope formed is distilled off constantly until a constant top temperature of about 100° C. is established again. At this temperature, the mixture is left to react for a further hour. For further workup, the bulk of MMA is drawn off under reduced pressure. Insoluble catalyst residues are removed by pressure filtration (Seitz T1000 depth filter).

(14) Table 3 summarizes the MMA and LiOCH.sub.3 amounts used for the synthesis of macromonomer MM-1

(15) TABLE-US-00003 TABLE 3 Macroalcohol, MMA and catalyst amounts for the transesterification of the macromonomer. Macromonomer Macroalcohol Amount MMA [g] Amount LiOCH.sub.3 [g] MM-1 MA-1 500 1.5

(16) Preparation of Amine-Containing Copolymer According to the Invention

(17) As described above, the polymer weight-average molecular weights were measured by gel permeation chromatography (GPC) calibrated using polymethylmethacrylate (PMMA) standards. Tetrahydrofuran (THF) is used as eluent.

(18) Example Polymer 1 (P1): Preparation of a Amine-Containing Copolymer According to the Invention

(19) 200 grams of Nexbase 3043, 11.34 grams of n-3-dimethylaminopropylmethacrylamid (DMAPMAA), 272.21 grams of lauryl methacrylate (C.sub.12-14 AMA, 5.53 grams of n-dodecyl mercaptan (n-DDM) 5.53 grams of 2-Ethylhexylthioglycolate (TGEH) were charged into 2 liter, 4-necked round bottom flask. The reaction mixture was stirred using a C-stirring rod, inerted with nitrogen, and heated to 90° C. Once the reaction mixture reached the setpoint temperature, 2.83 grams t-butylperoctoate was fed into the reactor over 2 hours. After 2 hours the mixture was heated up to 100° C. and after reaching the setpoint 1.42 grams of t-butylper-2-ethylhexanoate and 1.13 grams of tert-butylperpivalate were fed in one hour. Residual monomer was measured by gas chromatography to ensure good monomer conversion. The polymer obtained has a weight-average molecular weight M.sub.w of 10,500 g/mol (PMMA standard).

(20) Example Polymer 2 (P2): Preparation of an Amine-Containing Copolymer According to the Invention

(21) 276 grams of 100N oil (group II oil), 16 grams of methyl methacrylate, 13 grams of dimethylaminopropylmethacrylamide, 290 grams of C.sub.12-15 AMA, and 0.5 grams of n-dodecylmercaptan were charged into a 2-liter, 4-necked round bottom flask. The reaction mixture was stirred using a C-stirring rod, inerted with nitrogen, and heated to 110° C. Once the reaction mixture reached the setpoint temperature, 0.6 grams of tertbutyl-2-ethyleperoxyhexanoate were fed into the reactor over 3 hours. After the feed was complete, the reaction was allowed to stir for one hour. Residual monomer was measured by gas chromatography to ensure good monomer conversion. The polymer obtained has a weight-average molecular weight M.sub.w of 157,000 g/mol (PMMA standard).

(22) Example Polymer 3 (P3): Preparation of an Amine and Macromonomer-Containing Copolymer According to the Invention

(23) 85 grams of NB3020, 85 grams of Berylane 230SPP, 140 grams of macromonomer, 107 grams of butyl methacrylate, 28 grams of styrene, 13 grams of lauryl methacrylate, 8 grams of dimethylaminopropylmethacrylamide, and 1 grams of n-dodecylmercaptan were charged into a 2-liter, 4-necked round bottom flask. The reaction mixture was stirred using a C-stirring rod, inerted with nitrogen, and heated to 115° C. Once the reaction mixture reached the setpoint temperature, 0.9 grams of tertbutyl-2-ethyleperoxyhexanoate were fed into the reactor over 3 hours. 0.5 grams of 2,2-di-(tert-butylperoxy)-butane were added in 30 minutes and 3 hours after the previous feed. The reaction was allowed to stir for one hour, and then an additional 132 grams of NB3020 were added to the reactor and allowed to mix for 1 hour. The polymer obtained has a weight-average molecular weight M.sub.w of 260,000 g/mol (PMMA standard).

(24) For the examples P1, P2 and P3, the monomer components add up to 100%. The amount of initiator and chain transfer agent is given relative to the total amount of monomers. Table 4 below shows the monomer composition and reactants to prepare the polymers P1, P2 and P3, as well as their final characterization.

(25) TABLE-US-00004 TABLE 4 Composition, weight-average molecular weight and PDI of polymers according to the present invention C.sub.4 C.sub.1 C.sub.12-14- or C.sub.12-15 MM-1 Styrene AMA AMA AMA DMAPMA f.sub.branch Initiator CTA M.sub.w Ex [wt %] [wt %] [wt %] [wt %] [wt %] [wt %] — [%] [wt %] [g/mol] PDI P1 — — — — 96.0 4.0 — 1.9 3.9  10,500 1.61 C.sub.12-14 AMA P2 — — — 5.1 90.9 4.0 — 157,000 2.31 C.sub.12-15 AMA P3 38.49 11.01 42.0 0.24 4.88 3.38 1.8 0.75 0.40 260,000 2.85 C.sub.12-14 AMA

(26) Preparation of Polymeric-Inorganic Nanoparticle Concentrates According to the Invention

(27) Dispersion IE1:

(28) 4 g of IF-WS.sub.2 particles are given into a solution of 14 g NB3043 oil including 2 g of P1 while this mixture is treated with ultrasound (ultrasound processor UP400S with 400 Watt, 24 kHz with Ti-sonotrode). After the addition is finished the dispersion is treated for 120 minutes. The particle size distribution (measured in Tegosoft DEC oil using dynamic light scattering equipment, LA-950, Horiba Ltd., Japan) shows a d50 value of 54 nm.

(29) Dispersion IE2:

(30) 4 g of IF-WS.sub.2 particles are given into a solution of 13.6 g NB3043 oil including 2.2 g of P2 while this mixture is treated with ultrasound (ultrasound processor UP400S with 400 Watt, 24 kHz with Ti-sonotrode). After the addition is finished the dispersion is treated for 120 minutes. The particle size distribution (measured in Tegosoft DEC oil using dynamic light scattering equipment, LA-950, Horiba Ltd., Japan) shows a d50 value of 71 nm.

(31) Dispersion IE3 (with Ball Mill):

(32) The ball mill equipment (Netzsch Laboratory Mill Micro Series, 85% of milling chamber filled with 0.4 mm Y-stabilized ZrO.sub.2 balls) is pre-loaded with 245 g NB3043 oil and 35 g of P1 while the peristaltic pump is set to 80 rpm and the ball mill to 1000 rpm. Afterwards, 70 g of IF-WS.sub.2 particles are given into this solution. The ball mill is set to a rotation speed of 3500 rpm and the dispersion is treated until 1.0 kWh energy is introduced. The particle size distribution (measured in Tegosoft DEC oil using dynamic light scattering equipment, LA-950, Horiba Ltd., Japan) shows a d50 value of 47 nm.

(33) Dispersion IE4 (with Ball Mill):

(34) The ball mill equipment (Bachofen DynoMill, 70% of milling chamber is filled with 0.3-0.6 mm Ce-stabilized ZrO.sub.2 balls) is pre-loaded with 143.9 g NB3043 oil and 24.1 g of P2 while the ball mill is set to 3900 rpm. Afterwards, 42 g of IF-WS.sub.2 particles are given into this solution. The dispersion is treated until 2.8 kWh energy is introduced. The particle size distribution (measured in Tegosoft DEC oil using dynamic light scattering equipment, LA-950, Horiba Ltd., Japan) shows a d50 value of 48 nm.

(35) Dispersion IE5:

(36) 4 g of IF-WS.sub.2 particles are given into a solution of 13.6 g NB3043 oil including 2.4 g of P3 while this mixture is treated with ultrasound (ultrasound processor UP400S with 400 Watt, 24 kHz with Ti-sonotrode). After the addition is finished the dispersion is treated for 120 minutes. The particle size distribution (measured in Tegosoft DEC oil using dynamic light scattering equipment, LA-950, Horiba Ltd., Japan) shows a d50 value of 63 nm.

(37) Preparation of Polymeric-Inorganic Nanoparticle Concentrates as Comparative Example

(38) Dispersion CE1:

(39) 4 g of IF-WS.sub.2 particles are given into a solution of 14.8 g NB3043 oil including 1.2 g of ε-Caprolactam, while this mixture is treated with ultrasound (ultrasound processor UP400S with 400 Watt, 24 kHz with Ti-sonotrode) for 120 minutes, respectively. The particle size distribution (measured in Tegosoft DEC oil using dynamic light scattering equipment, LA-950, Horiba Ltd., Japan) shows a d50 value of 1,427 nm.

(40) Dispersion CE2:

(41) 4 g of IF-WS.sub.2 particles are given into a solution of 14.8 g NB3043 oil including 1.2 g of OCTMO, while this mixture is treated with ultrasound (ultrasound processor UP400S with 400 Watt, 24 kHz with Ti-sonotrode) for 120 minutes, respectively. The particle size distribution (measured in Tegosoft DEC oil using dynamic light scattering equipment, LA-950, Horiba Ltd., Japan) shows a d50 value of 432 nm.

(42) The table 5 below summarizes the compositions of the inventive dispersions (IE) according to the invention and the comparative dispersions (CE). The listed weight percentages are based on the total weight of the different compositions.

(43) TABLE-US-00005 TABLE 5 Comparison of dispersions according the present invention Nanoparticles Polymer Nexbase ® (A) IF-WS.sub.2 (B) content Dispersant 3043 in Example in wt % Dispersant in wt % in wt % wt %  IE1 20 P1 6 10 70  IE2 20 P2 6 11.1 68.9  IE3 20 P1 6 10 70  IE4 20 P2 6 11.1 68.9  IE5 20 P3 6 12 68 CE1 20 ε- — 6 74 Caprolactam CE2 20 OCTMO — 6 74

(44) Dynamic Light Scattering (DLS)

(45) The particle size distribution was measured in Tegosoft DEC oil using the dynamic light scattering equipment LB-500 produced by Horiba Ltd.

(46) Dynamic light scattering (DLS) is a technique in physics that can be used to determine the size distribution profile of small particles in suspension or polymers in solution. This equipment can be used to measure the particle size of dispersed material (inorganic nanoparticles or polymeric spheres, e.g.) in the range from 3 nm to 6 μm. The measurement is based on the Brownian motion of the particles within the medium and the scattering of incident laser light because of a difference in refraction index of liquid and solid material.

(47) The resulting value is the hydrodynamic diameter of the particle's corresponding sphere. The values d50, d90 and d99 are common standards for discussion, as these describe the hydrodynamic diameter of the particle below which 50%, 90% or 99% of the particles are within the particle size distribution. The lower these values, the better the particle dispersion. Monitoring these values can give a clue about the particle dispersion stability. If the values increase tremendously, the particles are not stabilized enough and may tend to agglomerate and sediment over time resulting in a lack of stability. Depending on the viscosity of the medium, it can be stated, that a d99 value of <500 nm (e.g. for Nexbase base oil) is an indication for a stable dispersion as the particles are held in abeyance over time.

(48) Determination of Weld and Friction Properties of the Lubricating Composition According to the Invention

(49) Lubricating formulations were prepared according to weight ratios shown in Table 6 below and their friction and weld performances were tested using two methods described below. The listed weight percentages are based on the total weight of the different formulations.

(50) For the sake of comparison lubricating formulations are always compared based on the same content of intercalation compound. Therefore, formulations named with “−1” correspond to formulations having an intercalation compound concentration of 0.1 wt %, based on the total weight of lubricating formulation. Similarly “−2” corresponds to a concentration of 0.5 wt % and “−3” corresponds to a concentration of 1 wt %. The formulations named with “a” correspond to formulations prepared with a fully formulated oil composition according ISO VG 68. The formulations named with “b” correspond to formulations prepared with Nexbase® 3043.

(51) Fully formulated oil composition according ISO VG 68: 79.25 wt % Nexbase® 3060 (Base oil) 17.4 wt % VISCOBASE® 5-220 (Base oil) 0.7 wt % PPD 2.65 wt % Afton HiTec® 307 (DI package) +0.2 wt % VISCOPLEX® 14-520 (defoamer)

(52) TABLE-US-00006 TABLE 6 Lubricating formulations Particle Inventive examples Comparative examples concentration in Fully formulated Dispersion Dispersion Dispersion Dispersion Dispersion formulation oil ISO VG 68 IEl IE2 IE4 CE1 CE2 Formulation IE1-1a 0.1 wt % 99.5 wt % 0.5 wt % Formulation IE1-2a 0.5 wt % 97.5 wt % 2.5 wt % Formulation IE2-3a   1 wt %   95 wt % 5.0 wt % Formulation IE4-3a   1 wt %   95 wt % 5.0 wt % Formulation CE1-3a   1 wt %   95 wt % 5.0 wt % Formulation CE2-3a   1 wt %   95 wt % 5.0 wt %

(53) Determination of the Improvement in Weld (Extreme Pressure) According to Four Ball Weld Test

(54) Four ball weld tests were performed according to DIN 51350 part 2 (results see FIG. 2)

(55) Table 7 summarizes the results of the 4 ball weld test.

(56) The reference base oil mixture, fully formulated oil ISO VG 68 welds at an average weld load of 5000 N.

(57) Comparative Example Formulation CE1-3a represents a formulation of fully formulated oil ISO VG 68 with addition of 5 wt % of dispersion CE1 (corresponding to 1 wt % intercalation compound). Weld load was found to be 4900 N.

(58) Comparative Example Formulation CE2-3a represents a formulation of fully formulated oil ISO VG 68 with addition of 5 wt % of dispersion CE2 (corresponding to 1 wt % intercalation compound). Weld load was found to be 3800 N.

(59) Inventive Examples IE1, IE2 and IE4 contain the polymeric inorganic nanoparticles synthesized using Polymer P1 or P2 and IF-WS.sub.2. The particles are well dispersed and stable in the formulation.

(60) Inventive Example Formulation IE1-1a represents a formulation of fully formulated oil ISO VG 68 with addition of 0.5 wt % of dispersion IE1 (corresponding to 0.1 wt % intercalation compound). Weld load was found to be 7250 N.

(61) The measured weld load is increased by 45% compared to the fully formulated oil ISO VG 68 reference.

(62) Inventive Example Formulation IE1-2a represents a formulation of fully formulated oil ISO VG 68 with addition of 2.5 wt % of dispersion IE1 (corresponding to 0.5 wt % intercalation compound). Weld load was found to be 8250 N.

(63) The measured weld load is increased by 65% compared to the fully formulated oil ISO VG 68 reference.

(64) Inventive Example Formulation IE2-3a represents a formulation of fully formulated oil ISO VG 68 with addition of 5 wt % of dispersion IE2 (corresponding to 1 wt % intercalation compound). Weld load was found to be 7000 N.

(65) The measured weld load is increased by 40% compared to the fully formulated oil ISO VG 68 reference.

(66) Inventive Example Formulation IE4-3a represents a formulation of fully formulated oil ISO VG 68 with addition of 5 wt % of dispersion IE4 (corresponding to 1 wt % intercalation compound). Weld load was found to be 8750 N.

(67) The measured weld load is increased by 75% compared to the fully formulated oil ISO VG 68 reference.

(68) TABLE-US-00007 TABLE 7 Results of the weld load tests Particle Maximal concentration weld Example in formulation load in N Formulation IE1-1a 0.1 wt % 7250 Formulation IE1-2a 0.5 wt % 7000 Formulation IE2-3a   1 wt % 8250 Formulation IE4-3a   1 wt % 8750 Formulation CE1-3a   1 wt % 4900 Formulation CE2-3a   1 wt % 3800

(69) The higher the weld load, the better the extreme pressure performance. The reference oil formulation reaches a weld load of 5000 N. We can see the clear proof that the addition of polymeric-inorganic nanoparticle composition according to the present invention into a lubricating oil formulation improves the weld performance of the lubricating oil drastically. In comparison, the state-of-art dispersions (CE1-CE2) have lower weld load values, even lower than the reference oil formulation without any particles. The above experimental results show that the polymeric-inorganic nanoparticle compositions of the invention results in stable intercalation compound containing lubricating oil compositions, while maintaining or even improving the weld performance of the treated lubricating oil compositions. This result is surprising because the stability of lubricating oils with nanoparticles is limited over time as shown by the comparative examples with lower weld load values as the non-treated reference oil composition.

(70) Determination of Shear Stability for the Inventive Dispersion IE3

(71) Shear stability test was performed according to DIN 51350 part 6

(72) Inventive Example contains the polymeric inorganic nanoparticles synthesized using Polymer P1 and IF-WS.sub.2. The particles are well dispersed and stable in the formulation.

(73) Inventive Example Formulation IE3 with 0.25 wt % intercalation compound content represents a formulation of fully formulated oil ISO VG 68 with addition of 1.25 wt % of dispersion IE3. This formulation according to the invention is still stable after shear test.

(74) Determination of the Reduction in Friction Via Mini Traction Machine

(75) The coefficient of friction was measured using a Mini traction machine named MTM2 from PCS Instruments following the test method described in Table 4 below. SRR refers to the Sliding Roll Ratio. This parameter was maintained constant during the 2 hours test and is defined as (U.sub.Ball−U.sub.Disc)/U wherein (U.sub.Ball−U.sub.Disc) represents the sliding speed and U the entrainment speed, given by U=(U.sub.Ball+U.sub.Disc)/2. Stribeck curves for each sample were measured according to protocol in Table 8.

(76) TABLE-US-00008 TABLE 8 Protocol to measure the Stribeck curves Method 1 Test Rig MTM 2 from PCS Instruments Disc Highly polished stainless Steel AISI 52100  Disc diameter 46 mm Ball Highly polished stainless Steel AISI 52100 Ball diameter 19.05 mm Speed 5-2,500 mm/s Temperature 100° C. Load 30N SRR 50%

(77) According to MTM Method 1, the friction coefficient was recorded over the complete range of speed for each blend and a Stribeck curve is obtained. The friction tests were performed according to these conditions for the formulations listed in Table 9 and results thereof are disclosed in Table 10 below. The listed weight percentages are based on the total weight of the different formulations.

(78) TABLE-US-00009 TABLE 9 Formulations according to the invention Particle concentration in Nexbase ® Dispersion Dispersion Dispersion formulation 3043 IE4 IE5 CE1 Formulation IE4-3b 1 wt % 95 wt % 5.0 wt % Formulation IE5-3b 1 wt % 95 wt % 5.0 wt % Formulation CE1-3b 1 wt % 95 wt % 5.0 wt %

(79) To express in % the friction reduction, a quantifiable result can be expressed as a number and is obtained by integration of the friction value curves using the obtained corresponding Stribeck curves in the range of sliding speed 5 mm/s-60 mm/s using the trapezoidal rule. The area corresponds to the “total friction” over the selected speed regime. The smaller the area, the greater the friction-reducing effect of the product examined. The percentage friction reductions were calculated by using the values of the reference base oil Nexbase® 3043, which generates an area of friction of 6.32 mm/s. Positive values indicate a decrease of friction coefficients. Values in relation to the reference oil are compiled in the table 10 (see FIG. 1).

(80) TABLE-US-00010 TABLE 10 Friction reduction in boundary regime for the formulations according to the invention compared to base oil Friction area Reduction of Example from 5-60 mm/s Friction in % Nexbase ® 3043 6.32 reference Formulation IE4-3b 2.42 62 Formulation IE5-3b 2.37 62.5 Formulation CE1-3b 4.55 28

(81) The above experimental results show that the polymeric-inorganic nanoparticle compositions of the invention are stable in the lubricating oil composition over time and show great anti-friction performance in comparison to the oil formulation of the art. Indeed, the results of the calculated total friction in the range of sliding speed 5 mm/s-60 mm/s clearly show that the inventive examples IE4 and IE5 have a much better effect with regard to the reduction in friction than the corresponding comparative example and reference Nexbase® 3043 oil. Nexbase® 3043 is the reference base oil. This result is surprising because the stability of lubricating oils with nanoparticles is limited over time as shown by the comparative example with lower friction reduction value.

(82) The results obtained were not foreseeable from the available documentation of the state of the art. There it is referred to the intact onion shape which can roll out over the surface during tribo contact in order to reduce friction through gliding effects between the two surfaces moving against each other. Surprisingly, the polymeric-inorganic nanoparticles obtained by ball milling the dispersion according to the present invention provide improved anti-friction properties to the lubricant oil compositions, in which they are mixed. It has been demonstrated that the chemically modified nanoparticles of the invention have a positive influence on friction behaviors, while maintaining excellent stability over a long period of time in the lubricating oil.