HIGH TEMPERATURE LUBRICANT

Abstract

The invention relates to a food-compatible high-temperature lubricant, more particularly a high-temperature oil and a high-temperature grease, comprising the following components: a) at least one oil selected from a trimellitic ester or a mixture of different trimellitic esters, alkylaromatics, preferably an aliphatically substituted naphthalene, or estolides; b) a hydrogenated or fully hydrogenated polyisobutylene or a mixture of hydrogenated or fully hydrogenated polyisobutylene; and c) additives individually or in combination.

In the case of the high-temperature grease, a thickener is added.

Claims

1. High-temperature oil comprising a) 93.9 to 45 wt % of at least one oil selected from the group consisting of alkylaromatics, estolides, trimellitic esters, or a mixture of different trimellitic esters wherein the alcohol group of the ester is a linear or branched alkyl group having 8 to 16 carbon atoms; b) 6 to 45 wt % of a polymer, specifically a hydrogenated or fully hydrogenated polyisobutylene, or a mixture of hydrogenated or fully hydrogenated polyisobutylene; c) 0.1 to 10 wt % of additives, individually or in combination, selected from the group consisting of anticorrosion additives, antioxidants, antiwear additives, UV stabilizers, inorganic or organic solid lubricants.

2. High-temperature oil according to claim 1, wherein the oil component comprises as a further oil a compound selected from the group consisting of mineral oil, aliphatic carboxylic and dicarboxylic esters, fatty acid triglycerides, pyromellitic esters, diphenyl ethers, phloroglucinol esters and/or poly-alpha-olefins, alpha-olefin copolymers.

3. High-temperature grease comprising a) 91.9 to 25 wt % of at least one oil selected from the group consisting of alkylaromatics, estolides, trimellitic esters, or a mixture of different trimellitic esters wherein the alcohol group of the ester is a linear or branched alkyl group having 8 to 16 carbon atoms; b) 6 to 45 wt % of a polymer, selected from the group consisting of a hydrogenated or fully hydrogenated polyisobutylene or a mixture of hydrogenated or fully hydrogenated polyisobutylene; c) 0.1 to 10 wt % of additives, individually or in combination, selected from the group consisting of anticorrosion additives, antioxidants, antiwear additives, UV stabilizers, inorganic or organic solid lubricants, and d) 2 to 20 wt % of thickener.

4. High-temperature grease according to claim 3, wherein the oil component comprises as a further oil a compound selected from the group consisting of mineral oil, aliphatic carboxylic and dicarboxylic esters, fatty acid triglycerides, pyromellitic esters, diphenyl ethers, phloroglucinol esters and/or poly-alpha-olefins, alpha-olefin copolymers.

5. High-temperature grease according to claim 3, wherein the thickener is selected from the group consisting of urea, Al complex soaps, simple metal soaps of the elements of the first and second main groups of the Periodic Table, metal complex soaps of the elements of the first and second main groups of the Periodic Table, bentonites, sulfonates, silicates, Aerosil, polyimides, PTFE or a mixture of the aforesaid thickeners.

6. High-temperature oil or high-temperature grease according to claim 1, wherein the alkylaromatic compound is an aliphatically substituted naphthalene.

7. Use of the high-temperature oil according to claim 1 for the lubrication of roller bearings and plain bearings, in vehicle technology, in conveying technology, in mechanical engineering, in office technology, and in industrial plants and machines, but also in the areas of household appliances, of consumer electronics, and for the lubrication of chains, chain rollers, and belts of continuous presses.

8. High-temperature oil or high-temperature grease according to claim 3, wherein the alkylaromatic compound is an aliphatically substituted naphthalene.

9. Use of the high-temperature grease according to claim 3 for the lubrication of roller bearings and plain bearings, in vehicle technology, in conveying technology, in mechanical engineering, in office technology, and in industrial plants and machines, but also in the areas of household appliances, of consumer electronics, and for the lubrication of chains, chain rollers, and belts of continuous presses.

Description

EXAMPLES 1 TO 2

[0068] Production of a High-Temperature Oil of the Invention

[0069] Estolides or aliphatically substituted naphthalenes are charged to a stirred vessel. At 100° C., with stirring, the polyisobutylene and optionally a further oil are added. The mixture is subsequently stirred for 1 hour in order to give a homogeneous mixture. The antiwear agents and the antioxidant are added to the vessel with stirring at 60° C. After about 1 hour, the completed oil can be dispensed into the intended containers.

Composition of the High-Temperature Oils

[0070]

TABLE-US-00001 TABLE 1 Inventive Comparative example 1 example 1 Trimellitate 0.0 63.0 Estolide 1 44.0 0.0 Estolide 2 19.0 0.0 Hydrogenated PIB 30.4 30.4 Aminic antioxidant 2.0 2.0 Phenolic antioxidant 1.0 1.0 EP/WA antiwear agent 3.5 3.5 Anticorrosion agent 0.1 0.1 Dissolubility of residues Very good (4) Very good (4)

TABLE-US-00002 TABLE 2 Inventive Comparative example 2 example 2 Trimellitate 1 0 76.0 Alkylated naphthalene 76.0 0.0 Hydrogenated PIB 20.0 20.0 Aminic antioxidant 4.0 4.0 Dissolubility of residues Very good (4) Very good (4)

[0071] The base data of the oil examples can be taken from table 3.

TABLE-US-00003 TABLE 3 Inventive Comparative Inventive Comparative Formula example 1 example 1 example 2 example 2 Eisenmann test [250° C., 72 h] Dissolubility 4 4 4 4 Base data Flash point (° C.) >250 >250 >250 >250 kin. V40 280.0 270.0 300.0 140.5 kin. V100 29.00 25.0 25.00 16.13 VI 137 120.0 105 121

[0072] Furthermore, the abrasion behavior of the oils was measured in SRV in a method based on DIN 51834-2, and the loss on evaporation was measured in dynamic TGA. The results are shown in tables 4 and 5 and are reproduced graphically in FIGS. 1 and 2.

TABLE-US-00004 TABLE 4 Inventive Comparative Inventive Comparative SRV TST (250 N) example 1 example 1 example 2 example 2  50-120° C. 0.116 0.112 0.156 0.091 120-140° C. 0.111 0.127 0.155 0.091 140-160° C. 0.105 0.141 0.158 0.128 160-180° C. 0.1 0.145 0.163 0.139 180-200° C. 0.095 0.143 0.171 0.165 200-210° C. 0.08 0.137 0.177 0.194 210-220° C. 0.086 0.132 0.175 0.206 220-230° C. 0.085 0.129 0.179 0.208 230-240° C. 0.087 0.126 0.185 0.208 240-250° C. 0.091 0.121 0.189 0.206 250° C. isotherm 0.093 0.118 0.186 0.201

TABLE-US-00005 TABLE 5 Inventive Comparative Inventive Comparative TGA dynamic example 1 example 1 example 2 example 2 120° C. 0.1 0.1 0.1 0.1 140° C. 0.3 0.2 0.3 0.2 160° C. 0.6 0.5 0.4 0.4 180° C. 1 0.9 0.9 0.7 200° C. 1.7 1.4 1.8 1.2 220° C. 2.8 2.3 3.6 2.2 240° C. 4.6 3.7 6.6 3.7 260° C. 7.7 5.9 11.7 6.3

Examples 3 to 8

[0073] Production of a High-Temperature Grease of the Invention

[0074] The base oil is charged to a stirred vessel. At 100° C., with stirring, the polyisobutylene and optionally a further oil and the thickener are added.

[0075] The thickener is formed by in situ reaction of the reactants used in the base oil. The mixture is subsequently heated to 150° C. to 210° C., stirred for a number of hours and cooled again. In the cooling process, at approximately 60° C., the required antiwear agents, antioxidants, and anticorrosion agents are added. A homogeneous grease mixture is obtained by the concluding homogenization step via roller, colloid mill or the Gaulin.

[0076] The compositions of the high-temperature greases are shown in table 6.

TABLE-US-00006 TABLE 6 Li Li Li complex complex complex Diurea Diurea Diurea Type Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Trimellitic ester 60 0 0 65.2 0 0 [wt %] Estolide [wt %] 0 0 56 0 0 65.2 Alkylated 0 64 0 0 65.2 0 naphthalene [wt %] Fully 26 25 25 25 25 25 hydrogenated polyisobutylene [wt %] Additive 4 1 4 1 1 1 package [wt %] Thickener 10 10 15.0 8.8 8.8 8.8 concentration [wt %]

[0077] The thickeners used in examples 3 to 8 are as follows:

[0078] example 3: LiOH, 12-hydroxystearic acid, azelaic acid

[0079] example 4: LiOH, 12-hydroxystearic acid, azelaic acid

[0080] example 5: LiOH, 12-hydroxystearic acid, azelaic acid

[0081] example 6: diurea; methylenediphenyl diisocyanate (MDI), octylamine, oleylamine

[0082] example 7: diurea; MDI, octylamine, oleylamine

[0083] example 8: diurea; MDI, octylamine, oleylamine

[0084] The general characteristics of grease specimens 3 to 8 are shown in table 7.

TABLE-US-00007 TABLE 7 Characteristics Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Cone penetration 284 283 278 232 232 300 after 60 DT [DIN ISO 2137] Cone penetration 324 319 319 254 254 338 after 100 000 DT [DIN ISO 2137] Dropping point >300 >300 >300 >300 280 292 [C. °] [DIN ISO 2176] Flow pressure >2000 275 284 575 525 <1400 −20° C.; [mbar] [DIN 51805] Flow pressure >2000 425 675 <1400 <1400 <1400 −30° C.; [mbar] [DIN 51805] Oil dep. 3.80 3 1.70 1.2 0.10 5.60 40° C./168 h; [wt %] [DIN 51817] Oil dep. 7.4 7.5 2.50 0.20 0.30 5.00 150° C./30 h; [wt %] [FTMS 761 C] Loss on 2 5.3 2.50 1.6 3.5 2.1 evaporation 150° C./24° C. [DIN 58397 Part 1] Water resistance, 1 2 1.00 0 1 1 static [DIN 51807]

[0085] The losses on evaporation of the various grease specimens at 150° C. after 30 h are between 2% and 5%, thereby emphasizing the very good thermal stability of these grease designs.

[0086] A critical influence on the lubricating activity of a grease is possessed by the oil deposition. Here it should be ensured that first of all the oil deposition is not too high and that the oil runs from the bearing and therefore is no longer available to the tribological system, and on the other hand that no oil deposition is observed with loss of the lubricating activity of the grease. The oil deposition ought ideally to be between 0.5 and 8 wt %, to allow an optimum lubricating film to be formed in the bearing.

[0087] The greases of the examples were subjected to a DIN 51 821 FE 9 roller bearing test, which determines the lifetime of the greases under investigation and determines the upper service temperature of lubricating greases in roller bearings at moderate speeds and moderate axial loads.

[0088] The greases investigated and the results of the L10 and L50 values are shown in table 8.

TABLE-US-00008 TABLE 8 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 FE 9 [180° C., 6000 1/min, 1500 N] L 50 (h) 249 >100 207 146 >100 >100 L 10 (h) 169 >50 138 72 >50 >50

[0089] Table 8 shows that the running times, as a result of the use of PIB in conjunction with various base oils, exhibit long running times and are therefore suitable for high application temperatures in long-term operation.

[0090] Furthermore, the noise characteristics of the greases were measured in accordance with SKF Be Quiet.sup.+ for examples 3 to 8. The results are reported in table 9.

TABLE-US-00009 TABLE 9 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Noise testing GN4 GN3 GN3 GN2 GN3 GN4 [BeQuiet.sup.+ SKF]

[0091] The noise characteristics of the various grease formulations are influenced very positively by the use of the fully hydrogenated polyisobutylene. With the exception of example 6, good to very good noise qualities can be achieved.

[0092] The properties of the grease of example 3, for which fully hydrogenated PIB was used, were then compared with a grease (comparative example 3) containing a PIB in which double bonds were still present, in other words a non-fully hydrogenated PIB.

[0093] The rest of the composition of the grease of comparative example 3 corresponded to that of inventive example 3.

TABLE-US-00010 TABLE 10 Inventive Comparative ex. 3 ex. 3 FE 9 [180° C., 6000 l/min, 1500 N] L 50 (h) 249 126 L 10 (h) 169 72 Noise testing [BeQuiet + SKF] GN4 GN1 Loss on evaporation [DIN ISO 58397] 4.3 5.1 170° C./24 h Loss on evaporation [DIN ISO 58397] 6.9 7.4 180° C./24 h Cone penetration after 60 DT 284 301 [DIN ISO 2137] Cone penetration after 100 000 DT 324 356 [DIN ISO 2137] Corrosive action of lubricants on copper 1a n.s. [DIN ISO 51811] 150° C./24 h Oil deposition 150° C./30 h; [wt %] [ASTM 7.4 8.4 D 6184] Oil deposition 150° C./30 h; [wt %] [ASTM D 17.9 14.7 6184] Oil deposition 168° C./40 h; [wt %] 3.8 6.5 [DIN 51817] Testing of lubricant greases for 0 n.s. corrosion prevention properties [DIN 51801/ISO 11007] Dropping point [C.°] >300 295.0 [DIN ISO 2176] Loss on evaporation 150° C./24° C. 2 2.4 [DIN 58397 Part 1] Water resistance, static [DIN 51807] 90° C. 0 n.s.

[0094] The comparison of the greases with fully hydrogenated PIB and non-fully hydrogenated PIB in table 10 shows that the grease of inventive example 3 exhibits twice the running time in the FE9 test, and has lower losses on evaporation and significantly better noise characteristics.

[0095] For verifying the advantageous properties of the oil containing fully hydrogenated PIB, it was compared with an oil containing a partially hydrogenated PIB. Table 11 shows the results.

TABLE-US-00011 TABLE 11 Oil 1 Oil 2 Specimen Estolide 1 32.966 wt % 32.966 wt % Estolide 2 26.874 wt % 26.874 wt % Fully hydrogenated PIB  33.65 wt % — Partially hydrogenated PIB —  33.65 wt % Antioxidant    3 wt %    3 wt % AW   3.5 wt %   3.5 wt % Anticorrosion agent  0.01 wt %  0.01 wt % Test methods V40 (mm.sup.2/s) 277.8 277.6 V100 (mm.sup.2/s) 28.28 27.90 Viscosity index 136 134 Eisenmann test 72 h/250° C. residue (%) 6.6 8.0 Eisenmann test 72 h/250° C. dissolubility 4 1 Eisenmann test 120 h/220° C. residue (%) 13.8 19.2 Eisenmann test 120 h/220° C. dissolubility 3 1 HTS chain test bench 220° C./2600 N/2.sub.m/s 15 13 (h) 4 = residue highly dissoluble after complete evaporation 3 = residue readily dissoluble after complete evaporation 2 = residue partially dissoluble after complete evaporation 1 = residue not dissoluble after complete evaporation

[0096] Table 11 shows that there are distinct differences in connection with the use of fully hydrogenated and partially hydrogenated PIB. Thus the dissolution of the residue on the basis of the partially hydrogenated PIV is no longer possible, whereas the oil with the fully hydrogenated PIB exhibits very good redissolution properties.