THERMOPLASTIC COMPOSITION

Abstract

Lubricant grease compositions comprising a silicone base stock oil having a kinematic viscosity of from 20,000 to 100,000 mm.sup.2/s at 25° C., a metal salt of a fatty acid wherein the metal is selected from the group of lithium, calcium, aluminium, barium titanium, zinc, magnesium and/or sodium; and a suitable anti-wear additive.

Claims

1. A lubricating grease composition comprising (a) 65 to 89.9% by weight of a silicone base stock oil having a kinematic viscosity of from 20,000 to 100,000 mm.sup.2/s at 25° C.; (b) 10 to 35% by weight of a metal salt of a fatty acid wherein the metal is selected from the group of lithium, calcium, aluminium, barium titanium, zinc, magnesium and/or sodium; and (c) 0.1 to 2% by weight of a suitable anti-wear additive.

2. A lubricant composition according to claim 1 where (a) is selected from a silicone lubricant base stock oil of Group V, as per the API classification of lubricant base oils or mixtures or greases thereof.

3. A lubricant composition according to claim 1 where (a) is selected from a silicone lubricant base stock oil trialkyl terminated polydiethylsiloxane, trialkyl silyl terminated polydimethylsiloxane, trialkyl silyl terminated polydimethylmethylalkylsiloxane, or trialkyl silyl terminated polymethylalkylsiloxane.

4. A lubricant composition according to claim 1 wherein component (b) comprises one or more of the lithium monocarboxylic fatty acids or lithium hydroxymonocarboxylic fatty acids, calcium monocarboxylic fatty acids or calcium hydroxymonocarboxylic fatty acids, aluminium monocarboxylic fatty acids or aluminium hydroxymonocarboxylic fatty acids barium monocarboxylic fatty acids or barium hydroxymonocarboxylic fatty acids and titanium monocarboxylic fatty acids or titanium hydroxymonocarboxylic fatty acids zinc monocarboxylic fatty acids or zinc hydroxymonocarboxylic fatty acids, magnesium monocarboxylic fatty acids or magnesium hydroxymonocarboxylic fatty acids and/or sodium monocarboxylic fatty acids.

5. A lubricant composition according to claim 1 wherein component (b) comprises one or more of, calcium, aluminium, barium and titanium, zinc, magnesium and/or sodium salts of fatty acids derived from animal oils or from vegetable oils.

6. A lubricant composition according to claim 1 wherein component (b) comprises the metal salts of one or more of lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, myristoleic acid, palmitoleic acid, oleic acid, or a linoleic acid.

7. A lubricant composition according to claim 1 wherein component (b) comprise lithium salts of 12-hydroxystearic acid, 14-hydroxystearic acid, 16-hydroxystearic acid, 6-hydroxystearic acid, or 9,10-hydroxystearic acid.

8. A lubricant composition according to claim 1 wherein component (c) comprise zinc dithiophosphate, organic polysulphides, phosphates, amine salt of sulphurized dibutyl hydrogen phosphate, dialkyldithiophosphates dithiocarbamates dihydrocarbyl phosphate; tricresyl phosphate sulphurized olefins, and sulphurized fatty acid esters.

9. A lubricant composition according to claim 1 wherein the composition may comprise up to 5% by weight of dry lubricant.

10. A lubricant composition according to claim 9 wherein the dry lubricant may include one or more of graphite, molybdenum disulphide, boron nitride, talc, polytetrafluoroethylene (PTFE), calcium fluoride, cerium fluoride, or tungsten disulfide.

11. A lubricant composition according to claim 1 wherein the composition additionally comprises one or more additives selected from friction modifiers, extreme pressure additives, seal swelling agents, rust and corrosion inhibitors, Viscosity Index improvers, pour point depressants, anti-oxidants, free-radical scavengers, hydroperoxide decomposers, metal passivators, surface active agents such as detergents, emulsifiers, demulsifiers, defoamants, compatibilizers, dispersants, deposit control additives, film forming additives, tackifiers, antimicrobials, additives for biodegradable lubricants, haze inhibitors, chromophores, and limited slip additives and mixtures thereof.

12. A lubricant composition according to claim 11 wherein each of the one or more additive(s) may be used at a level of from 0.01 to 10 wt % based on the total weight of the composition.

13. A method of lubricating, comprising the steps of: applying a Use of a lubricant composition in accordance with claim 1 to bearings in electric motors, wheel bearings, bearings in household appliances, machine tools or aircraft accessories, small gear drives, slow speed sliding applications, constant velocity joints, ball joints, alternators, cooling fans, ball screws, chucks, linear guides and machine tools, and dampen HiFi systems.

14. (canceled)

15. The method according to claim 13, wherein the lubricant composition is able to lubricate at temperatures below −30° C.

Description

EXAMPLES

[0082] The following formulation identified as Example 1 is a composition in accordance with composition herein and which was used throughout the following examples.

TABLE-US-00001 TABLE 1 Composition of Example 1 (Ex. 1) % by weight of the Component Function total composition Trimethylsiloxy terminated Base Oil 78.5 polydimethyl siloxane 30,000 mm.sup.2/s at 25° C. (ISO 3104: 1994(en)) 12-Hydroxy Lithium stearate Single Soap 21.0 Thickener Anti-wear and -corrosion 0.5 additive

[0083] The following table shows the test results of common industrial standard tests for greases, which tests were undertaken on the composition identified as Example 1 above and depict .describe grease properties in general for said Example 1. The ingredients were mixed together.

TABLE-US-00002 TABLE 2 Physical Properties of Ex. 1 grease composition Test Standard Example 1 Nature Pasty, medium uninterrupted Odour clearly noticeable, not disrupted Colour DIN 6167 (1980-01) white to light grey Consistency class DIN 51818 (1981-12) 0 to 1 Density DIN 51757 - 2011-01 0.96 Drop point (° C.) IP396-02 221 Unworked penetration (¼ cone) DIN ISO 2137: 2007 317 (0.1 mm) Worked penetration (60 DIN ISO 2137: 2007 319 strokes) (0.1 mm) Oil separation after 168 DIN 51817: 2014-08 0.12 hours at 40° C. (weight-%) EMCOR-Corrosion-Protection DIN 51808: 2015-11 0 (distilled, water 168 h) (Degree of corrosion) Flow pressure at −40° C. (Pa) DIN 518051974 - 08 15,000 Water resistance (+90° C.) DIN 51807-1: 1979 - 04 1-90

[0084] The difference between the static and dynamic coefficients of friction of Example 1 (high viscosity) were then compared with those of a variety of comparative lubricant grease compositions all of which contained much lower viscosity silicone base stock oils (<1000 mm.sup.2/s) at 25° C. following the general method described in ISO 3104: 1994(en) having their compositions identified in Tables 3 to 7.

TABLE-US-00003 TABLE 3 composition of Comparative. 1 (Comp. 1) Components Function % wt. trimethylsiloxy terminated Base oil 78.5 Polydimethyl siloxane, 200 mm.sup.2/s at 25° C. 12-Hydroxy Lithium stearate Single soap thickener 21 18% Triazole derivative 82% VCF Anti-wear and -corrosion 0.5 additive

TABLE-US-00004 TABLE 4 composition of Comparative. 2 (Comp. 2) Components Function % wt. Trimethylsiloxy terminated Base oil 78.6 polydimethylsiloxane 350 mm.sup.2/s at 25° C. 12-Hydroxy Lithium stearate Complex thickener 14.7 component Nonanedioic Acid, Di Lithium Salt Complex thickener 5.8 component Anti-corrosion additive Anti-corrosion additive 0.9

TABLE-US-00005 TABLE 5 composition of Comparative. 3 (Comp. 3) Components Function % wt. Trimethylsiloxy terminated phenylmethyl Base oil 84.6 siloxane 500 mm.sup.2/s at 25° C. in which Ph:Me ratio 7:1 12-Hydroxy Lithium stearate Complex thickener 7.2 component Nonanedioic Acid, Di Lithium Salt Complex thickener 2.7 component Polytetrafluoroethylene (PTFE) Solid lubricant 4.6 additive 1,2-Dihydro-2,2,4-Trimethylquinoline Anti-oxidant additive 0.9 Homopolymer

TABLE-US-00006 TABLE 6 composition of Comparative. 4 (Comp. 4) Components Function % wt. Trimethylsiloxy terminated phenylmethyl Base oil 81.8 siloxane 100 mm.sup.2/s at 25° C. in which Ph:Me ratio 5:1 Lithium stearate Single soap 18.2 thickener

TABLE-US-00007 TABLE 7 composition of Comparative. 5 (Comp. 5) Components Function % wt. Trimethylsiloxy terminated Base oil 83.0 phenylmethyl siloxane 125 mm.sup.2/s at 25° C. in which Ph:Me ratio 1:1 Lithium stearate Single soap 17.0 thickener

[0085] Example. 1 and the above comparatives were analysed to determine the difference between their respective dynamic and static coefficients of friction using a stick-slip tester from AKE-technologies GmbH called Anti-Knarz (noise) Machine.

[0086] The Anti-Knarz (noise) Machine is sensitive enough to measure the static and dynamic friction coefficient by way of a ball plate tribometer-system. The tester was used for internal pre-test selection of the grease candidate with lowest friction level of static and dynamic friction coefficient and the smallest difference of both. The tests were run using the parameters:

Specimen: 12.7 mm POM Ball/S-36 Q-Panel

[0087] Speed: 0.5 mm/sec

Load: 30 Newton

[0088] Cycles: 1000 (measured every 10 cycles)
Running distance: 5 mm
Duration of measurement: 20 sec
The results are depicted in Table 8 below.

TABLE-US-00008 TABLE 8 comparisons of Coefficients of friction and their respective differences. Friction Coefficient μ Difference Product Run μ static μ dynamic μ stat. − μ dyn. Ex. 1 1 0.15 0.11 0.040 Ex. 1 2 0.15 0.11 0.040 Ex. 1 Average 0.15 0.11 0.040 Comp. 1 1 0.18 0.13 0.050 Comp. 1 2 0.18 0.13 0.050 Comp. 1 Average 0.18 0.13 0.050 Comp. 2 1 0.15 0.11 0.040 Comp. 2 2 0.14 0.11 0.030 Comp. 2 Average 0.145 0.11 0.035 Comp. 3 1 0.28 0.21 0.070 Comp. 3 2 0.29 0.23 0.060 Comp. 3 Average 0.285 0.22 0.065 Comp. 4 1 0.14 0.1 0.040 Comp. 4 2 0.13 0.09 0.040 Comp. 4 Average 0.135 0.09 0.045 Comp. 5 1 0.15 0.11 0.040 Comp. 5 2 0.16 0.12 0.040 Comp. 5 Average 0.155 0.115 0.040

[0089] Optimal greases have as low static and dynamic coefficients of friction as possible and as small a difference between said static and dynamic values. It was unexpectedly identified that Example 1 produced better or no worse results than each of the comparatives, despite using a silicone base stock oil having a significantly greater viscosity. The differences between the static and dynamic viscosity coefficients can also be seen to be good for Example. 1.

[0090] In a further series of experiments the rubber compatibility of different rubbers with Example 1 in terms of shore hardness change and weight change by comparing a blank rubber sample to a grease treated rubber sample using the following methods.

[0091] 1. Rubber Compatibility Test—Weight Loss (DIN 53521-1987-11). [0092] Rubber tensile bars of shape “S2” were cleaned lightly with a lintless textile or tissue (if needed isopropyl alcohol was used as a cleaning fluid). The resulting cleaned test bars were then coated completely in Example. 1 grease composition. The resulting samples were then stored at 70° C. for 96 hours the un-treaded and treaded test pieces were cleaned and balanced again. The weight differences were calculated and the value reported in g and % weight difference

TABLE-US-00009 TABLE 9a Rubber compatibility test - Weight loss (DIN 53521 - 1987 - 11). Blank sample without grease treatment Weight before/ Result Materials Sample after (g) (%) Neoprene 1 1.5355 1.5323 −0.21 2 1.5074 1.5050 −0.16 3 1.3610 1.3584 −0.19 Polyurethane (PU) blend 1 1.0470 1.0411 −0.56 grade 2 1.1075 1.1010 −0.59 3 1.2109 1.2040 −0.57 Polyurethane (PU) Shore 1 1.0428 1.0383 −0.43 80 2 0.9746 0.9704 −0.43 3 0.8488 0.8458 −0.35 Styrene-butadiene rubber 1 0.9698 0.9649 −0.51 (SBR) 2 1.1055 1.1001 −0.49 3 0.9101 0.9064 −0.41 Ethylene propylene diene 1 1.0099 1.0052 −0.47 monomer (EPDM) 2 0.9365 0.9314 −0.54 3 0.9521 0.9458 −0.66 Acrylonitrile butadiene 1 1.2455 1.2405 −0.40 rubber (NBR) 2 1.1763 1.1724 −0.33 3 1.0087 1.0048 −0.39 VITON ® 1 1.2369 1.2334 −0.28 Fluoroelastomer 2 1.3416 1.3380 −0.27 3 1.2395 1.2363 −0.26

[0093] All blank samples showing after storing at 70° c. for 96 h a weight loss between 0.16 and 0.66 weight %

TABLE-US-00010 TABLE 9b Rubber compatibility test - Weight loss (DIN 53521 - 1987 - 11) after silicone grease had been applied Materials (treated with Weight before/ Result Silicone Lubricant) Sample after (g) (%) Materials Neoprene 1 1.5743 1.5554 −1.20 2 1.5794 1.5620 −1.10 3 1.6223 1.6033 −1.17 Polyurethane (PU) blend 1 1.1553 1.1452 −0.87 grade 2 1.0820 1.0727 −0.86 3 1.1973 1.1871 −0.85 Polyurethane (PU) Shore 1 0.8472 0.8405 −0.79 80 2 0.9639 0.9563 −0.79 3 0.9373 0.9303 −0.75 Styrene-butadiene rubber 1 0.7704 0.7295 −5.31 (SBR) 2 0.8559 0.8070 −5.71 3 0.8718 0.8187 −6.09 Ethylene propylene diene 1 0.9693 0.8957 −7.59 monomer (EPDM) 2 0.9566 0.8831 −7.68 3 0.9753 0.9122 −6.47 Acrylonitrile butadiene 1 1.0542 1.0305 −2.25 rubber (NBR) 2 1.0916 1.0678 −2.18 3 1.1144 1.0899 −2.20 VITON ® 1 1.3550 1.3472 −0.58 2 1.2266 1.2195 −0.58 3 1.2292 1.2219 −0.59

[0094] All rubber samples showing a very good (<5%) to acceptable (>5-<10%) weight loss after storing at 70° c. for 96 h.

[0095] 2. Rubber Compatibility Test—Shore A Hardness [0096] A Shore hardness tester (Digi test II) (durometer) was used to measure the depth of an indentation in the rubber material created by a given force on a standardized presser foot following the standard method in DIN ISO 7619-1:2012 02. Tests were made using blank Samples (i.e., not previously treated with lubricant) and after treating with lubricant. The results are depicted in Table 10 below.

TABLE-US-00011 TABLE 10 Rubber Compatibility Test - Shore A Hardness Blank Sample Sample with silicone Shore Hardness grease Shore Hardness Rubber type Difference (Δ) Difference (Δ) Neoprene 2.80 2.70 Polyurethane (PU) blend −3.10 −4.30 grade Polyurethane (PU) Shore 80 −4.10 −4.70 Styrene-butadiene rubber 2.80 6.60 (SBR) Ethylene propylene diene −1.40 5.40 monomer (EPDM) Acrylonitrile butadiene 0.90 0.60 rubber (NBR) VITON ® −1.90 −1.30

[0097] All rubber samples showing a very good (Δ<+/−5) to acceptable (Δ>+/−5-<+/−10) shore hardness change after storing at 70° c. for 96 h.