Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
  • C10M169/02—Mixtures of base-materials and thickeners
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
  • C10M2213/02—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions obtained from monomers containing carbon, hydrogen and halogen only
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
  • C10M2213/04—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions obtained from monomers containing carbon, hydrogen, halogen and oxygen
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
  • C10M2213/06—Perfluoro polymers
  • C10M2213/0606—Perfluoro polymers used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
  • C10M2213/06—Perfluoro polymers
  • C10M2213/062—Polytetrafluoroethylene [PTFE]
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/01—Physico-chemical properties
  • C10N2020/055—Particles related characteristics
  • C10N2020/06—Particles of special shape or size
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/06—Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/40—Low content or no content compositions
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/02—Bearings
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2050/00—Form in which the lubricant is applied to the material being lubricated
  • C10N2050/10—Semi-solids; greasy

Definitions

• the present invention relates to lubricating grease compositions based on (per)fluoropolyethers, having low friction coefficients and reduced wears, particularly suitable to be used for example in bearings working at high speed in a wide range of temperatures.
• Greases obtained by said (per)fluoropolyethers by the addition of thickeners are also known, among which the most commonly used is polytetrafluoroethylene (PTFE) in powder.
• PTFE polytetrafluoroethylene
• EP 856,570 antiseizing pastes prepared by addition to a perfluoropolyether oil having a viscosity between 20 and 2,000 cSt at 20° C. of a PTFE in powder having molecular weight between 100,000 and 700,000 and particle size from 2 to 7 micron, the PTFE being obtained by irradiation with gamma rays or with electron beam of PTFE powder and subsequent milling.
• An object of the present invention are (per)fluoropolyether lubricating greases comoprising:
• the surfactant content of 20 ppm represents the sensitivity limit of the analytical determination as described in the characterization of the Examples.
• the drying to obtain component B) is carried out at a temperture in the range 105° C.-190° C., preferably 110-140° C.
• Generally powder particle aggregates are obtained having an average size between 10 and 30 micron.
• the perfluoropolyether oils of component A) are selected from the following classes: E—O—(CF(CF 3 )CF 2 O) m′ (CFXO) n′ —E′ (1)
• the preferred perfluoropolyether oils are those of the classes (1), (4), (5) or their mixtures and are available on the market with the trademark FOMBLIN® marketed by Solvay Solexis.
• Component B) is selected between the TFE homopolymer (PTFE) and the TFE copolymers with 0.01-1% by weight of a comonomer having an ethylene type unsaturation.
• those olefinic, acrylic and styrene can be mentioned as, for example, ethylene, propylene, methylmethacrilate, (metha)acrylic acid, butylacrylate, hydroxyethylhexylacrylate, styrene, C 3 -C 8 pefluoroolefins, as hexafluoropropene (H—FP);
• C 2 -C 8 fluoroolefins containin hydrogen, as vinyl fluoride (VF), vinylidene fluoride (VDF), trifluoroethylene, hexafluoroisobutene, CH 2 ⁇ CH—R f perfluoroalkylethylene, wherein R f is a C 1 -C 6 perfluoroalkyl;
• the preferred comonomers are perfluoropropyl-vinylether (PVE) and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole (TTD).
• aqueous latex of polytetrafluoroethylene or of the tetrafluoroethylene copolymer with another monomer having an ethylene type unsaturation, used to prepare component B), is known and is prepared according to what described in U.S. Pat. No. 6,297,334 herein incorporated by reference.
• the preparation of the TFE polymer latex comprises the following steps:
• microemulsion used in the latex preparation is described in U.S. Pat. No. 4,864,006 and U.S. Pat. No. 4,990,283.
• the latex is coagulated and the obtained polymer particles are dried.
• the coagulation is carried out by addition of an electrolyte.
• the electrolyte can be an inorganic acid or an inorganic salt.
• the acids it can be mentioned nitric acid, hydrochloric acid, sulphuric acid; among the salts, it can be mentioned potassium nitrate, ammonium carbonate, magnesium sulphate, aluminum sulphate, potassium carbonate, calcium nitrate, sodium chloride.
• nitric acid or ammonium carbonate are used.
• the drying of the coagulated latex is carried out at a temperature in the range 105° C.-190° C., preferably 110°-140° C., for a time between 20 and 60 hours.
• a further object of the present invention is a process for the preparation of the invention (per)fluoropolyether greases comprising the following steps:
• step a) after the (per)fluoropolyether oil A) introduction in the mixer, generally a degassing under vacuum at 60° C. for 2 hours at 0.1 mbar is carried out.
• step b) the addition of the powder of component B) to the oil is generally carried out in at least 3 hours until reaching the desired composition.
• step c) the stirring is carried out in a constant way, for about 8 hours, under vacuum.
• step d) The refining of step d) is generally carried out in a three-cylindrical refiner.
• the grease obtainable with this process has, as said, an amount of water lower than 100 ppm, preferably lower than 60 ppm and a surfactant amount lower than 20 ppm.
• the greases of the present invention can be used as such or can be additioned with the known additives of the prior art, as, for example, antirust, antiwear, antioxidants, stabilizers.
• the invention greases can be formulated depending on the amounts of A) and B) so to have different penetration degrees.
• the penetration is determined according to the ASTM D-217 method and the greases are classified according to the NLGI scale from 000 degree, corresponding to a penetration value of 475 mm/10′, to 6 degree, corresponding to 85 mm/10′.
• the greases of the present invention result more stable, in applications requiring high temperatures, since the thickener is directly formulated with (per)fluoropolyether oil without using surfactants.
• the greases of the present invention contain, the penetration being equal, compared with the known (per)fluorinated greases, a much lower amount of thickening agent (PTFE).
• PTFE thickening agent
• the invention greases are used in the lubrication of mechanical parts and their combination of very good properties makes them particularly suitable in the lubrication of bearings working at high speed and in a wide range of temperatures.
• the greases of the present invention are applicable with significant advantages in the lubrication of microbearings, microgears, preferably in plastic, for example mechanical actuators, extending their life and significantly reducing the running noise.
• the invention greases show furthermore a very low toxicity since they are formed of substantially stable and inert (per)fluoropolyether oils and PTFE.
• the number average molecular weight of PTFE is calculated from the first melting temperature, if lower than 327° C., as described in EP 481,509, or by the absolute specific weight datum according to what described by Doban R. C., Knight A. C., Peterson J. H, Sperati C. A. in “Meeting of the American Chemical Society” Atlantic City, September 1956.
• the average particle diameter is measured by Laser Light Scattering based on the laser light diffusion (Photon Correlation Spectroscopy).
• the used instrument consists of an Argon laser light source having a wave length of 514.5 nm by Spectra-Physics and in a photocorrelator by Brookhaven 2030 AT model.
• the scattering measurement is carried out at 25° C. on latex samples diluted with filtered water and at an angle of 90°.
• the particle diameter in the latex is calculated by applying the cumulant method.
• g PTFE/l water ( Wess ⁇ Wtara )/( Winiz ⁇ Wess )*1000
• 0.5 g of powder are wet with ethanol and brought to basic pH with a NH 4 OH solution.
• the powder is dried under nitrogen flow, to the dried powder 2 ml of acidified methanol with some drops of concentrated H 2 SO 4 are added, the whole is brought into a hermetically sealed test tube heated at 70° C. for 70 hours to carry out the surfactant esterification.
• To the obtained mixture 5 ml of Delifrene A 113 and 4 ml of water are then added. It is let stand. Two phases are separated, a ⁇ litre of the lower fluorinated phase containing the surfactant ester is taken.
• the fluorinated phase is gaschromatographically analyzed by injecting it in a 3 m long glass column, with a diameter of 3 mm, filled with a stationary phase constituted by Carbovax 20M absorbed at 25% by weight on Chromosorb W 80-100 mesh.
• the method sensitivity limit is 20 ppm.
• the test is carried out according to the ASTM D 217 method.
• a ball bearing (SKF 6303 model), cleaned with n-hexane and dried, is filled at 30% by weight, with respect to the grease weight required for the total filling, with the grease to be tested and the suitable screens are inserted to avoid the material coming out.
• the so assembled bearing is mounted on a shaft, connected to an engine, equipped with suitable housing couple and tightened.
• the cup wherein the bearing is placed is equipped with a loading cell which allows to measure the bearing stress during the running.
• On the outer race of the bearing a thermocouple is positioned detecting the temperature evolution during the test.
• the test is carried out by making the bearing to start at 5,000 rpm and maintaining such speed for 2 hours.
• the test result is given by the initial take-off value in mN•m, stress after steady conditions of 2 hours in mN•m, oscillation of the steady condition value and maximum temperature reached at the end of the test.
• test conditions are the following: a speed gradient is set from 0 to 16,000 rpm with step of 2000 rpm, each lasting 1 hour.
• the test duration is of total 8 hours and the stress value after 1 hour at 16,000 rpm and the maximum temperature reached are evaluated.
• a perfectly clear microemulsion is obtained in the temperature range from 2° C. to 46° C.
• the reactor is maintained under mechanical stirring. 1,200 g of 2,2,4-trifluoro-5-trifluoro-methoxy-1,3-dioxole (TTD) and 100 mmHg of ethane are fed into the reactor.
• TTD 2,2,4-trifluoro-5-trifluoro-methoxy-1,3-dioxole
• ethane 100 mmHg
• the reactor is pressurized at 20 bar with C 2 F 4 and heated to 90° C. At this point 700 cc of a solution of ammonium persulphate (initiator) equal to 14 g are fed into the reactor.
• TFE tetrafluoroethylene
• the so obtained latex has a concentration of 440 g/l and an average particle diameter of 50 nm.
• the latex is diluted until bringing the polymer concentration to 7% by weight and 20 litres of said latex are introduced at a temperature of 24° C. in a 50 litre reactor.
• the latex is additioned under stirring with an aqueous solution of (NH 4 ) 2 CO 3 at 15% so to bring the pH to 8.
• the wet powder is then subjected to two washings with 20 litres of water at the temperature of 24° C., under stirring for 5 minutes.
• the wet powder is then discharged and dried in a static oven at 120° C. for 48 hours.
• the analyzed grease shows a water content of about 50 ppm.
• Example 1B is repeated but by introducing 900 g of the oil described in the Example 1B and 600 g of a commercial PTFE Algoflon® L203 having a number average molecular weight of 500,000, obtained from a latex having a particle diameter of 200-300 nm, by successive steps of about 100 g at a time.
• Example 1B is repeated but by using 1,200 g of oil (Fomblin® Z15), having the following structure: CF 3 —[(O—CF 2 CF 2 ) n —(O—CF 2 ) m ]—O—CF 3 with n/m ⁇ 1 and kinematic viscosity at 40° C. of 92 cSt, and 300 g of PTFE of the Example 1A.
• oil Fomblin® Z15
• the analyzed grease shows a water content of about 50 ppm.
• Example 3 is repeated by introducing 900 g of the oil described in the Example 3 and 600 g of a commercial PTFE Algoflon® L203 described in the Example 2.
• the Example 1B has been repeated but by using as PTFE the commercial PTFE of the Example 2 (comparative).
• the obtained grease has shown a penetration degree higher than 400.

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• 2003
  • 2003-10-03 IT IT001913A patent/ITMI20031913A1/it unknown
• 2004
  • 2004-09-24 EP EP04022779A patent/EP1520906A1/de not_active Withdrawn
  • 2004-09-28 US US10/950,557 patent/US20050075250A1/en not_active Abandoned
  • 2004-10-01 JP JP2004290639A patent/JP2005113143A/ja not_active Withdrawn

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