PFPE Lubricating GreaseDr. Martin Schweigkofler, Dr. Stefan Grundei, Dr. Wallace Zhang, Jocelyn ZhaoDr. Thomas Kilthau, Dr. Martin Schmidt-Amelunxen, Dr. Stefan Seemeyer,Klüber Lubrication München SE & Co. KGKlüber Lubrication Industries (Shanghai) Co.,Ltd.AbstractThe paper discloses lubricating greases which contain perfluoropolyether. Composition1.PFPE oilLubrication greases use base oils like mineral oils, native oils, and synthetic hydrocarbon oils, such as PAO, alkylated naphthalines, alkylated phenylethers, silicone oils, ester oils, polyglycols and so on. All these base oils contain hydrogen bonded to Carbon, i.e. CH, CH2 and CH3 groups. These base oils cannot be used at very high temperatures and can react with different chemicals like oxidizing materials. Some of them are not sufficiently stable against hydrolysis or nucleophilic substances, e.g. amines. These hydrocarbon oils can also have a strong undesired impact on seal materials or components made out of plastics such as POM, Polyamides and PEEK.These weakness can be minimized or avoided by using Perfluoropolyether (PFPE) of the general formulaX´O(CF2O)m(CF2CF2O)n[CF2CF(CF3)O]s [CF(CF3)O]u(CF2CF2CF2O)v X (I)As base oil or part of the base oil.In drawing (I) the perfluoroalkyloxy units can be distributed randomly throughout the chain. The subscripts m, n, s, u, and v can independently be 0 to maximal 200. The molecular weight of the material for example determined by the ratio of the terminal groups compared to the internal groups via NMR analysis can be up to 20000 u.The kinematic viscosity of the perfluoropolyether can be between 5 and 2000 mm²/sec at 40°C, more preferable between 15 and 1300 mm²/sec.The pour point of the perfluoropolyether can be as low as – 80°C.The end groups X and X´ can be can be short chain perfluoroalkyl groups like CF3, C2F5, C3F7,fluorine groups is substituted by a hydrocarbon group, hydrogen, hydroxyl groups, amine groups, amid groups, carbonyl groups, or other functional groups.2.PFPE based greaseTypical PFPE lubricating grease is composed by base oil and thickener. In some PFPE grease, one or more additives are added as well.The NLGI class of the greases can be between 000 and 5, preferred between 0 and 3, even more preferred between 1 and 3.a)Base oili.Pure PFPE base oilThe perfluoropolyether can be used alone or in mixtures of two or more of the possibletypes as indicated by formula I.ii.Hybrid base oilThe base oil can be also composed by one or more type perfluoropolyether, mixed with one or more from the following type oil: mineral oils, synthetic oils or native oils. Typical ratio of PFPE to the other oils is in the range of 1:10 to 10:1.The synthetic oils are selected from an ester of an aliphatic or aromatic di-, tri- ortetracarboxylic acid with one or a mixture of C7 to C22 alcohols, a polyphenyl ether oralkylated diphenyl ether, an ester of trimethylolpropane, pentaerythritol or dipentaerythritol with aliphatic C7 to C22 carboxylic acids, C18 dimer acid esters with C7 to C22 alcohols, complex esters, individual components or in any mixtures. In addition, the synthetic oil may beselected from poly-α-olefins, metallocene catalyzed PAO, alkylated naphthalenes, alkylated benzenes, polyglycols, silicone oils, or alkylated diphenylether.The mineral oils may be selected from paraffin-basic, naphthene-basic, aromatichydrocracking oils; gas to liquid (GTL) liquids, GTL refers to a gas to liquid method anddescribes a method for production of fuel from natural gas. Natural gas is converted bysteam reforming to synthesis gas, which is then converted by Fischer-Tropsch synthesis to fuels by using catalysts. The catalysts and the process conditions control the type of fuel, i.e., whether gasoline, kerosene, diesel or oils are produced. Coal may also be used as a rawmaterial in the same way by the coal to liquid method (CTL) and biomass may be used as a raw material in the biomass to liquid (BTL) method.Triglycerides from animal/vegetable sources that have been upgraded by known methods such as hydrogenation may be used as native oils. The especially preferred triglyceride oils are genetically modified triglyceride oils with high oleic acid content. Typical vegetable oils used therein and genetically modified or cultured having a high oil content include safflower oil, corn oil, canola oil, sunflower oil, soybean oil, linseed oil, peanut oil, lesquerella oil,meadowfoam oil and palm oil. The native oils might further be processed e.g. polymerization processes.b)thickenerThe thickener material used can be fluorinated polymers like polytetrafluoroethylene (PTFE), oxides like silica, organic carbonic acid salts, boron nitride, carbides like silicon carbide, poly- or diurea compounds, polyimides or polyamidimides, melamine cyanurates, graphite, carbon black, carbon nanotubes, molybdates, phosphates.The PTFE used can be produced by polymerization of tetrafluorethylene in suspension or dispersion. To adjust the particle size and the polymer chain length processes like grinding, thermal treatment or irradiation processes can be used. PTFE powders treated as indicated above are e.g. known as micronized PTFE, but also dispersion processes leading to lowmolecular weight PTFE are known. These PTFE products can be used without the processes indicated above.Typical molecular weights are between 10000 g/mol and 10exp8 g/mol, preferred between 100000 g/mol and 10exp7 g/mol.Also recycling of PTFE by processes as indicated above can produce PTFE powders that can be used for thickeners of lubricants.The organic acids can be saturated or unsaturated, branched or unbranched, mono or di or tri or polyacids containing 6 to 25 carbon acids and their mixtures like stearic acid,hydroxystearic acid, benzoic acid, oleic acid, acelaic acid, sebacic acids, behenic acid, amid groups containing acids. Amid group containing acids can for example be prepared byreacting primary or secondary aliphatic amines with di-acids or di-esters of aliphatic oraromatic carbonic acids.The cations of the organic acid salts can be lithium, sodium, potassium, magnesium, calcium, aluminum, barium or zinc.The urea compounds are reaction products of aliphatic or aromatic mono or diisocyanatemixtures. Examples for suitable urea compounds are reaction products of diisocyanates, preferably 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene,4,4′-diisocyanatodiphenylmethane, 2,4′-diisocyanatodiphenylmethane,4,4′-diisocyanatodiphenyl, 4,4′-diisocyanato-3,3′-dimethyldiphenyl,4,4′-diisocyanato-3,3′-dimethylphenylmethane which may be used individually or incombination, with an amine of the general formula R′2N—R or a diamine of the generalformula R′2N—R—N—R′2 where R is an aryl, alkyl or alkylene radical with 2 to 22 carbon atoms and R′ is identical to or different from a hydrogen, an alkyl, alkylene or aryl radical, or with mixtures of amines and diamines.These thickener materials can be used alone or in combination.The particle size of the thickener is usually below 100µ, preferred below 20 µm.The amount of thickener material is below 50 %, preferred below 40 %c)AdditivesAdditionally additives can be used to improve the EP, anti-corrosion properties, frictionproperties, wear properties, oxidation resistance properties. The additives can be materials soluble in PFPE oils or insoluble materials.PFPE soluble materials comprise one or more functional groups based on phosphates,phosphazenes, triazines, aromatic nitro compounds, acid amides, carbonic acid derivatives, ammonium salts and linking groups or end groups consisting of PFPE moieties like groups (II) and (III),CbF(2b+1)O(CF2O)m(CF2CF2O)n[CF2CF(CF3)O]s [CF(CF3)O]u(CF2CF2CF2O)v- (II)-O(CF2O)m(CF2CF2O)n[CF2CF(CF3)O]s [CF(CF3)O]u(CF2CF2CF2O)v- (III).PFPE insoluble additives can be metal molybdates, metal phosphates, salt of organic acids, nitrite salts, metal sulfides like molybdenum disulfide or zinc sulfide, oxides like silicates, hexagonal boron nitride, metal oxides or hydroxides or hydrogen carbonates and theirmixtures.The cations in the mentioned oxides, hydroxides, hydrogen carbonates and carbonates can be derived from alkaline or earth alkaline metals like sodium, lithium, magnesium, potassium, calcium.Further additives which are not soluble in PFPE can be arylamine derivatives, phenolderivatives, metal salts of organic carbonic or sulfonic acids or phosphoric acids ofThe additives can for example be chosen from the group comprising butyl hydroxy toluene, dialkyl diphenylamines, styrolized diphenylamines, alkylated phenyl-alpha-naphthylamines, polymeric trimethyl dihydroquinoline, sulfurized fatty acid esters, diphenyl cresyl phosphate, amine-neutralized phosphates, alkylated and non-alkylated triaryl phosphates, alkylated and non-alkylated triaryl thiophosphates, zinc-dialkyl dithiophosphates, carbamates, thiocarbamates, zinc-dithiocarbamates, dimercaptothiadiazole, succinic acid semi-ester, calcium sulfonates, benzotriazole derivatives, K-pentaborates, Na-thiosulfates, andNa-pyrophosphates.The amount of additives in the grease can be up to 15 % by weight, more preferable less than 10 % by weight.ApplicationThe lubricant formulations can be used in technical components like bearings, gears, chains, screws, valves, spindles, actuators, armatures, electrical contacts, ropes, combustion and electrical motors, seals, pneumatic or hydraulic devices, compressors, brakes.Bearing industry, automotive industry, automotive supplier industry, foil producing industry, wood panel industry, food processing industry, cement industry, mining industry, marine industry, convey or …..Typical formulation:Sample I1.PFPE 83% (kin.vis. @ 40°C 100 mm2/s)2.PTFE 17% D50 < 20 µmSample II1.PFPE80% (kin.vis. @ 40°C 100 mm2/s)2.PTFE 20% D50 < 20 µmSample III1.PFPE 75% (kin.vis. @ 40°C 200 mm2/s)2.PTFE 20% D50 < 20 µm3.BN 5%Sample IV1.PFPE 73% (kin.vis. @ 40°C 400 mm2/s)2.PTFE 25% D50 < 20 µm3.ZnS 2%Sample V1.PFPE 76% (kin.vis. @ 40°C 1000 mm2/s)2.PTFE 22% D50 < 20 µm3.ZnS 2%Sample VI1.PFPE 42% (kin.vis. @ 40°C 400 mm2/s)2.Trimellitate ester, 45% (kin.vis. @ 40°C 70 mm2/s)3.Urea thickener, 8%4.Alkyl phenyl amine, 2%5.Alkyl phenol, 2%6.ZnDDP, 1%Sample VII1.PFPE 37% (kin.vis. @ 40°C 400 mm2/s)2.PAO, 45% (kin.vis. @ 40°C 400 mm2/s)3.Lithium 12OH-stearate, 8%4.Lithium sebacate, 2%5.Alkyl phenyl amine, 2%6.Alkyl phenol, 2%8.Calcium sulphonate 2%Reference1.PAO, 75% (kin.vis. @ 40°C 400 mm2/s)2.Urea thickener, 8%3.Alkyl phenyl amine, 2%4.Alkyl phenol, 2%5.ZnDDP, 1%6.Calcium sulphonate 2%Table 1. Test result of PFPE greasePage | 8全氟聚醚润滑脂Dr. Martin Schweigkofler, Dr. Stefan Grundei, Dr. Wallace Zhang, Jocelyn ZhaoDr. Thomas Kilthau, Dr. Martin Schmidt-Amelunxen, Dr. Stefan Seemeyer,Klüber Lubrication München SE & Co. KG克鲁勃润滑产品（上海）有限公司摘要本文章公开了含有全氟聚醚的润滑脂。