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
  • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
  • C10M105/08—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing oxygen
  • C10M105/32—Esters
  • C10M105/40—Esters containing free hydroxy or carboxyl groups
• • 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
  • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
  • C10M105/08—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing oxygen
  • C10M105/32—Esters
  • C10M105/42—Complex esters, i.e. compounds containing at least three esterified carboxyl groups and derived from the combination of at least three different types of the following five types of compound: monohydroxy compounds, polyhydroxy compounds, monocarboxylic acids, polycarboxylic acids and hydroxy carboxylic acids
• • 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
  • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated
  • C10M171/008—Lubricant compositions compatible with refrigerants
• • 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
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/28—Esters
  • C10M2207/281—Esters of (cyclo)aliphatic monocarboxylic acids
• • 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
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/28—Esters
  • C10M2207/282—Esters of (cyclo)aliphatic oolycarboxylic acids
• • 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
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/28—Esters
  • C10M2207/283—Esters of polyhydroxy compounds
• • 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
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/28—Esters
  • C10M2207/286—Esters of polymerised unsaturated acids
• • 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
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/28—Esters
  • C10M2207/287—Partial esters
  • C10M2207/289—Partial esters containing free hydroxy groups
• • 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
  • C10M2211/00—Organic non-macromolecular compounds containing halogen as ingredients in lubricant compositions
  • C10M2211/02—Organic non-macromolecular compounds containing halogen as ingredients in lubricant compositions containing carbon, hydrogen and halogen only
  • C10M2211/022—Organic non-macromolecular compounds containing halogen as ingredients in lubricant compositions containing carbon, hydrogen and halogen only aliphatic
• • 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
  • C10M2211/00—Organic non-macromolecular compounds containing halogen as ingredients in lubricant compositions
  • C10M2211/06—Perfluorinated compounds
• • 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
• • 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
  • C10N2040/30—Refrigerators lubricants or compressors lubricants
• • 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
  • C10N2040/32—Wires, ropes or cables lubricants
• • 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
  • C10N2040/34—Lubricating-sealants
• • 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
  • C10N2040/36—Release agents or mold release agents
• • 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
  • C10N2040/38—Conveyors or chain belts
• • 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
  • C10N2040/40—Generators or electric motors in oil or gas winning field
• • 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
  • C10N2040/42—Flashing oils or marking oils
• • 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
  • C10N2040/44—Super vacuum or supercritical use
• • 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
  • C10N2040/50—Medical uses

Definitions

• the invention relates to the use of citric acid esters as lubricants for refrigerant compressors which are operated with chlorine-free, partially fluorinated hydrocarbons as refrigerants.
• Refrigerant compressors are widely used to generate refrigeration in industrial, commercial and private areas. These devices work with mechanical compressors that compress the refrigerant, liquefy in the condenser by cooling with air, water or another medium and evaporate in the evaporator with the absorption of heat from the medium to be cooled.
• the main refrigerants used are ammonia for large systems and chlorofluorocarbons such as dichlorodifluoromethane, chlorotrifluoromethane for large systems, commercial refrigeration systems and for household appliances.
• Highly refined, white oil-like, generally naphthenic mineral oils are used to lubricate refrigerant compressors.
• Alkylaromatics and also poly-alpha-olefins are used as fully synthetic oils for refrigerant compressors.
• the task of the lubricating oils is to lubricate the moving compressor parts, to dissipate the heat from the hot compressor parts and to seal the compression chamber and the valves. These tasks also determine the properties that the lubricating oils must meet. They have to be able to withstand thermal loads and also remain fluid at the evaporator temperatures. In addition, it must be taken into account that the lubricating oils are discharged from the compression chamber into the refrigerant circuit and cannot be completely removed by downstream oil separators. They must therefore be miscible with the refrigerant in wide temperature and concentration ranges, so that the return of lubricating oil that has entered the refrigerant circuit is ensured in the compressor.
• Chlorofluorocarbons have been suspected for some time of damaging the ozone layer of the earth's atmosphere. Therefore, efforts are being made to limit their use to those cases in which they cannot be replaced. For the rest, one tries to replace them with substances that have the same effect but are harmless.
• chlorine-free, partially fluorinated hydrocarbons such as 1,1,1,2-tetrafluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, pentafluoroethane, 1,1,1,3, 3,3-hexafluoropropane and trifluoromethane can be used. These materials are characterized by high thermal stability and corresponding thermodynamic properties in the temperature ranges that occur during the operation of refrigerant compressors.
• polyalkylene glycols There are limits to the use of polyalkylene glycols in that they are highly hygroscopic. Drying them to a residual moisture of ⁇ 100 ppm requires a great deal of technical effort. In addition, care must be taken to ensure that moisture is not absorbed again by completely excluding the air. They can therefore only be used in hermetically sealed, small refrigeration systems, e.g. Household refrigerators. In large refrigeration systems, where maintenance work with occasional interventions in the refrigerant circuit is required, considerable moisture absorption can be expected over time. The moisture bound to the polyalkylene glycol can no longer be removed with the help of filter dryers. This leads to problems with metallic materials in the system. Furthermore, the thermal stability of the polyalkylene glycols does not meet all requirements. Above about 180 ° C, such a temperature can occur in the compressor pressure valve under extreme operating conditions, they begin to decompose.
• Ester oils are better than polyalkylene glycols for the lubrication of refrigerant compressors in which chlorine-free, Partially fluorinated hydrocarbons are used as refrigerants (EP 445 611 A1).
• the term ester oils is understood to mean esters of di- or polycarboxylic acids with monohydric alcohols or esters of monocarboxylic acids with dihydric or polyhydric alcohols.
• malonic acid, succinic acid, adipic acid, sebacic acid, pelargonic acid, 1,12-dodecanedioic acid and, as the only compound which contains more than two carboxyl groups, butane tetracarboxylic acid are mentioned as examples.
• ester oils have proven themselves in many cases as lubricants for refrigerant compressors, there is still a need for further lubricants that can be used even more universally than the known or that solve individual lubrication problems.
• the object was therefore to provide further lubricants for refrigerant compressors which meet the requirements described and can always be used when chlorine-free, partially fluorinated hydrocarbons are used as refrigerants.
• the invention consists in the use of esters of citric acid with monohydric alcohols as lubricants for refrigerant compressors which are operated with chlorine-free, partially fluorinated hydrocarbons as refrigerants.
• Citric acid esters are already being used commercially in various areas of technology. They are used as plasticizers as well as for the production of protective layers and adhesion promoters. Because of their physiological tolerance, they have also found their way into food technology and cosmetics. However, their use as a lubricant, in particular as a lubricant for refrigerant compressors, has not yet been described.
• citric acid is esterified with straight-chain or branched, primary monohydric alcohols, among which those with 2 to 20 carbon atoms are preferred. Branched-chain, but also straight-chain, primary alcohols with at least 4 carbon atoms have proven to be particularly suitable.
• alcohols examples include n-butanol, 2-ethylbutanol, 2-methylpentanol, n-hexanol, heptanol (in the form of the isomer mixture), n-octanol, octanol (in the form of the isomer mixture), 2-ethylhexanol, i-nonanol, i -Decanol, i-tridecanol, i-hexadecanol and i-octadecanol.
• the alcohols mentioned are obtained predominantly from olefins by oxosynthesis and subsequent hydrogenation of the aldehydes formed. All technically significant olefins are accessible to oxosynthesis in its various variants. It usually leads to a mixture of isomeric alcohols. It is not necessary to separate these mixtures to prepare the esters.
• Another way of obtaining alcohols which are suitable for the production of citric acid esters is the aldol condensation of low molecular weight aldehydes, followed by the hydrogenation of the unsaturated, higher molecular weight aldehydes which have formed. In this case, too, the mixture of isomeric alcohols obtained need not be separated.
• the property profile of the citric acid esters used as lubricants can be further influenced by acylation of the hydroxyl group present in the citric acid molecule. It opens up an additional possibility of specifically solving lubrication problems that arise by using citric acid esters.
• Suitable as Acylating agents are aliphatic monocarboxylic acids with up to 13 carbon atoms, preferably 1 to 10 and in particular 2 to 4 carbon atoms.
• Citric acid esters are prepared in a known manner from commercially available citric acid and alcohols in the presence of acidic catalysts. Mineral acids such as sulfuric acid, phosphoric acid and their acid salts, furthermore trialkyl or triaryl phosphates and p-toluenesulfonic acid are suitable as catalysts. In order to achieve the most complete possible reaction, it is advisable to use one of the reactants in excess and / or to separate the water of reaction continuously by distillation, optionally with the addition of an azeotrope such as cyclohexane or toluene.
• an azeotrope such as cyclohexane or toluene.
• esters are used and reacted with the acid or, more appropriately, with the acid anhydride, preferably in excess, in the presence of an acid catalyst.
• the acyl halides in particular the acyl chlorides, are also used successfully as the acylating reagent.
• the lubricants used according to the invention have good miscibility with the chlorine-free, partially fluorinated hydrocarbons used as refrigerants, even at -40 ° C., that is to say in the temperature ranges which can occur in compression refrigeration systems.
• Their viscosity at 40 ° C is between about 10 and 100 mm2 / s and thus corresponds to the requirements placed on the lubricant for the above-described area of application.
• the esters are not hygroscopic. They can therefore be dried without much effort. Residual moisture, which may not exceed 35 ppm according to the German standard DIN 51 503, can be easily achieved.
• esters used as lubricants can be used in pure form, as a mixture of isomeric compounds and as a mixture of two or more esters of different chemical compositions.
• esters are prepared in the following examples and their properties are listed insofar as they are important for the use of the esters as lubricants.
• the scope of the invention is not limited to the described embodiments.
• the catalyst contained in the crude ester is neutralized with 5% by weight NaHCO3 solution (pH 9-9.5) and the organic phase is washed several times with water after phase separation.
• the ester is then in a nitrogen stream at a pressure of 20 - 30 hPa and a temperature of 130 ° C 5 Hours dried. After filtration, 572.0 g of tri-i-nonyl citrate are obtained, which corresponds to a yield of 97%.
• VZ (mg KOH / g) measured: 283 calculated: 295 Density (40 ° C) (g / cm3) 0.9413 V40 (mm2 / s) 64.3
• the water of reaction obtained is removed from the reaction mixture as an azeotrope with the aid of cyclohexane.
• the organic phase After adding 10% by weight sodium hydroxide solution, the organic phase is adjusted to a pH of 9 and washed neutral with water several times at about 60.degree.
• ester is then dried in a stream of nitrogen at a pressure of 20-30 hPa and a temperature of 120 ° C. for 6 hours. After filtration, 520.4 g of ester are obtained, which corresponds to a yield of 95%.
• VZ (mg KOH / g) measured: 314 calculated: 318 Density (40 ° C) (g / cm3) 0.9556 V40 (mm2 / s) 33.1
• the sulfuric acid contained in the crude product is neutralized by adding 5% strength by weight sodium hydroxide solution and, after phase separation, the organic phase is washed neutral with water.
• the crude ester is then dried in a stream of nitrogen at a pressure of 15-20 hPa and a temperature of 110 ° C. for 5 hours. After filtration, 450.6 g of 2-acetyl-tri (i-nonyl) citrate are obtained, which corresponds to a yield of 92%.
• the organic phase is adjusted to a pH of 7.02 by adding 1342 g of 20% strength by weight NaOH.
• the phases are separated and the organic phase is washed neutral with water.
• the crude ester is then dried in a nitrogen stream at a pressure of 10-20 hPa and a temperature of 100 ° C. for 5 hours. After filtration, 523.1 g of product are obtained, which corresponds to a yield of 91.4%.
• VZ (mg KOH / g) measured: 413 calculated: 393 Density (20 ° C) (g / cm3) 0.9820 V40 (mm2 / s) 40.1
• esters described above as lubricants are their viscosity and their miscibility with 1,1,1,2-tetrafluoroethane as refrigerant.
• the viscosity of the esters is measured in an Ubbelohde viscometer at 40 ° C.
• esters Viscosity (mm2 / s at 40 ° C) Miscibility in the range from -40 to + 80 ° C 1.
• Tri-i-nonyl citrate 64.9 Mixing gap, but miscible in the work area 2.
• Tri- (2-ethylhexyl) citrate 33.1 Mixing gap, but miscible in the work area 3.
• esters described in the table are thermally stable. No decomposition was found up to 200 ° C, i.e. They can be used without restriction under normal working conditions, in which temperatures of 175 ° C are not exceeded.

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Citations (5)

• 1992
  • 1992-03-24 DE DE4209502A patent/DE4209502A1/de not_active Ceased
• 1993
  • 1993-03-15 EP EP93104174A patent/EP0562405A1/fr not_active Withdrawn

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