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
  • C10M145/00—Lubricating compositions characterised by the additive being a macromolecular compound containing oxygen
  • C10M145/18—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • 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
  • C10M145/00—Lubricating compositions characterised by the additive being a macromolecular compound containing oxygen
  • C10M145/02—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C10M145/10—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a carboxyl radical, e.g. acrylate
  • C10M145/12—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a carboxyl radical, e.g. acrylate monocarboxylic
  • C10M145/14—Acrylate; Methacrylate
• • 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
  • C10M101/00—Lubricating compositions characterised by the base-material being a mineral or fatty oil
  • C10M101/04—Fatty oil fractions
• • 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
  • C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
  • C10M2209/02—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C10M2209/08—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a carboxyl radical, e.g. acrylate type
  • C10M2209/084—Acrylate; Methacrylate

Definitions

• the invention relates to a shear-stable viscosity improver for lubricating oils, especially for mineral oils of paraffinic type.
• compositions based on this improver as well as at lubricating oils comprising an effective proportion of the said improver, optionally introduced by means of the said compositions.
• Viscosity improvers are usually macromolecular compounds.
• the objective of the invention is, above all, to provide a new viscosity improver for lubricating oils, which, besides the characteristics which are conventionally sought after, namely improving the viscosity index of the said oils, exhibits a markedly improved shear strength when compared with improvers that are already known.
• Procedure CEC-L-37-T-85 is a test procedure promulgated by the Coordinating European Council (CEC) for the Development of Performance Tests for Lubricants and Engine Fuels. This procedure is used to determine shear stability of polymer-containing oils employing the FZG (Forschungsstelle f ⁇ r Zahnraderund Getriebebau) apparatus. Specifically, the purpose of the test is to determine the permanent viscosity loss of polymer- containing oils when a sample is mechanically stressed under the test conditions described.
• CEC Coordinating European Council
• the FZG gear test rig consists of drive and test gearing connected by two shafts. One shaft has a positive clutch for the application of the load.
• the test gear case contains a system for heating the test oil and a water-cooled coil to assist in cooling the test oil.
• a temperature sensor controls the heating system according to the preset temperature.
• the test rig is powered by a two speed electric motor at speeds of approximately 1500/3000 rpm.
• test lubricant is subjected to the FZG test for 7.5 minutes each at load stages 1-4 followed by
• VKA Viscosity shear stability of polymer-containing transmission lubricants. This procedure provides a means for testing lubricating oils in a taper roller bearing to determine lubricant shear stability as characterized by a reduction in the kinematic viscosity of the lubricant. It allows conclusions to be drawn on the permanent viscosity loss to be expected under operating conditions, for example, in gear boxes, and which is caused by mechanical stress.
• V* is the kinematic viscosity of the oil before shear in mm 2 /sec at 100°C
• V f is the kinematic viscosity of the oil after shear in mm 2 /sec at 100°C
• a lubricant is tested in a taper roller bearing fitted into a Four Ball EP Test Machine.
• the taper roller bearing runs submerged in 40 ml of lubricant at a constant speed and load with a test oil temperature of 60 °C during a defined number of motor revolutions (respectively during a defined running period).
• the kinematic viscosity of the test oil at 100°C is measured (in accordance with DIN 51562 or equivalent) before and after the test.
• test conditions are given in the table below:
• Test duration A 348000 revolutions (approx. 4 hours)
• Test duration B 696000 revolutions (approx. 8 hours)
• N.B. The basis for determining test duration or the number of revolutions of the motor was a theoretical speed for asynchronous motors of
• test durations are to be corrected accordingly.
• Each test duration is conducted employing a fresh lubricant sample of known kinematic viscosity. After each test duration the kinematic viscosity at 100° C is determined for the sample and the relative viscosity change Rv is determined.
• FZG machine or "FZG” test induces at the end of twenty hours about the same irreversible drop in viscosity as the "VKA” test at the end of four hours; in both cases the viscosity changes from an initial value V* at a given temperature T to a final viscosity V f at the same temperature T; the stability to shear is then characterized by the relative drop in viscosity which is given by the formula shown below:
• the objective of the invention is to provide a viscosity improver of the kind in question, which is not only capable of imparting a VIE of at least 155 to a lubricating oil exhibiting, before incorporation of the said improver, a viscosity at 100° C of 4.8 to 5.5 mm 2 /s and a VIE of 85 to 100, but which, in addition, exhibits a shear strength such that the relative drop in viscosity after four hours in the "VKA” test or after twenty hours in the "FZG” test is lower than 13 %, preferably lower than 12 % and, still more preferably, lower than 11 % .
• VIE is used to denote "Viscosity Index Extended", which is a quantity defined by ASTM standard D-2270 entitled Standard Practice for Calculating Viscosity Index from Kinematic Viscosity at 40 °C and 100°C, and which is represented by an arbitrary number employed to characterize the variation in the kinematic viscosity of a petroleum product with temperature.
• Additives of the kind in question which are already known which consist of copolymers of esters of methacrylic acid with to C lg alkanols, exhibit a shear strength which, in the above conditions of the "VKA” and “FZG” tests, is reflected in a relative drop in viscosity of the order of 20%.
• the viscosity improver in accordance with the invention is characterized in that it is capable of imparting a VIE of at least 155 to a lubricating oil exhibiting, before incorporation of the said improver, a viscosity at 100°C of 4.8 to 5.5 mm 2 /s and a VIE of 85 to 100, in that it has a shear strength such that the relative drop in viscosity after four hours in the "VKA” test or after twenty hours in the "FZG” test is lower than 13 %, preferably lower than 12 % and, still more preferably, lower than 11 %, and in that it consists either of a homo- or a copolymer essentially obtained by polymerization from at least one of the monomers of the group consisting of the esters of methacrylic acid with a long alkanol, more particularly C ⁇ 0 to C 18 and preferably C ⁇ to C 15 , the number-average molecular mass of this copolymer being from 7000 to 15,000
• the abovementioned viscosity improver consists of a copolymer essentially obtained by copolymerization from 65 to 55 parts by weight of at least one of the monomers of the group consisting of the esters of methacrylic acid with a C n to C 15 long alkanol and from 35 to 45 parts by weight of at least one of the monomers of the group consisting of the esters of methacrylic acid with a to C 4 short alkanol, the critical value of the number-average molecular mass of this copolymer being from 27,000 to 32,000 g/mol.
• copolymers constituting the viscosity improvers in accordance with the invention can be employed as they are, the quantity of copolymers used corresponding to a proportion of 2 to 40 %, preferably of 3 to 30 %, and, still more preferably, from 4 to 25 % by weight of the mass of lubricating oil to be treated.
• compositions comprising the copolymers of this invention with a normally liquid organic diluent, preferably mineral oil, forming the reaction medium within which the copolymerization is performed.
• a normally liquid organic diluent preferably mineral oil
• the mineral oil may be the same as the lubricating oil which is to be treated.
• the composition in accordance with the invention normally comprises from about 30 to about 90%, preferably from about 40 to about 80% by weight of at least one copolymer in accordance with the invention, the remainder to 100% consisting essentially of a normally liquid organic diluent, preferably mineral oil.
• the oils to be treated with the copolymers of this invention are oils of lubricating viscosity, including natural or synthetic lubricating oils and mixtures thereof.
• Natural oils include animal oils, vegetable oils, mineral oils, solvent or acid treated mineral oils, and oils derived from coal or shale.
• Synthetic lubricating oils include hydrocarbon oils, halo-substituted hydrocarbon oils, alkylene oxide polymers, esters of carboxylic acids and polyols, esters of poly carboxylic acids and alcohols, esters of phosphorus- containing acids, polymeric tetrahydrofurans, silicone-based oils and mixtures thereof.
• oils of lubricating viscosity are described in U.S. Patent No. 4,326,972 and European Patent Publication 107,282, both herein incorporated by reference for their disclosures relating to lubricating oils.
• a basic, brief description of lubricant base oils appears in an article by D.V. Brock, "Lubricant Base Oils", Lubrication Engineering, volume 43, pages 184-185, March, 1987. This article is herein incorporated by reference for its disclosures relating to lubricating oils.
• a description of oils of lubricating viscosity occurs in U.S. Patent No. 4,582,618 (Davis) (column 2, line 37 through column 3, line 63, inclusive), herein incorporated by reference for its disclosure to oils of lubricating viscosity.
• the lubricating oil composition in accordance with the invention is characterized in that it comprises at least one copolymer constituting the viscosity improver in accordance with the invention in a proportion of 2 to
• Useful initiators include organic peroxides, hydroperoxides and azo compounds.
• Polymerization of acrylic and methacrylic monomers can take place under a variety of conditions, among which are bulk polymerization, solution polymerization, usually in an organic solvent, preferably mineral oil, emulsion polymerization, suspension polymerization and nonaqueous dispersion techniques.
• Solution polymerization is preferred, especially in mineral oil diluent.
• Molecular weights of the polymers can be controlled employing a number of techniques including choice of initiator, reaction temperature, concentration of monomers and initiator and solvent type. Chain transfer agents can be used.
• Molecular weights can be determined employing standard analytical methods such as gel permeation chromatography (GPC) using a polystyrene standard.
• GPC gel permeation chromatography
• Ionic polymerization techniques are known including cationic and anionic methods; however, cationic methods are generally ineffective for acrylate and methacrylate monomer polymerization.
• Free radical initiation is preferred.
• a typical procedure for preparing the polymers of this invention is to charge at room-temperature about one third of the monomers, diluent, chain transfer agent and a portion of a peroxide initiator.
• the mixture is heated to about 90 °C at which time heating is discontinued and the temperature is allowed to rise exothermically, moderated with cold water cooling, if desired, to about 125 °C.
• cold water cooling is applied, if desired, until the temperature drops to about 90 °C at which time any external cooling is discontinued.
• the materials are held at 90 °C for 1 hour, then four additional portions of initiator are added at hourly intervals. After the final addition of initiator, the reaction mixture is held at 90 °C for 1 hour, stripped then diluted with oil to final concentration and filtered.
• the polymerization conditions in the second case differ from those adopted in the first case in that the concentration of polymerization initiator in it is 1.9 times as high.
• the copolymers thus obtained were referred to as "Viscosity improver A" and “Viscosity improver B” .
• Mn Their number-average molecular masses Mn are 13,000 g/mol and 8800 g/mol and their weight-average molecular masses 26,000 g/mol and 19,000 g/mol, respectively.
• EXAMPLE 2 Copolymers containing short alkyl methacrylates and long alkyl methacrylates A copolymer constituting a viscosity improver is prepared by proceeding as in Example 1.
• the number-average molecular mass Mn of this copolymer is 20,000 g/mol and its weight-average molecular mass 46,000 g/mol, the polydispersity value P being 2.3.
• Viscosity improver E is also obtained by copolymerization of a mixture of
• the copolymer constituting the viscosity improver E exhibits a number- average molecular mass Mn of 12,000 g/mol, a weight-average molecular mass Mn of 23,000 g/mol and a polydispersity value P of 1.9.
• the two copolymers constituting the viscosity improvers D and E according to the prior art exhibit compositions of short alkyl methacrylates lower than 25 % but higher than 0 % .
• Compositions in accordance with the invention were prepared from the viscosity improvers A, B and C.
• compositions of the same type were prepared from the additives D and E.
• an oil of formulation K was employed (corresponding to the lubricating oil which was to be treated), the characteristics of which are: kinematic viscosity at 100°C: 4.8 mm 2 /s
• the final additive concentration in these compositions was: A: 80 % by weight B: 80 % by weight C: 55 % by weight D: 69 % by weight

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Lubricants (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1993
  • 1993-02-04 FR FR9301229A patent/FR2701036B1/fr not_active Expired - Fee Related
• 1994
  • 1994-02-03 MX MX9400882A patent/MX9400882A/es not_active IP Right Cessation
  • 1994-02-04 CA CA002117497A patent/CA2117497A1/en not_active Abandoned
  • 1994-02-04 BR BR9403779A patent/BR9403779A/pt not_active Application Discontinuation
  • 1994-02-04 AU AU61712/94A patent/AU672290B2/en not_active Ceased
  • 1994-02-04 DE DE69432580T patent/DE69432580T2/de not_active Expired - Fee Related
  • 1994-02-04 WO PCT/US1994/001322 patent/WO1994018288A1/en active IP Right Grant
  • 1994-02-04 EP EP94908725A patent/EP0637332B1/de not_active Expired - Lifetime
  • 1994-02-04 JP JP6518267A patent/JPH07509023A/ja not_active Ceased
  • 1994-08-05 KR KR1019940702704A patent/KR950700392A/ko not_active Application Discontinuation

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