CA2117497A1 - Shear stable viscosity improver for lubricating oils - Google Patents
Shear stable viscosity improver for lubricating oilsInfo
- Publication number
- CA2117497A1 CA2117497A1 CA002117497A CA2117497A CA2117497A1 CA 2117497 A1 CA2117497 A1 CA 2117497A1 CA 002117497 A CA002117497 A CA 002117497A CA 2117497 A CA2117497 A CA 2117497A CA 2117497 A1 CA2117497 A1 CA 2117497A1
- Authority
- CA
- Canada
- Prior art keywords
- viscosity
- polymethacrylate
- oil
- lubricating
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Lubricants (AREA)
Abstract
Viscosity improver 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 mm2/s and a VIE of 85 to 100, which 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 %.
Description
.
Title: SHEAR-STABLE VISCOSITY IMPROVER FOR LUBRICATING
OILS
FIELD OF THE INVENTION
The invention relates to a shear-stable viscosity improver for 5 lubricating oils, especially for mineral oils of paraffinic type.
It is also aimed at the ~ based on this improver as well as at lubricating oils ~,Vlll~ illg an effective proportion of the said improver, optionally introduced by means of the said compositions.
BACKGROUND OF THE INVENTION
Viscosity improvers are usually Ill~,lulllol~,~,ular CUllll~vulld~.
The objective of the invention is, above all, to provide a new viscosity improver for lubricating oils, which, besides the characteristics which are uull~llLiul~lly sought after, namely improving the viscosity index of the said 15 oils, exhibits a markedly improved shear strength when compared with improvers that are already known.
It is known that when lubricating oils are placed under extreme use conditions such as are c.l~,uullL~I~d, for example, in gearboxes, differentials and gears of all kinds, especially in motor vehicles, the viscosity improvers 20 hl~,ul~Jul~L~d in these oils are subjected to high shear stresses which causethern to lose their properties at least partially and which r.onc~qn~n~ly lead to losses in viscosity in the lubricating oils.
These losses in viscosity are of two types: they are, on the one hand, temporary losses in viscosity and, on the other hand, irreversible losses in 25 viscosity.
Temporary losses in viscosity are observed during operation; they arise from the aligning of the macromolecular chains which takes place in the shear field, and are reversible.
. .
iblc losses in viscosity are due to scissions of the a~ uol~ ular chains (D.E. Hillman, P.R. Marris, J.I. Paul and D. Pickles - Institute of Petroleum, vol. 008, 1977).
Users of the oils of the kind in question are iulw~a~iuly,ly demanding S and want the hl~ il.lc losses in viscosity, in other words the number of scissions of the ~ll~l~lullloL,~ular chains, to be as small as possible.
To ullalaut~ , the shear strength of a viscosity improver, a strength which is proportionately greater the lower the hlu~ iblc losses in viscosity of a lubricating oil treated with this additive, use is made of the following 10 tests, according to which the said additive, which is ~ sol~"l in a formulating oil, is subjected to high shear stresses with the aid of a shearing tool.
In general, use is made of two types of tools, the use of which then chaldctuli~ the test.
In the first case this is a system of toothed wheels contained by a "FZG" machine and, in the other case, this is a bearing system with r~ .,c~.";. Al needles contained in a "VKA" machine.
In the first case, c.c~ ru,~ lly, reference will be made to the "FZG"
shear strength established by the standard CEC-L-37-T-85 and, in the second, 20 to "VKA" shear strength ~ nnin~d according to standard VW 1437 or CEC PT-6.
Procedure CEC-L-37-T-85'is a test procedure promulgated by the Coordinating European Council (CEC) for the D~ of Pulrollllallce Tests for Lubricants and Engine Fuels. This procedure is used to determine 25 shear stability of polymer-containing oils employing the FZG
(Fu.:~. I,....r,~. 11~, fur Zahnraderund Getriebebau) apparatus. Specifically, the purpose of the test is to determine the permanent viscosity loss of polymer-' CA 2 i 1 74 ~7 . .
containing oils when a sample is rrPrh:~nir:~lly stressed under the testconditions described.
Special gear wheels are run in the lubricant under test in a dip lubrication system at constant speed for a fixed time. The bulk oil S ~ dtUI~ is controlled and the loading of the gear teeth is set according to the procedure.
At the end of the test period the oil is assessed for permanent viscosity loss and the difference in viscosity between the new and sheared oil is used to characterize the shear stability of the oil.
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 t~ IdtUI~ sensor controls the heating system according to the preset ttlll~,ldtUlt~.
The test rig is powered by a two speed electric motor at speeds of approximately 1500/3000 rpm.
A sequence of operations is conducted wherein the test lubricant is subjected to the FZG test for 7.5 minutes each at load stages 1-4 followed by 19.5 hours at load stage 5, all at 90~C. The kinematic viscosity of the test oil is measured and the loss of viscosity is reported as percentage viscosity 10ss .
The "VKA" procedure is'also promulgated by the CEC. This procedure measures 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 ronrhlcion.c tobe drawn on the permanent viscosity loss to be expected under operating ' CA21 1 74q7 conditions, for example, in gear boxes, and which is caused by mrrh~nir~l stress.
The degree of shear stability is the relative viscosity loss (Rv) in % as defined by the following equation:
Relative Viscosity loss Rv = [Vj-Vf]
V x 100%
where:
Vj is the kinematic viscosity of the oil before shear in mm2/sec at 100~C
Vf is the kinematic viscosity of the oil after shear in mm~/sec at lOO~C
The smaller the value Rv the higher the viscosity stability.
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 t~ ,ldLul~ of 60~C during a defined number of motor revolutions (l~e~ ly during a defined running period). The kinematic viscosity of the test oil at 100~C is measured (in dCCOlddll~ with DIN 51562 or equivalent) before and after the test.
The test conditions are given in the table below:
Motor speed 1475 rpm + 25 rpm Lubricant L~ ,.dLul~ 60~C + 1~C
Test oil quantity 40 ml + 0.5 ml Test load 5000 N + 200 N
Test duration A 348000 revolutions (approx. 4 hours) Test duration B 696000 I~,vvluli~ (approx. 8 hours) Test duration C 1740000 revolutions (approx. 20 hours) N.B.: The basis for ~ ' g test duration or the number of 10 1~ volu~ of the motor was a theoretical speed for a~yll~,lu.,ll.,u~ motors of1450 rpm. For motors with speeds that differ from the above, the test durations are to be corrected a~,coldiul~ly.
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 ~l~t~nnin~d for the sample and the relative viscosity change Rv is d~nnin~ d The inventors have observed that the test performed with the aid of the FZG machine or "FZG" test induces at the end of twenty hours about the same hl~ il,le drop in viscosity as the "VKA" test at the end of four hours; in both cases the viscosity changes from an initial value Vj at a given ~elll~)~ldlul~ T to a final viscosity Vf at tne same t~ dLul~ T; the stability to shear is then chdld~ liL~d by the relative drop in viscosity which is given by the formula shown below:
Vj-Vf --x 100%
More particularly, the objective of the invention is to provide a viscosity improver of the kind in question, which is not only capable of '- C A 2 1 1 7 4~7 imparting a VIE of at least 155 to a lubricating oil exhibiting, before ill~,UllJ~Jld~iOII of the said improver, a viscosity at 100~C of 4.8 to 5.5 mm2/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 5 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 Cqlrll1q~ing Viscosity Index from Kinematic Viscosity at 40~C and 100~C, and which is 10 ~ sellt~d by an arbitrary number employed to ~lldld~,t~ the variation in the kinematic viscosity of a petroleum product with t~ ,ldtUI~.
Additives of the kind in question which are already known, which consist of copolymers of esters of methacrylic acid with C, to C,8 alkanols, exhibit a shear strength which, in the above conditions of the "VKA" and 15 ~FZG" tests, is reflected in a relative drop in viscosity of the order of 20%.
SUMMARY OF THE INVENTION
Accordingly, it is surprising that the properties of the viscosity improvers of the kind in question could be improved decisively and especially 20 so that these additives satisfy the conditions referred to above, either by decreasing, to a value equal to zero in a copolymer obtained from esters of methacrylic acid with short alkanors and with long alkanols, the proportion of monomers based on short alkanols, the number-average molecular mass remaining constant, or, in the case of a copolymer of constant composition 25 obtained from monomers consisting of esters of methacrylic acid with short alkanols and with long alkanols, the proportion by weight of short alkyl methacrylates being between 25 % and 75 % and preferably between 30 %
and 50 %, by increasing the number-average molecular mass above a - CA2i 17497 particular critical value which is cl~ld.,t~ Lic for a given copolymer and starting from which the drop in viscosity in the VKA and FZG tests decreases. For purposes of this invention "short" refers to groups containing from I to 4 carbon atoms and "long" refers to groups containing about 10 to S about 18 carbons.
The abu~ critical value of the number-average molecular mass is ~lPf~nninl~d r~llrl i"....l-lly in each case.
It follows that the viscosity improver in ac.,ul.l~ue with the invention is .,I.~ldultli~d in that it is capable of imparting a VIE of at least 155 to a lubricating oil exhibiting, before h~,ulluul~tiull of the said improver, a viscosity at 100~C of 4.8 to 5.5 mm2/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 lll~,Lh~l~,lyliC acid with a long alkanol, more particularly C1o to C,8 and preferably C" to C~5, the number-average molecular mass of this copolymer being from 7000 to 15,000 g/mol and, preferably, from 8500 to 13,500 g/mol, or of a copolymer essentially obtained by COpO~ dtiUll from at least one of the monomers of the group consisting of the esters of ~ h~l~,lylil acid with a long alkanol, more pdl~i-,uldlly C1o to C18 and preferably C" to C~5, and of at least one of the monomers of the group consisting of the esters of lll~h~lylic acid with a short alkanol, more particularly Cl to C4, the weight proportion of short alkyl m~ ,lyldtts being between 25 % and 75 % and preferably between 30 % and 50 %, the number-average molecular mass of this copolymer being higher for a constant C~ 2 i l 74q7 Co~ )O~iliull ûf the said copolymer than the critical value starting from which the drop in viscosity in the VKA and FZG tests decreases.
According to an advallL~ Ju~ .. "1.~1;.. 1 the ab~.- .. li.:.,,. ~
viscosity improver consists of a copolymer essentially obtained by S 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"
to C,5 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 Cl to C4 short alkanol, the critical value of the number-average molecular mass of this copolymer being from 27,000 to 32,000 g/mol.
The copolymers ~ ; ,.g the viscosity improvers in acu~,lddl.~,e with the invention can be employed as they are, the quantity of copolymers used cull."l~.Jlldillg 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.
It is convenient, however, to use them in the form of a composition 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. The mineral oil may be the same as the lubricating oil which is to be treated. The composition in accolddllue 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 dl,colddllce 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.
CA2i 1 74~7 Synthetic lubricating oils include hydlu~ lJull oils, halo-substituted hydlucalbull oils, alkylene oxide polymers, esters of carboxylic acids and polyols, esters of poly~,dll/v~ylic acids and alcohols, esters of phosphorus-containing acids, polymeric L~ldhydl~ruldl~ silicone-based oils and mixtures 5 thereof.
Specific examples of oils of lubricating viscosity are described in U.S.
Patent No. 4,326,972 and European Patent I~l,li.,dlioll 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.
10 Brock, "Lubricant Base Oils", Lubrication F..~,i".. .i.,g. volume 43, pages 184-185, March, 1987. This article is herein iuluul,uuldL~d by reference for its disclosures relating to lubricating oils. A ~ rriptir,n 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 hl~,(JI,uuldl~d by reference for its 15 disclosure to oils of lubricating viscosity.
The lubricating oil composition in a~,~,uldallc~; with the invention is characterized in that it comprises at least one copolymer uull~LiLuLill~, the viscosity improver in a~,~,ul.ldllc~ with the invention in a proportion of 2 to 40 %, preferably of 3 to 30 %, and, still more preferably, of 4 to 25 % by 20 weight of the mass of lubricating oil to be treated.
To prepare the copolymers cul~LiLuLillg the viscosity improvers in accùlllallce with the invention it is~possible to make use of the conventional methods of radical copolylll~ ;dLi~ll in solution in oil.
Such methods are described in the work "Encyclopedia of Polymer 25 Science and Ellgil-~,~.i.lg" (H.F. Mark, N.M. Bikales, C.G. Overberger and G. Menges), 2nd edition (1988), published by Wiley IIlL~l~ci~ ,e.
~A2t 1 7497 .
These methods include free-radical initiated pOly~ .i~lio.. employing azo ~,uu-~ u--d~ or peroxides. Also described therein are ~ . h~ 1 and radiation initiated methods.
Useful initiators include organic peroxides, hyd-u~ idcs and azo S ~ Jllllll~
Polymerization of acrylic and ll~,lL~ yli~, monomers can take place under a variety of conditions, among which are bulk pOlylll~ aliull, solution poly.l.~ ;l", usually in an organic solvent, preferably mineral oil, emulsion polymPri7 ~ m suspension polyl.~ Li~J.. and nonaqueous 10 dispersion te(~hni11lPc 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 hlll}J~Id~UI~, concentration of monomers and initiator and solvent type. Chain transfer 15 agents can be used.
Molecular weights can be d~;L~IIlliuled employing standard analytical methods such as gel permeation chromatography (GPC) using a polystyrene standard.
Ionic poly.ll~ ion techniques are known including cationic and 20 anionic methods; however, cationic methods are generally ineffective for acrylate and Ill~ lyldL~ monomer ~olylll~ ioll.
Free radical initiation is preferred.
Because acrylic polylll~ d~ions are usually ~c..",l.~ d by liberation of cullaid~l~lblc heat, care must be taken to avoid uncontrolled reaction.
25 Te.l~ldlul~s can be controlled by using reactors with cooling jackets, controlling rates of addition and use of reaction solvents.
A typical procedure for preparing the polymers of this invention is to charge at room~ ,ld~ul~ about one third of the monomers, diluent, chain CA21 1 74~7 transfer agent and a portion of a peroxide initiator. The mixture is heated to about 90~C at which time heating is ~ ..f;~ rd and the ~ )...dLUlt~ is allowed to rise ~ h~nni~ lly, moderated with cold water cooling, if desired, to about 125~C. At this i , ~, the remaining two-thirds of monomer, S additional oil, chain transfer agent and a portion of initiator are added overabout 1.5 hours. During this time cold water cooling is applicd, if desired, until the L~ ldLUlt~ drops to about 90~C at which time any external cooling is .1;~ . .1 After monomer addition is completed the materials are held at 90~C for I hour, then four additional portions of initiator are added at 10 hourly intervals. After the final addition of initiator, the reaction mixture is held at 90~C for I hour, stripped then diluted with oil to final cr~nr~mr~ion and filtered.
Using these methods, a certain number of copolymers ..~ i"g the viscosity improvers in accul-lallu~ with the invention have been prepared in 15 oil solution by way of n~.,li,il;.,~, examples illustrating advdllL,.~;~,uu~
~ h~.l;", .~ of the invention.
EXAMPLE 1: Copolvmers ~ no short alkyl '' ~
Two copolymers ~u~ lg a viscosity improver in ac.,ul-ldllce with the invention are prepared by making use of the methods described above.
To do this, two mixtures of esters of Ill~Lha~,lylic acid with C~l to C15 alkanols are polymerized separately; in this case the p.,.~llLag~ by weight of each of the esters based on the' alkanols in the mixture of esters were approximately CII/C~2/CB/CI4/CI5 = 1%120%130%128%121 %byweigb~,inboth cases.
The pOlylllt;li~d~iull conditions in the second case differ from those adopted in the first case in that the ~UncculLl dLiUII of pOlylll1l i dLiUll initiator in it is 1.9 times as high.
-Il-- CA~ 17~7 The copolymers thus obtained were referred to as ~Viscosity improver A" and ~Viscosity improver B".
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 S 19,000 g/mol, respectively.
Their pOIy-lia~ ai~y values P (ratio of Mw/Mn) are 2.0 and 2.2 respectively.
EXAMPLE 2: Copolvmers ~ short alkyl '' ~ ~- ' and lone alkyl ' ~ Id~a A copolymer ~."~ ;.,g a viscosity improver is prepared by cccJh.g as in Example 1.
To do this, a mixture of 20 parts by weight of ester of methacrylic acid with methanol, of 20 parts by weight of ester of ~llcJ~ ,lylic acid with butanoland of 60 parts by weight of ester of ~ ,Jl~l~,-yli~ acid with a mixture of C~, to Cl5 alkanols is copolymerized, the p~ lL~gCa by weight of the alkanols in the alkanol mixture being Cll/ C12/ C~3/ C14/ C15 = 1 % /20 % /30 % /28 % /21 %.
The copolymer thus obtained was referred to as "Viscosity improver C".
Its number-average molecular mass Mn is 30,000 g/mol, its weight-average molecular mass Mw 76,000 g/mol and its polyJialJclaiLy value P 2.5.
In the case of this copolymerthe critical molecular mass Mn determined c~ clhll~,llLdlly is 28,000 g/mol.
EXAMPLE 3: C~ . ~ of properties Two additives according to the prior art are used for the purpose of CUIIIIJ~I ia~
CA 2 i 1 74 97 The first of these additives ("Viscosity improver D") is obtained by copolyllleli~aLiull of a mixture of - 15 parts by weight of esters of ~ lic acid with methanol, - 85 parts by weight of ester of lll~Lh~..,lylic acid with a mixhure of S Cl,-C,5 aLkanols, the percentages by weight of the alkanols in this mixhure being Cll/CI2/CI3/C~4/C15 = I %1~;)%130%128%121 %.
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 polydia~ y value P being 2.3.
The second of these additives (nViscosity improver E") is also obtained by copolymerization of a mixture of - 15 parts by weight of ester of methacrylic acid with methanol, - 85 parts by weight of ester of methacrylic acid with a mixture of C~-C~5 alkanols, the percentages by weight of the alkanols in this mixture being Cll/C,~/C13/C14/C15 = 1 %120%130%128%121 %
but the polymerization conditions differ from those adopted for the viscosity improver D in that the COllC~ ldLiull of pOIylll~ dLiUll initiator is 1.5 times as high.
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 pulydi~,u~l~iLy value P of 1.9.
In contrast with the viscosity improvers in dl,CUlddllle with the invention, the two copolymers con~tih~ling the viscosity improvers D and E
according to the prior art exhibit compositions of short alkyl lll~Lh~
lower than 25 % but higher than 0 %.
CA21 1 74~7 .
C'""'l~~'~ m acculd... e witb the inventiûn were preparcd from the viscosity improvers A, B and C.
F~ IOIC, ~,UllllJO~i~iUll~ of tbe same type were prepared from the additives D and E.
S In the case of the additives A and B an oil of formulation K was employed (collc~l~ulldillg to the lubricating oil which was to be treated), the ch~l~ctcli~ics of which are:
- kinematic viscosity at 100~C: 4.8 mm2/5 - VIE: 90.
In the case of additive C an oil of formulation M was employed (. ullc~vll~lhlg to the lubricating oil which was to be treated), the characteristics of which are:
- kinematic viscosity at 100~C: 5.3 mm2/s - VIE: 100.
In the case of additives D and E, oil K was employed.
The final additive concentration in these fomp~ ion~ was:
A: 80 % by weight B: 80 % by weight C: 55 % by weight D: 69 % by weight E: 69 % by weight.
The abu.--"--,li--n~ ~,UIII~)O~i~iUlla containing the additives A to E
lc~l~c~ ly were hlcol~ul.~icd into the lubricating oils to be treated K and M
and the following were tben measured on the oils thus treated:
- the kinematic viscosity at 100~C for A to E
- the kinematic viscosity at 40~C for B and C
- the value of VIE
and the VKA and FZG tests were performed.
CA 2 i 1 7 4q7 The values found are assembled in the table which follows, together with the final ~,UIlC~llL.dtiol. of viscosity irnprover for cach case in the lubricating oil treated.
TABLE
Viscositv Concentration Kinematic Kmematic VIE Drop m relative improver (%) in the oil viscosity atviscositv at viscosity ~%) to be treatetl IOO'C 40~C
(mm2/s) (mm21s) VKA FZG
A 21.0 14.1 165 12.2 0 Invention B 28.4 13.9 89.1 160 4.8 C 7.9 9.1 47.7 175 9.6 D 20.0 15.0 175 20.1 Prior art E 20.2 14.1 170 18.1 When the results assembled in this table are examined, it is seen that the 15 viscosity improvers of the prior art do not meet the conditions required in the case of the additives in a~,-,ulddll~e with the invention insofar as the shear strength is concemed.
Title: SHEAR-STABLE VISCOSITY IMPROVER FOR LUBRICATING
OILS
FIELD OF THE INVENTION
The invention relates to a shear-stable viscosity improver for 5 lubricating oils, especially for mineral oils of paraffinic type.
It is also aimed at the ~ based on this improver as well as at lubricating oils ~,Vlll~ illg an effective proportion of the said improver, optionally introduced by means of the said compositions.
BACKGROUND OF THE INVENTION
Viscosity improvers are usually Ill~,lulllol~,~,ular CUllll~vulld~.
The objective of the invention is, above all, to provide a new viscosity improver for lubricating oils, which, besides the characteristics which are uull~llLiul~lly sought after, namely improving the viscosity index of the said 15 oils, exhibits a markedly improved shear strength when compared with improvers that are already known.
It is known that when lubricating oils are placed under extreme use conditions such as are c.l~,uullL~I~d, for example, in gearboxes, differentials and gears of all kinds, especially in motor vehicles, the viscosity improvers 20 hl~,ul~Jul~L~d in these oils are subjected to high shear stresses which causethern to lose their properties at least partially and which r.onc~qn~n~ly lead to losses in viscosity in the lubricating oils.
These losses in viscosity are of two types: they are, on the one hand, temporary losses in viscosity and, on the other hand, irreversible losses in 25 viscosity.
Temporary losses in viscosity are observed during operation; they arise from the aligning of the macromolecular chains which takes place in the shear field, and are reversible.
. .
iblc losses in viscosity are due to scissions of the a~ uol~ ular chains (D.E. Hillman, P.R. Marris, J.I. Paul and D. Pickles - Institute of Petroleum, vol. 008, 1977).
Users of the oils of the kind in question are iulw~a~iuly,ly demanding S and want the hl~ il.lc losses in viscosity, in other words the number of scissions of the ~ll~l~lullloL,~ular chains, to be as small as possible.
To ullalaut~ , the shear strength of a viscosity improver, a strength which is proportionately greater the lower the hlu~ iblc losses in viscosity of a lubricating oil treated with this additive, use is made of the following 10 tests, according to which the said additive, which is ~ sol~"l in a formulating oil, is subjected to high shear stresses with the aid of a shearing tool.
In general, use is made of two types of tools, the use of which then chaldctuli~ the test.
In the first case this is a system of toothed wheels contained by a "FZG" machine and, in the other case, this is a bearing system with r~ .,c~.";. Al needles contained in a "VKA" machine.
In the first case, c.c~ ru,~ lly, reference will be made to the "FZG"
shear strength established by the standard CEC-L-37-T-85 and, in the second, 20 to "VKA" shear strength ~ nnin~d according to standard VW 1437 or CEC PT-6.
Procedure CEC-L-37-T-85'is a test procedure promulgated by the Coordinating European Council (CEC) for the D~ of Pulrollllallce Tests for Lubricants and Engine Fuels. This procedure is used to determine 25 shear stability of polymer-containing oils employing the FZG
(Fu.:~. I,....r,~. 11~, fur Zahnraderund Getriebebau) apparatus. Specifically, the purpose of the test is to determine the permanent viscosity loss of polymer-' CA 2 i 1 74 ~7 . .
containing oils when a sample is rrPrh:~nir:~lly stressed under the testconditions described.
Special gear wheels are run in the lubricant under test in a dip lubrication system at constant speed for a fixed time. The bulk oil S ~ dtUI~ is controlled and the loading of the gear teeth is set according to the procedure.
At the end of the test period the oil is assessed for permanent viscosity loss and the difference in viscosity between the new and sheared oil is used to characterize the shear stability of the oil.
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 t~ IdtUI~ sensor controls the heating system according to the preset ttlll~,ldtUlt~.
The test rig is powered by a two speed electric motor at speeds of approximately 1500/3000 rpm.
A sequence of operations is conducted wherein the test lubricant is subjected to the FZG test for 7.5 minutes each at load stages 1-4 followed by 19.5 hours at load stage 5, all at 90~C. The kinematic viscosity of the test oil is measured and the loss of viscosity is reported as percentage viscosity 10ss .
The "VKA" procedure is'also promulgated by the CEC. This procedure measures 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 ronrhlcion.c tobe drawn on the permanent viscosity loss to be expected under operating ' CA21 1 74q7 conditions, for example, in gear boxes, and which is caused by mrrh~nir~l stress.
The degree of shear stability is the relative viscosity loss (Rv) in % as defined by the following equation:
Relative Viscosity loss Rv = [Vj-Vf]
V x 100%
where:
Vj is the kinematic viscosity of the oil before shear in mm2/sec at 100~C
Vf is the kinematic viscosity of the oil after shear in mm~/sec at lOO~C
The smaller the value Rv the higher the viscosity stability.
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 t~ ,ldLul~ of 60~C during a defined number of motor revolutions (l~e~ ly during a defined running period). The kinematic viscosity of the test oil at 100~C is measured (in dCCOlddll~ with DIN 51562 or equivalent) before and after the test.
The test conditions are given in the table below:
Motor speed 1475 rpm + 25 rpm Lubricant L~ ,.dLul~ 60~C + 1~C
Test oil quantity 40 ml + 0.5 ml Test load 5000 N + 200 N
Test duration A 348000 revolutions (approx. 4 hours) Test duration B 696000 I~,vvluli~ (approx. 8 hours) Test duration C 1740000 revolutions (approx. 20 hours) N.B.: The basis for ~ ' g test duration or the number of 10 1~ volu~ of the motor was a theoretical speed for a~yll~,lu.,ll.,u~ motors of1450 rpm. For motors with speeds that differ from the above, the test durations are to be corrected a~,coldiul~ly.
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 ~l~t~nnin~d for the sample and the relative viscosity change Rv is d~nnin~ d The inventors have observed that the test performed with the aid of the FZG machine or "FZG" test induces at the end of twenty hours about the same hl~ il,le drop in viscosity as the "VKA" test at the end of four hours; in both cases the viscosity changes from an initial value Vj at a given ~elll~)~ldlul~ T to a final viscosity Vf at tne same t~ dLul~ T; the stability to shear is then chdld~ liL~d by the relative drop in viscosity which is given by the formula shown below:
Vj-Vf --x 100%
More particularly, the objective of the invention is to provide a viscosity improver of the kind in question, which is not only capable of '- C A 2 1 1 7 4~7 imparting a VIE of at least 155 to a lubricating oil exhibiting, before ill~,UllJ~Jld~iOII of the said improver, a viscosity at 100~C of 4.8 to 5.5 mm2/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 5 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 Cqlrll1q~ing Viscosity Index from Kinematic Viscosity at 40~C and 100~C, and which is 10 ~ sellt~d by an arbitrary number employed to ~lldld~,t~ the variation in the kinematic viscosity of a petroleum product with t~ ,ldtUI~.
Additives of the kind in question which are already known, which consist of copolymers of esters of methacrylic acid with C, to C,8 alkanols, exhibit a shear strength which, in the above conditions of the "VKA" and 15 ~FZG" tests, is reflected in a relative drop in viscosity of the order of 20%.
SUMMARY OF THE INVENTION
Accordingly, it is surprising that the properties of the viscosity improvers of the kind in question could be improved decisively and especially 20 so that these additives satisfy the conditions referred to above, either by decreasing, to a value equal to zero in a copolymer obtained from esters of methacrylic acid with short alkanors and with long alkanols, the proportion of monomers based on short alkanols, the number-average molecular mass remaining constant, or, in the case of a copolymer of constant composition 25 obtained from monomers consisting of esters of methacrylic acid with short alkanols and with long alkanols, the proportion by weight of short alkyl methacrylates being between 25 % and 75 % and preferably between 30 %
and 50 %, by increasing the number-average molecular mass above a - CA2i 17497 particular critical value which is cl~ld.,t~ Lic for a given copolymer and starting from which the drop in viscosity in the VKA and FZG tests decreases. For purposes of this invention "short" refers to groups containing from I to 4 carbon atoms and "long" refers to groups containing about 10 to S about 18 carbons.
The abu~ critical value of the number-average molecular mass is ~lPf~nninl~d r~llrl i"....l-lly in each case.
It follows that the viscosity improver in ac.,ul.l~ue with the invention is .,I.~ldultli~d in that it is capable of imparting a VIE of at least 155 to a lubricating oil exhibiting, before h~,ulluul~tiull of the said improver, a viscosity at 100~C of 4.8 to 5.5 mm2/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 lll~,Lh~l~,lyliC acid with a long alkanol, more particularly C1o to C,8 and preferably C" to C~5, the number-average molecular mass of this copolymer being from 7000 to 15,000 g/mol and, preferably, from 8500 to 13,500 g/mol, or of a copolymer essentially obtained by COpO~ dtiUll from at least one of the monomers of the group consisting of the esters of ~ h~l~,lylil acid with a long alkanol, more pdl~i-,uldlly C1o to C18 and preferably C" to C~5, and of at least one of the monomers of the group consisting of the esters of lll~h~lylic acid with a short alkanol, more particularly Cl to C4, the weight proportion of short alkyl m~ ,lyldtts being between 25 % and 75 % and preferably between 30 % and 50 %, the number-average molecular mass of this copolymer being higher for a constant C~ 2 i l 74q7 Co~ )O~iliull ûf the said copolymer than the critical value starting from which the drop in viscosity in the VKA and FZG tests decreases.
According to an advallL~ Ju~ .. "1.~1;.. 1 the ab~.- .. li.:.,,. ~
viscosity improver consists of a copolymer essentially obtained by S 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"
to C,5 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 Cl to C4 short alkanol, the critical value of the number-average molecular mass of this copolymer being from 27,000 to 32,000 g/mol.
The copolymers ~ ; ,.g the viscosity improvers in acu~,lddl.~,e with the invention can be employed as they are, the quantity of copolymers used cull."l~.Jlldillg 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.
It is convenient, however, to use them in the form of a composition 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. The mineral oil may be the same as the lubricating oil which is to be treated. The composition in accolddllue 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 dl,colddllce 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.
CA2i 1 74~7 Synthetic lubricating oils include hydlu~ lJull oils, halo-substituted hydlucalbull oils, alkylene oxide polymers, esters of carboxylic acids and polyols, esters of poly~,dll/v~ylic acids and alcohols, esters of phosphorus-containing acids, polymeric L~ldhydl~ruldl~ silicone-based oils and mixtures 5 thereof.
Specific examples of oils of lubricating viscosity are described in U.S.
Patent No. 4,326,972 and European Patent I~l,li.,dlioll 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.
10 Brock, "Lubricant Base Oils", Lubrication F..~,i".. .i.,g. volume 43, pages 184-185, March, 1987. This article is herein iuluul,uuldL~d by reference for its disclosures relating to lubricating oils. A ~ rriptir,n 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 hl~,(JI,uuldl~d by reference for its 15 disclosure to oils of lubricating viscosity.
The lubricating oil composition in a~,~,uldallc~; with the invention is characterized in that it comprises at least one copolymer uull~LiLuLill~, the viscosity improver in a~,~,ul.ldllc~ with the invention in a proportion of 2 to 40 %, preferably of 3 to 30 %, and, still more preferably, of 4 to 25 % by 20 weight of the mass of lubricating oil to be treated.
To prepare the copolymers cul~LiLuLillg the viscosity improvers in accùlllallce with the invention it is~possible to make use of the conventional methods of radical copolylll~ ;dLi~ll in solution in oil.
Such methods are described in the work "Encyclopedia of Polymer 25 Science and Ellgil-~,~.i.lg" (H.F. Mark, N.M. Bikales, C.G. Overberger and G. Menges), 2nd edition (1988), published by Wiley IIlL~l~ci~ ,e.
~A2t 1 7497 .
These methods include free-radical initiated pOly~ .i~lio.. employing azo ~,uu-~ u--d~ or peroxides. Also described therein are ~ . h~ 1 and radiation initiated methods.
Useful initiators include organic peroxides, hyd-u~ idcs and azo S ~ Jllllll~
Polymerization of acrylic and ll~,lL~ yli~, monomers can take place under a variety of conditions, among which are bulk pOlylll~ aliull, solution poly.l.~ ;l", usually in an organic solvent, preferably mineral oil, emulsion polymPri7 ~ m suspension polyl.~ Li~J.. and nonaqueous 10 dispersion te(~hni11lPc 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 hlll}J~Id~UI~, concentration of monomers and initiator and solvent type. Chain transfer 15 agents can be used.
Molecular weights can be d~;L~IIlliuled employing standard analytical methods such as gel permeation chromatography (GPC) using a polystyrene standard.
Ionic poly.ll~ ion techniques are known including cationic and 20 anionic methods; however, cationic methods are generally ineffective for acrylate and Ill~ lyldL~ monomer ~olylll~ ioll.
Free radical initiation is preferred.
Because acrylic polylll~ d~ions are usually ~c..",l.~ d by liberation of cullaid~l~lblc heat, care must be taken to avoid uncontrolled reaction.
25 Te.l~ldlul~s can be controlled by using reactors with cooling jackets, controlling rates of addition and use of reaction solvents.
A typical procedure for preparing the polymers of this invention is to charge at room~ ,ld~ul~ about one third of the monomers, diluent, chain CA21 1 74~7 transfer agent and a portion of a peroxide initiator. The mixture is heated to about 90~C at which time heating is ~ ..f;~ rd and the ~ )...dLUlt~ is allowed to rise ~ h~nni~ lly, moderated with cold water cooling, if desired, to about 125~C. At this i , ~, the remaining two-thirds of monomer, S additional oil, chain transfer agent and a portion of initiator are added overabout 1.5 hours. During this time cold water cooling is applicd, if desired, until the L~ ldLUlt~ drops to about 90~C at which time any external cooling is .1;~ . .1 After monomer addition is completed the materials are held at 90~C for I hour, then four additional portions of initiator are added at 10 hourly intervals. After the final addition of initiator, the reaction mixture is held at 90~C for I hour, stripped then diluted with oil to final cr~nr~mr~ion and filtered.
Using these methods, a certain number of copolymers ..~ i"g the viscosity improvers in accul-lallu~ with the invention have been prepared in 15 oil solution by way of n~.,li,il;.,~, examples illustrating advdllL,.~;~,uu~
~ h~.l;", .~ of the invention.
EXAMPLE 1: Copolvmers ~ no short alkyl '' ~
Two copolymers ~u~ lg a viscosity improver in ac.,ul-ldllce with the invention are prepared by making use of the methods described above.
To do this, two mixtures of esters of Ill~Lha~,lylic acid with C~l to C15 alkanols are polymerized separately; in this case the p.,.~llLag~ by weight of each of the esters based on the' alkanols in the mixture of esters were approximately CII/C~2/CB/CI4/CI5 = 1%120%130%128%121 %byweigb~,inboth cases.
The pOlylllt;li~d~iull conditions in the second case differ from those adopted in the first case in that the ~UncculLl dLiUII of pOlylll1l i dLiUll initiator in it is 1.9 times as high.
-Il-- CA~ 17~7 The copolymers thus obtained were referred to as ~Viscosity improver A" and ~Viscosity improver B".
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 S 19,000 g/mol, respectively.
Their pOIy-lia~ ai~y values P (ratio of Mw/Mn) are 2.0 and 2.2 respectively.
EXAMPLE 2: Copolvmers ~ short alkyl '' ~ ~- ' and lone alkyl ' ~ Id~a A copolymer ~."~ ;.,g a viscosity improver is prepared by cccJh.g as in Example 1.
To do this, a mixture of 20 parts by weight of ester of methacrylic acid with methanol, of 20 parts by weight of ester of ~llcJ~ ,lylic acid with butanoland of 60 parts by weight of ester of ~ ,Jl~l~,-yli~ acid with a mixture of C~, to Cl5 alkanols is copolymerized, the p~ lL~gCa by weight of the alkanols in the alkanol mixture being Cll/ C12/ C~3/ C14/ C15 = 1 % /20 % /30 % /28 % /21 %.
The copolymer thus obtained was referred to as "Viscosity improver C".
Its number-average molecular mass Mn is 30,000 g/mol, its weight-average molecular mass Mw 76,000 g/mol and its polyJialJclaiLy value P 2.5.
In the case of this copolymerthe critical molecular mass Mn determined c~ clhll~,llLdlly is 28,000 g/mol.
EXAMPLE 3: C~ . ~ of properties Two additives according to the prior art are used for the purpose of CUIIIIJ~I ia~
CA 2 i 1 74 97 The first of these additives ("Viscosity improver D") is obtained by copolyllleli~aLiull of a mixture of - 15 parts by weight of esters of ~ lic acid with methanol, - 85 parts by weight of ester of lll~Lh~..,lylic acid with a mixhure of S Cl,-C,5 aLkanols, the percentages by weight of the alkanols in this mixhure being Cll/CI2/CI3/C~4/C15 = I %1~;)%130%128%121 %.
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 polydia~ y value P being 2.3.
The second of these additives (nViscosity improver E") is also obtained by copolymerization of a mixture of - 15 parts by weight of ester of methacrylic acid with methanol, - 85 parts by weight of ester of methacrylic acid with a mixture of C~-C~5 alkanols, the percentages by weight of the alkanols in this mixture being Cll/C,~/C13/C14/C15 = 1 %120%130%128%121 %
but the polymerization conditions differ from those adopted for the viscosity improver D in that the COllC~ ldLiull of pOIylll~ dLiUll initiator is 1.5 times as high.
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 pulydi~,u~l~iLy value P of 1.9.
In contrast with the viscosity improvers in dl,CUlddllle with the invention, the two copolymers con~tih~ling the viscosity improvers D and E
according to the prior art exhibit compositions of short alkyl lll~Lh~
lower than 25 % but higher than 0 %.
CA21 1 74~7 .
C'""'l~~'~ m acculd... e witb the inventiûn were preparcd from the viscosity improvers A, B and C.
F~ IOIC, ~,UllllJO~i~iUll~ of tbe same type were prepared from the additives D and E.
S In the case of the additives A and B an oil of formulation K was employed (collc~l~ulldillg to the lubricating oil which was to be treated), the ch~l~ctcli~ics of which are:
- kinematic viscosity at 100~C: 4.8 mm2/5 - VIE: 90.
In the case of additive C an oil of formulation M was employed (. ullc~vll~lhlg to the lubricating oil which was to be treated), the characteristics of which are:
- kinematic viscosity at 100~C: 5.3 mm2/s - VIE: 100.
In the case of additives D and E, oil K was employed.
The final additive concentration in these fomp~ ion~ was:
A: 80 % by weight B: 80 % by weight C: 55 % by weight D: 69 % by weight E: 69 % by weight.
The abu.--"--,li--n~ ~,UIII~)O~i~iUlla containing the additives A to E
lc~l~c~ ly were hlcol~ul.~icd into the lubricating oils to be treated K and M
and the following were tben measured on the oils thus treated:
- the kinematic viscosity at 100~C for A to E
- the kinematic viscosity at 40~C for B and C
- the value of VIE
and the VKA and FZG tests were performed.
CA 2 i 1 7 4q7 The values found are assembled in the table which follows, together with the final ~,UIlC~llL.dtiol. of viscosity irnprover for cach case in the lubricating oil treated.
TABLE
Viscositv Concentration Kinematic Kmematic VIE Drop m relative improver (%) in the oil viscosity atviscositv at viscosity ~%) to be treatetl IOO'C 40~C
(mm2/s) (mm21s) VKA FZG
A 21.0 14.1 165 12.2 0 Invention B 28.4 13.9 89.1 160 4.8 C 7.9 9.1 47.7 175 9.6 D 20.0 15.0 175 20.1 Prior art E 20.2 14.1 170 18.1 When the results assembled in this table are examined, it is seen that the 15 viscosity improvers of the prior art do not meet the conditions required in the case of the additives in a~,-,ulddll~e with the invention insofar as the shear strength is concemed.
Claims (23)
1. A shear stable polymethacrylate viscosity improver for lubricating oils wherein each ester moiety of said polymethacrylate contains, independently, from about 10 to about 18 carbon atoms and the number average molecular mass ranges from about 7000 to about 15000 grams per mole.
2. The polymethacrylate of claim 1 wherein each ester moiety of said polymethacrylate contains, independently, from about 11 to about 15 carbon atoms.
3. The polymethacrylate of claim 1 wherein the number average molecular mass ranges from about 8500 to about 13500.
4. A shear stable polymethacrylate viscosity improver for lubricating oils derived from alkyl methacrylate monomers wherein from about 25% to about 75% by weight of said monomers are C1-4 alkyl methacrylates and the balance are C10-18 alkyl methacrylates.
5. The polymethacrylate of claim 4 wherein the number average molecular mass is greater than the number average molecular mass of a corresponding polymethacrylate where the rate of change of drop in viscosity of a lubricating oil containing same which is subjected to shearing begins to decrease.
6. The polymethacrylate viscosity improver of claim 4 wherein from about 55% to about 65% by weight of said monomers are C11-15 alkyl methacrylates and from about 45% to about 35% by weight are C1-4 alkyl methacrylates and the number average molecular mass ranges from about 27000 to about 32000 grams per mole.
7. Viscosity improver according to claim 4 characterized in that it consists of a copolymer obtained from 60 percent by weight of the esters of methacrylic acid with C11 to C15 long alkanols, 20 parts by weight of each of the esters of methacrylic acid with, on the one hand, methanol and, on the other hand, butanol, the number-average molecular mass of this copolymer being about 30,000 g/mol and its shear strength such that the relative drop in viscosity in the VKA test is 9.6.
8. Viscosity improver according to claim 1, characterized in that it consists of a copolymer obtained by polymerization from monomers of the group consisting of the esters of methacrylic acid with C11 to C15 long alkanols, the number-average molecular mass of this copolymer being 13,000 g/mol and its shear strength such that the relative drop in viscosity in the VKAtest is 12.2.
9. Viscosity improver according to claim 1, characterized in that it consists of a copolymer obtained by polymerization from monomers of the group consisting of the esters of methacrylic acid with C11 to C15 long alkanols, the number-average molecular mass of this copolymer being 8,800 g/mol and its shear strength such that the relative drop in viscosity in the VKAtest is 4.8.
10. A composition comprising from about 30% to about 90% by weight of a polymethacrylate according to claim 1 and the balance comprising a normally liquid organic diluent.
11. A composition comprising from about 30% to about 90% by weight of a polymethacrylate according to claim 4 and the balance comprising a normally liquid organic diluent.
12. A lubricating oil composition comprising an oil of lubricating viscosity and from about 2% to about 40% by weight of the polymethacrylate of claim 1.
13. A lubricating oil composition comprising an oil of lubricating viscosity and from about 2% to about 40% by weight of the polymethacrylate of claim 4.
14. The lubricating oil composition of claim 12 wherein the oil of lubricating viscosity is a mineral oil.
15. The lubricating oil composition of claim 14 wherein the mineral oil is a paraffinic oil.
16. The lubricating oil composition of claim 12 wherein the oil of lubricating viscosity has a viscosity at 100°C of 4.8 to 5.5 mm /sec and a viscosity index of about 85 to about 100.
17. The lubricating oil composition of claim 13 wherein the oil of lubricating viscosity is a mineral oil.
18. The lubricating oil composition of claim 17 wherein the mineral oil is a paraffinic oil.
19. The lubricating oil composition of claim 13 wherein the oil of lubricating viscosity has a viscosity at 100° C of 4.8 to 5.5 mm /sec and a viscosity index of from about 85 to about 100.
20. A method comprising the step of adding to an oil of lubricating viscosity from about 2% to about 40% by weight of the polymethacrylate of claim 1.
21. A method comprising the step of adding to an oil of lubricating viscosity from about 2% to about 40% by weight of the polymethacrylate of claim 4.
22. A polymethacrylate prepared by the process comprising reacting in an organic diluent in the presence of a free radical initiator at least one monomer selected from the group consisting of C11-18 alkyl methacrylates.
23. A polymethacrylate prepared by the process comprising reacting in an organic diluent in the presence of a free radical initiator at least one monomer selected from the group consisting of C1-4 alkyl methacrylates, and at least one other monomer selected from the group consisting of C10-18 alkyl methacrylates.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR93/01229 | 1993-02-04 | ||
| FR9301229A FR2701036B1 (en) | 1993-02-04 | 1993-02-04 | Additive with shear stable viscosity for lubricating oils. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2117497A1 true CA2117497A1 (en) | 1994-10-04 |
Family
ID=9443722
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002117497A Abandoned CA2117497A1 (en) | 1993-02-04 | 1994-02-04 | Shear stable viscosity improver for lubricating oils |
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| Country | Link |
|---|---|
| EP (1) | EP0637332B1 (en) |
| JP (1) | JPH07509023A (en) |
| KR (1) | KR950700392A (en) |
| AU (1) | AU672290B2 (en) |
| BR (1) | BR9403779A (en) |
| CA (1) | CA2117497A1 (en) |
| DE (1) | DE69432580T2 (en) |
| FR (1) | FR2701036B1 (en) |
| MX (1) | MX9400882A (en) |
| WO (1) | WO1994018288A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5817606A (en) * | 1996-08-08 | 1998-10-06 | Rohm And Haas Company | Viscosity index improving additives for phosphate ester-containing hydraulic fluids |
| US6124249A (en) | 1998-12-22 | 2000-09-26 | The Lubrizol Corporation | Viscosity improvers for lubricating oil compositions |
| CA2261458C (en) * | 1998-02-18 | 2009-02-10 | The Lubrizol Corporation | Viscosity improvers for lubricating oil compositions |
| DE102004021778A1 (en) * | 2004-04-30 | 2005-12-08 | Rohmax Additives Gmbh | Use of polyalkyl (meth) acrylates in lubricating oil compositions |
| JP5246992B2 (en) * | 2005-06-21 | 2013-07-24 | 三洋化成工業株式会社 | Viscosity index improver and lubricating oil composition |
| DE102005041528A1 (en) | 2005-08-31 | 2007-03-01 | Rohmax Additives Gmbh | Multi-arm star-shaped polymer for use as lubricating oil additive, e.g. viscosity modifier or dispersant, has at least three arms containing units derived from esters of higher alkanols and unsaturated carboxylic acids |
| DE102010028195A1 (en) | 2010-04-26 | 2011-10-27 | Evonik Rohmax Additives Gmbh | Lubricant for transmissions |
| KR102287600B1 (en) | 2016-05-13 | 2021-08-11 | 에보니크 오퍼레이션즈 게엠베하 | Graft copolymers based on polyolefin backbone and methacrylate side chains |
| FR3072685B1 (en) | 2017-10-20 | 2020-11-06 | Total Marketing Services | COMPOSITION FOR COOLING AND LUBRICATING A MOTORIZATION SYSTEM OF A VEHICLE |
| US11685874B2 (en) | 2019-12-16 | 2023-06-27 | Infineum International Limited | High viscosity index comb polymer viscosity modifiers and methods of modifying lubricant viscosity using same |
| US11384311B2 (en) | 2019-12-16 | 2022-07-12 | Infineum International Limited | High viscosity index comb polymer viscosity modifiers and methods of modifying lubricant viscosity using same |
| US11365273B2 (en) | 2019-12-16 | 2022-06-21 | Infineum International Limited | High viscosity index comb polymer viscosity modifiers and methods of modifying lubricant viscosity using same |
| EP4509584A1 (en) | 2023-07-20 | 2025-02-19 | Infineum International Limited | Flat oil viscosity lubricant compositions |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB618691A (en) * | 1946-10-02 | 1949-02-25 | Standard Oil Dev Co | Improvements in or relating to acrylate ester polymers |
| FR1302679A (en) * | 1961-08-22 | 1962-08-31 | Basf Ag | Product to improve the properties of lubricants |
| US3252949A (en) * | 1960-12-30 | 1966-05-24 | Monsanto Co | Syndiotactic oil-soluble methacrylate polymers |
| NL127451C (en) * | 1962-11-13 | |||
| GB1172697A (en) * | 1966-10-21 | 1969-12-03 | Drayton Res Ltd | Oil Soluble Graft Copolymers. |
| US3417021A (en) * | 1966-12-30 | 1968-12-17 | Exxon Research Engineering Co | Mineral lubricating oil containing a polyester pour depressant |
| GB1163807A (en) * | 1967-08-30 | 1969-09-10 | Shell Int Research | Polyalkyl Methacrylates suitable as Luboil Additives |
| FR1602160A (en) * | 1968-12-23 | 1970-10-19 | Hydraulic and lubricating fluids having - improved flow and shear preps | |
| JPS5148153B2 (en) * | 1972-09-30 | 1976-12-18 | ||
| US4146492A (en) * | 1976-04-02 | 1979-03-27 | Texaco Inc. | Lubricant compositions which exhibit low degree of haze and methods of preparing same |
| DE3544061A1 (en) * | 1985-12-13 | 1987-06-19 | Roehm Gmbh | HIGHLY STABLE MULTI-RANGE LUBRICANTS WITH IMPROVED VISCOSITY INDEX |
| EP0329756B1 (en) * | 1987-08-19 | 1994-05-11 | Pennzoil Products Company | Methacrylate pour point depressants and compositions |
| US5112509A (en) * | 1988-12-22 | 1992-05-12 | Texaco, Inc. | Non-dispersant, shear-stabilizing, and wear-inhibiting viscosity index improver |
-
1993
- 1993-02-04 FR FR9301229A patent/FR2701036B1/en not_active Expired - Fee Related
-
1994
- 1994-02-03 MX MX9400882A patent/MX9400882A/en not_active IP Right Cessation
- 1994-02-04 AU AU61712/94A patent/AU672290B2/en not_active Ceased
- 1994-02-04 WO PCT/US1994/001322 patent/WO1994018288A1/en active IP Right Grant
- 1994-02-04 EP EP94908725A patent/EP0637332B1/en not_active Expired - Lifetime
- 1994-02-04 CA CA002117497A patent/CA2117497A1/en not_active Abandoned
- 1994-02-04 DE DE69432580T patent/DE69432580T2/en not_active Expired - Fee Related
- 1994-02-04 JP JP6518267A patent/JPH07509023A/en not_active Ceased
- 1994-02-04 BR BR9403779A patent/BR9403779A/en not_active Application Discontinuation
- 1994-08-05 KR KR1019940702704A patent/KR950700392A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| DE69432580T2 (en) | 2004-04-08 |
| FR2701036A1 (en) | 1994-08-05 |
| BR9403779A (en) | 1999-06-15 |
| AU672290B2 (en) | 1996-09-26 |
| MX9400882A (en) | 1994-08-31 |
| EP0637332A1 (en) | 1995-02-08 |
| DE69432580D1 (en) | 2003-06-05 |
| KR950700392A (en) | 1995-01-16 |
| JPH07509023A (en) | 1995-10-05 |
| AU6171294A (en) | 1994-08-29 |
| FR2701036B1 (en) | 1995-04-21 |
| WO1994018288A1 (en) | 1994-08-18 |
| EP0637332B1 (en) | 2003-05-02 |
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