CA2185727A1 - Method for testing soot-related viscosity increase - Google Patents
Method for testing soot-related viscosity increaseInfo
- Publication number
- CA2185727A1 CA2185727A1 CA002185727A CA2185727A CA2185727A1 CA 2185727 A1 CA2185727 A1 CA 2185727A1 CA 002185727 A CA002185727 A CA 002185727A CA 2185727 A CA2185727 A CA 2185727A CA 2185727 A1 CA2185727 A1 CA 2185727A1
- Authority
- CA
- Canada
- Prior art keywords
- sample
- carbon black
- viscosity
- paste
- test
- 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
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/26—Oils; viscous liquids; paints; inks
- G01N33/28—Oils, i.e. hydrocarbon liquids
- G01N33/2888—Lubricating oil characteristics, e.g. deterioration
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
- F01M11/00—Component parts, details or accessories, not provided for in, or of interest apart from, groups F01M1/00 - F01M9/00
- F01M11/10—Indicating devices; Other safety devices
- F01M2011/14—Indicating devices; Other safety devices for indicating the necessity to change the oil
- F01M2011/1466—Indicating devices; Other safety devices for indicating the necessity to change the oil by considering quantity of soot
Abstract
A method for testing a sample for soot-related viscosity increase comprising: (a) preparing the sample which comprises a major amount of an oil of lubricating viscosity, (b) measuring the viscosity of the sample (c) preparing a stable sample/paste dispersion of the sample and a carbon black paste, (d) equilibrating the sample/paste dispersion, and (e) measuring the viscosity of the sample/paste dispersion, and a method for predicting physical effects of soot-loading of a sample in a test which measures viscosity increase comprising:
(1) measuring viscosity increase for a series of reference fluids in the test, (2) measuring viscosity increase for the series of reference fluids in a method having steps (a) to (e), (3) developing a curve, (4) evaluating the sample using the method having steps (a) to (e), and (5) interpolating a viscometric effect for the sample using the curve.
(1) measuring viscosity increase for a series of reference fluids in the test, (2) measuring viscosity increase for the series of reference fluids in a method having steps (a) to (e), (3) developing a curve, (4) evaluating the sample using the method having steps (a) to (e), and (5) interpolating a viscometric effect for the sample using the curve.
Description
WO 95130149 2 1 8 S ~ ~ 7 I
METHOD FOR TESTING SOOT-RELATED VISCOSITY INCREASE
FIELD OF THE INVENTION
This inYention relates to a method for testing soot-reiated viscosity increase. More particularly, this invention relates to a method for evaluating the ability of a samp~e or the w",,ua,dLh~ abiiity of samples to cu,,,i,e,, for soot-related viscosity increase. This invention also relates to a method for predicting the physical effect of soot-loading on a sample tested in ald, Iddl di~ed engine tests.
BACKGROUND OF THE INVENTION
Soot formation can be a problem in diesel engines since the engin~
~"~;~u.."lel ,~ promotes soot fommation, 'rrl Im' ~ n~ and dy~lUII lel dL;UI1.
The degree of soot formation depends on design and operaUng i'~al dlll- tu. ~. Problems result in the engine when the soot particles, which are formed in the combustion chamber, and any adsorbed species aggregate to form larger particles which increas~ system ~ ti~:
E~,- " '1~, an engine oil may become so viscous that it cannot be pumped, resulting in engine failure. In addition, hardware design changes have been made in diesel engines to meet emissions requirements and improve en~i,u"",e"~al pélr.l""a,~cé. These changes have resulted in more soot being diverted to the ,, dl li~,d~e and, therefore, certain newer engines have eAi~erie,~ced u,~ viscosity inuease.
Therefore, improved lubricants which perform well in a variety of engine types and varying engine conditions and which have better soot handling , ' "" are needed. Accordingly, ~i~.,/el~ lllell~ of a desired lubricant may require extensive engine tests to determine success.
However, the tests used to evaluate how a given lubricant perfomms, e.g., tests which eYa~uate soot-related viscosity inuease in diesel engines, are very expensiYe. time consuming, and require a large amount of test sample. In addition. testing may be hindered by test stand ~ y.
Dct~.lllil ,i"~ cnucial pdldll._t~.~ for lubricant fommulations by matrixing designed e,~i~élilllèll~. therefore, may be i~lullibili~c.
WO 95/30149 ~ P~
As a result, there has been a clear need in the industry for a bench test which correlates well with ald, Iddl ~ d engine tests, for example, the Mack Truck Technical Services Standard Test Procedure No. 5GT 57 entitled "Mack T-7: Diesel Engine Oil Viscosity EYaluation," dated August 31, 1984 ("Mack T-7") and the Mack Truck Technical Services Standard Test Procedure entitled "Mack T-8: Diesei Engine Oil Viscosity Evaluation," dated October 1 g93 ("Mack T-8"). Several bench test designs have attempted to create simulated soot loading, but published tests have not achieved stable simulated soot loading or S~lrC~SS~
cu"~Idlidn with ald, l~dl di~d engine tests and, at the same time, reproducibility.
One test entailed diluting a used oil and observing the resulting viscosity. The presumption was that a good oil will result in a lower overall viscosity. However, this technique was uns~rre~ l because of the strong non ~..t~" lidl~ nature of thickened oils. For example, addition of a fresh oil to a used oil can produce as much as a 20% viscosity decrease which masks any generated viscosity i"' d~.liUn when different fresh oils are tested and also indicates that oil additions just prior to any viscosity measurement will drastically alter results.
Because it was, t:~yl li~d that soot played a role in the ~I ,i~t:"i"y of engine oils. bench test development using carbon black was initiated.
In one bench test, carbon black was dispersed into fresh engine oils using sonic shear and the viscosity response was measured. This techniqùe was first tested using an ultrasonic bath and then a high power sonicator, e.g., SONICATOR W-375. However, the carbon black in the d;~ aiul ,s would gradually ~ ildll: when left standing in contrast to used oil samples which have the ability to maintain their soot loading in suspension. This method of ueating a carbon di~ aiùn by sonic shear does not sufficiently mimic an engine environment.
Direct dispersion, which is another bench test attempt, requires Iaill~ carbon black directly into a sample. For example, in Chevron's soot-thickening test method LPTL 2007A, a specified amount of carbon black can be blended into an oii and the time for a volume of the oil to-flow through a calibrated glass capillary v;.,r,~""~le( is measured. In another 218S72~
WO 95/30149 r~
bench test method, carbon black has been directly dispersed into a sample using a high-speed blender fo~lowed by agitation at elevated temperatures. "Fluffy" or low density carbon black was used, although it is awkward to handie, because the fluffy carbon black can be dispersed directly by the high-speed blender. However, these methods appear to be ur75~ e55fl1I because the direct di~JelaiulI systems rapidly ~,eui,ciLdlèd.
Consequently, these systems do not accurately simulate soot loading and, therefore, fail to accurately recreate an engine test ell~;.u"",e"~.
This invention seeks to provide a solution to the céii.,ie,~cies in previous bench test systems by providing a bench test that simulates the physical effects of soot-loading in SLdl l~idl ii~èd engine tests and generates results which are reproducible and correlate well with the engine tests. In particular, the bench test method of this invention creates a cdrbon black duylulllèl. '~, size which is an order of magnitude smaller than in the previous bench tests using direct ii~el aiul la and which is more closely related to the size of soot particles in used oils.
SUMMARY OF THE INVENTION
This invention relates to a method for testing a sample for soet-related viscosity increase. The method cc"",u,iaes. (a) preparing the sample which comprises a major amount of an oil of lubricating viscosity, (b) measuring the viscosity of the sample ~c) preparing a stable adlllp~,udaIè dispersion of the sample and a carbon black paste. (d) equilibrating the Sdl~l,u~ daLe ik.~Jelaiùl~, and (e) measuring the viscosity of the sample/paste cii;,,. el aiOI 1.
The stable sd~ dalè ik.~Jel aiul l can be prepared by (i) mixing a high structure, fluffy carbon black with an oii-soluble carrier, which can include 150 solvent neutral base oil or the bulk solvent used in the sample, to form a carbon black mixture, (ii) milling the carbon black mixture to fomm a carbon black paste, and (iii) cul llL,i"i, ly the carbon blackpaste with the sample, which can be selected from the group consisting of ,.ks and fommulated oils, by blending. The blending can be conducted in a Waring blender at about 12,000 to 13,000 rpm for about 1 to 5 minutês. The samplelpaste ui~elaiùl) can then be equilibrated by wo 9~/30149 stirring, which can be conducted on a stirrer for about 5 minut~s to 1 hour at a temperature of 60 to 90C. The sample/paste dispersion can conveniently contain from about 1 to 4 weight % of carbon black.
In another e"lbodi,"e"~, a ~ispe,ad"l can be added, before step (ii), to the carbon black mixture which can then be stirred. In addition, shear can be applied after preparing the sample, afler measuring the viscosity of the sample. aRer preparing the sd~ c~,ld~la d ;.,~el a;ul " or after e~il "' dlil ,~ the sample/paste dispersion in order to mimic the shear effeds of an engine environment.
A further ~" Ibooi, "t" ll of this invention relates to a method for predicting physical effects of soot-loading on a sample in a test which measures viscosity increase. The method ~,uln~ulisea~ (1) measuring viscosity increase for a series of reference fluids in the test, (2) measuring viscosity increase for the series of reference fluids in a method having steps (a) to (e) as described above, (3) i~ ,ui~ ~y a curve, (4) evaluating the sample using the method having steps (a) to (e), and (5) il l`L(L ,UUld~ a v;iw, "t:~, i,, effed for the sample using the curve. The tastmeasuring viscosity increase for which physical effecds of soot loading are being predided can include the Mack T~ test. Co" -~. Iiel l 'y, the sample and the series of reference fluids can differ by on~y one culll~Jul ,~. d or a CulI1~;1Id~ of ~,u,"~ "~, ISa.
DETAILED DESCRIPTION OF THE INVENTiON
In the method for testing a sample for soot-related viscosity, the sample which comprises a major amount of an oil of lubricating viscosity is prepared and then the viscosity of the sample is measured. Generally, viscosity measurements of the sample are made according to standard practices using any conventional v;swllle~e~ including a reverse flow v;~ "~ler. Suitable v.~culll_t~,.a include a Sil v;~uullle~er~ Cannon-Fenske Routine V;~COIll~ela, Cannon-Fenske Opaque v;~co",~e,a, and a Zeiffuchs #4 reverse flow viscometer. The sample which comprises a ~ - major amount of oil of lubricating viscosity can include, for example, 2l857 ~WO95/30149 2 7 mineral oils, synthetic oils, and fully formulated oils which contain, for example, d;;~ue~ Sal lla, ânti-oxidants, and delel yel l~a.
Then a stable sample/paste dispersion is prepared from the samp~e and a carbon black paste. The temm stable refers to the fact that the carbon black particles do not p, eci~ d~e out of the samplelpaste dispersion over a period of time, typically greater than 4 hours, preferably 24 hours to one week. The adll~ dalè dialJelbiOI~ is created to mimic the soot-induced Y;~,~,ul, lell i-, effect of running the sample in an engine test. Typically, 25 to 25û grams of sample are used to prepare the Odlll~ Jaale di~JelaiOI~, preferably 25 to 40 grams.
The carbon b~ack paste is prepared by mixing a carbon b~ack with an oil-so~ub~e carrier to form a carbon blacklcarrier mixture ~lelei"d~lè, carbon black mixture ) and then comminuting the mixture to fomm a finely dispersed carbon b~ack paste (hereafler carbon b~ack paste ) with a carbon black asylu,,,eldle size of less than about 500 nm, preferably 15 nm to 5ûO nm, more preferably 15 nm to 20û nm.
Carbon black having a particie size similar to the particle size of soot can be used, e.g., a particle size ranging from about 10 to 80 nm, preferably 20 to 40 nm. Generally, the carbon black can have any strudure, i.e.. Iow or high structure. Structure is a property wh~ch describes the degree to which the carbon b~ack partic~es have formed àyy~u",è,dLea. Therefore, high stnucture carbon blacks contain ~arger d~stributions of dyylulllel of carbon black partic~es than low structure carbon black. Oi~ dbbUl,lJ~iUII (d~butyl phtha~ate) (ASTM #D-2414-70), which is a measure of the amount of fluid to fill the voids between the partic~es, can be used as a guide to stnucture level. High stnucture carbon black generally has an oil dbbCIl fJ~iUI I value above 100 cc~100 grams, typical~y 100 to 330 cc~1 ûO grams, and ~ow stnucture carbon b~ack genera~y has an oil dùsu",liu,~ value of be~ow 70 cc1100 grams, typically 50 to 70 cc1100 grams. General~y, the higher the oi~ dbbUI ~J~iUI 1, the h~gher the stnucture. The carbon b~ack used to prepare the carbon black paste preferably is high structure since it more close~y mimics the actual soot particle distribution in an engine and, thus, more closely reproduces the typical behavior of an engine envirûnment where relative~y small mass W0 9~iJ30149 fractions of soot, e.g., less than 5%, can cause very large viscosity increases, e.g., greater than 50%. The carbon black can be low density carbon black (referred to as "fluffy" carbon black) or high density, i.e., pelleted. carbon black.
Suitable carbon blacks include carbon black made by Cabot Corporation, Boston, Massachusetts, and listed in Cabot's Technical Report S-36. Exampies of suitable carbon black includes carbon black having the following ASTM D1765 Cl ~ rj, _1;.).) numbers which are ~"""~ y available from Cabot under the trade names shown ,~dl~ iCa"y: N110 (Vulcan~!9 9), N 219 (Rega~@) 600), N326 (Regal~) 300), N472 (\/ulcan E9 XC-72 and its fluffy counterpart Vulcan~ XC-72R), N539 (STERLINGO S0-1), N550 (STERLING@) S0), N762 (STERLING~
NS-1), and N774 (STERLING~ NS).
Preferably, the carbon b~ack is fluffy carbon black, most preferably, a high structure fluffy carbon black, since fluffy carbon black is easier to disperse. If a fluffy carbon black is used, the carbon black can initially be mixed with the oil-soluble carrier with a spatula for about 5 to 30 minutes, preferably 20 to 30 minutes, at a temperature ranging from about 25 to 9û, preferably 25-35 C.
Any oil-soluble carrier which is soluble in the test sample can be used alone or as mixtures. Suitable oil-soluble carriers include solYent neutral base oils having a so~vent neutral number less than 300, preferably 90 to 150, and any bulk solvent used in the test sample. The oil-soluble carrier may cause a small viscosity decrease in the final viscosity measurement but this decrease is offset by the larger viscosity increase -~,o~,i..~. ;i with the presence of carbon black. The oil-soluble carrier viscosity effect can be monitored by first diluting a test sample with 150 solvent neutral base oil according to the quantity to be contained in the carbon black mixture and calculating the tru~ viscosity increase.
However, testing has shown that the extra oil-soluble carrier generally causes an almost constant offset. Therefore, viscosity increases reported herein will neglect the dilution effect.
WO95/30149 21 8~ 72 Z 7 The carrier can be used in an amount which provides good iia,udl :-d~ lUy for the carbon black yet avoids changing ~he ul Idl dUIel iali~.a of the sampie. A suitable ratio of carbon black to oil-soluble carrier can range from 1 99 to 50:50, preferably 5:95 to 30:70, more preferably 10:90 to 20:80.
Optionally, after forming the carbon black mixture, a ui;,uel ~dl 11 or mixtures of ~ia~Jel adl ,~ may be added and stirred to further disperse the carbon black. Suitable dial~e, ad, lla may be selected from any of the well known oil soluble salts, amides, imides, amino-esters, and, " ,es of long chain h~ UCd, uu" 51 Ih5ti~' ItPd mono and d iCdl ~ ylic acids or their anhydrides; ll ,i~w, I.u,~ylate derivatives of long chain hy~il Ul dl b~tla, long chain aliphatic hyd, Ul,dl bUI~S have a polyamine attached directly thereto;
and Mannich ~C"1 ie,)sd~iu" products fonmed by cu"~ier,~i"y a long chain 5~ Ihctit~ 1' ' phenol with ru""dl~iel ,yde and polyalkylene polyamine.
Any dispersion equipment which suf~iciently breaks down the dyylullleld~e size of the carbon black and which sufficiently disperses the carbon black dyylu",e,dies can be used to form the carbon black paste.
Suitable ~ ,uel~iu" equipment depends in part on the type of carbon black selected and can include those described in "Dispersion of Carbon Black For Plastics, Inks, Coatings and Other Special ~ s," Cabot Technical Repott S-31. May 1980, pages 6-15. For example, for fluffy carbon black, three roll mills or colloid mills can be used.
When using a high structure, fluffy carbon black, the carbon black paste is w, .~,_. Iiel ,~ly formed by milling with a three-roll mill which consists of three rolls rotating at different speeds for transfer of material from roll to roll. Material to be dispersed is fed into the nip between the feed and center rolls and the mill base is dragged into the space between these rollers, where patt of the material is retumed to the feed bank and the other part undergoes high shear as it passes through the feed nip and into the space between the center roll and the apron roll. As the material passes through this space, high shear is again achieved and, as the material emerges, it is again split with part returning to the feed bank and the other part flowing to the take-off apron. The mill rollers are adjusted fairly tightly, e.g., dyUlU,~illldlely 400 pâi, tO affo~d a small partic~e size . _ _ _ _ _ _ _ . _ _ _, . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ w0 9s/30149 5~ 8 -result and afford shear to further ~isperso the carbon black.
Ap~l UA;I l ldlely 50 grams of carbon black paste at a time are fed onto the rotating roilers. As described above, the carbon black paste is ll dl larel led from roller to roller thus dispersing the particles and evacuating air from the mixture. A tray with a knife edge can be affixed to the third roller to remove the miiled carbon black paste. At this tight roller tolerance setting, it takes dp~l UA;I I IdLl~!ly 8 to 10 hours to pass about 1600 grams of carbon black paste through the mill. The three roll mill works well in dispersing fluffy carbon black in systems of high or "paste" cul~a;sLel~uy.
A standard draw plate grind gauge can be used to determine the initial seed pattem of the carbon black, the scratches, euleael ,li"y the larger ay~u,lullleldLe sizes measured on the draw plate. The initial seed pattern depends on the carbon black selected. Maximum a~lù"lél a~
sizes falling in the range of 5 to 25 ,um, preferably 5 to 10 ,um, are preferred. Each pass through the three-roll mill Jeu~ases the maximum 6~1ul~1e-dlè size, e.g., ~,u~u,~ 5 IJm afler one pass and d~,UlUA;llldLely 3 ,um aftertwo passeâ, with a maximum aÇJyl~,,l~,.,~ siz~
after milling of typically between 1 and 6 l~m, preferably 1 to 5 pm.
If a pelleted carbon black is used, the pelleted carbon black can be comminuted using high shear d;~ l a;un equipment. Suitable high shear di~ el~iull equipment includes a Banbury mil~, ball mill, shot mill, or pebble mill. Afler comminution, the pelleted carbon black can be combined with an oil-solublQ carrier as described above to form a carbon black mixture. Then the carbon black mixture can be dispersed in the ~ !i;.uer~iul I equipment which suffciently breaks down the aS~5~lul, lel dtè size of the carbon black and which sufficiently disperses the carbon black dyylu",e, dLes as described above. If the pelleted carbon black is combined with the oil-soluble carrier prior to comminution in the high shear di~uél aiOI, equipment, 51 ~hseql l~nt addition of oil-soluble carrier may not be required if the mixture is already paste-like.
Notably, the presumed quality of the sample plays an important role in delé""i"i"g how many "passes" through the ~i;.pél aiul l equipment is required to form the carbon black paste for the bench test. For example, if the sample is thought to have good (e~iahl n,~ to soot-related viscosity : _ , ~ WO95130149 21 ~ 7~
g .
increase (whether as a basestock or a finished formulation) the viscosity increase is expected to be low and, therefore, on~y one pass may be desired to form the caroon black paste. If, however, the sample is thought to be a poorer quality oil, two or three passes may be required for the carbon black mixture in order to more vigorously break down the carbon black a~ulu,,,e, ~ and more thoroughly disperse the carbon black.
After the car~on black paste is prepared. the stable sample/paste dispersion is prepared by blending the carbon black paste into the sample. The blending can be performed by any suitab~e method sufficient to cause mixing and further di~e,aiu,, of the carbon black, e.g., using a Waring blender. The choice of biending equipment may determine the amount of sample required. The blending is conducted at a range from about 8,ûû0 rpm to 18,000 rpm, preferably 12,000 to 13,000 rpm and for a period of time ranging from about 1 to 10 minutes, preferably 1 to 5 minutes, most preferably 3 to 5 minutes. After blending, the Sdlll~ l~JpdalC
dispersion is Pr~ d by stirring on a stirrer for a period of time suflcient to produce a stable sd",,u.~ alc ~ Jclaiul~ and enhance the âOlid-liquid Cullld~.lill~, Culll..licll~ly ranging from 5 minutes to 8 hours, preferably 5 minutes to 1 hour, at a lc,,,pec, ~e of at least 25-C, preferably 25C to 90C, most preferably 60 to 90C.
Generally, the amount of carbon black dispersed in the sample is less than 10 weight % based on the weight of the sample, preferably 0.005 to 10 weight %. and most preferab~y 1 to 4 weight %.
Because an engine er;v;, u"" ,c, ,~ creates a shear effect, for example, by breaking apart viscosity modifiers v~hich may be present in the samp~e, optionally, shear can be applied during the bench test using external l,,c..l 121 liCdl means to mimic shear eflect. Sre~ific~'ly, shear equipment which wou~d have energy ~eve~s sufficient to break po~ymer chains of viscosity modiflers can be used. The required energy level depends on the viscosity modifler present in the sample. The shear can be applied sonically, for examp~e, using a SONICATOR W-375.
Alternatively, a Kurt Orbahn device may be used to shear the sample by high velocity flow through a fixed orifice, which may be tuned for the particu~ar viscosity modifler present in the sample. The shear r~
METHOD FOR TESTING SOOT-RELATED VISCOSITY INCREASE
FIELD OF THE INVENTION
This inYention relates to a method for testing soot-reiated viscosity increase. More particularly, this invention relates to a method for evaluating the ability of a samp~e or the w",,ua,dLh~ abiiity of samples to cu,,,i,e,, for soot-related viscosity increase. This invention also relates to a method for predicting the physical effect of soot-loading on a sample tested in ald, Iddl di~ed engine tests.
BACKGROUND OF THE INVENTION
Soot formation can be a problem in diesel engines since the engin~
~"~;~u.."lel ,~ promotes soot fommation, 'rrl Im' ~ n~ and dy~lUII lel dL;UI1.
The degree of soot formation depends on design and operaUng i'~al dlll- tu. ~. Problems result in the engine when the soot particles, which are formed in the combustion chamber, and any adsorbed species aggregate to form larger particles which increas~ system ~ ti~:
E~,- " '1~, an engine oil may become so viscous that it cannot be pumped, resulting in engine failure. In addition, hardware design changes have been made in diesel engines to meet emissions requirements and improve en~i,u"",e"~al pélr.l""a,~cé. These changes have resulted in more soot being diverted to the ,, dl li~,d~e and, therefore, certain newer engines have eAi~erie,~ced u,~ viscosity inuease.
Therefore, improved lubricants which perform well in a variety of engine types and varying engine conditions and which have better soot handling , ' "" are needed. Accordingly, ~i~.,/el~ lllell~ of a desired lubricant may require extensive engine tests to determine success.
However, the tests used to evaluate how a given lubricant perfomms, e.g., tests which eYa~uate soot-related viscosity inuease in diesel engines, are very expensiYe. time consuming, and require a large amount of test sample. In addition. testing may be hindered by test stand ~ y.
Dct~.lllil ,i"~ cnucial pdldll._t~.~ for lubricant fommulations by matrixing designed e,~i~élilllèll~. therefore, may be i~lullibili~c.
WO 95/30149 ~ P~
As a result, there has been a clear need in the industry for a bench test which correlates well with ald, Iddl ~ d engine tests, for example, the Mack Truck Technical Services Standard Test Procedure No. 5GT 57 entitled "Mack T-7: Diesel Engine Oil Viscosity EYaluation," dated August 31, 1984 ("Mack T-7") and the Mack Truck Technical Services Standard Test Procedure entitled "Mack T-8: Diesei Engine Oil Viscosity Evaluation," dated October 1 g93 ("Mack T-8"). Several bench test designs have attempted to create simulated soot loading, but published tests have not achieved stable simulated soot loading or S~lrC~SS~
cu"~Idlidn with ald, l~dl di~d engine tests and, at the same time, reproducibility.
One test entailed diluting a used oil and observing the resulting viscosity. The presumption was that a good oil will result in a lower overall viscosity. However, this technique was uns~rre~ l because of the strong non ~..t~" lidl~ nature of thickened oils. For example, addition of a fresh oil to a used oil can produce as much as a 20% viscosity decrease which masks any generated viscosity i"' d~.liUn when different fresh oils are tested and also indicates that oil additions just prior to any viscosity measurement will drastically alter results.
Because it was, t:~yl li~d that soot played a role in the ~I ,i~t:"i"y of engine oils. bench test development using carbon black was initiated.
In one bench test, carbon black was dispersed into fresh engine oils using sonic shear and the viscosity response was measured. This techniqùe was first tested using an ultrasonic bath and then a high power sonicator, e.g., SONICATOR W-375. However, the carbon black in the d;~ aiul ,s would gradually ~ ildll: when left standing in contrast to used oil samples which have the ability to maintain their soot loading in suspension. This method of ueating a carbon di~ aiùn by sonic shear does not sufficiently mimic an engine environment.
Direct dispersion, which is another bench test attempt, requires Iaill~ carbon black directly into a sample. For example, in Chevron's soot-thickening test method LPTL 2007A, a specified amount of carbon black can be blended into an oii and the time for a volume of the oil to-flow through a calibrated glass capillary v;.,r,~""~le( is measured. In another 218S72~
WO 95/30149 r~
bench test method, carbon black has been directly dispersed into a sample using a high-speed blender fo~lowed by agitation at elevated temperatures. "Fluffy" or low density carbon black was used, although it is awkward to handie, because the fluffy carbon black can be dispersed directly by the high-speed blender. However, these methods appear to be ur75~ e55fl1I because the direct di~JelaiulI systems rapidly ~,eui,ciLdlèd.
Consequently, these systems do not accurately simulate soot loading and, therefore, fail to accurately recreate an engine test ell~;.u"",e"~.
This invention seeks to provide a solution to the céii.,ie,~cies in previous bench test systems by providing a bench test that simulates the physical effects of soot-loading in SLdl l~idl ii~èd engine tests and generates results which are reproducible and correlate well with the engine tests. In particular, the bench test method of this invention creates a cdrbon black duylulllèl. '~, size which is an order of magnitude smaller than in the previous bench tests using direct ii~el aiul la and which is more closely related to the size of soot particles in used oils.
SUMMARY OF THE INVENTION
This invention relates to a method for testing a sample for soet-related viscosity increase. The method cc"",u,iaes. (a) preparing the sample which comprises a major amount of an oil of lubricating viscosity, (b) measuring the viscosity of the sample ~c) preparing a stable adlllp~,udaIè dispersion of the sample and a carbon black paste. (d) equilibrating the Sdl~l,u~ daLe ik.~Jelaiùl~, and (e) measuring the viscosity of the sample/paste cii;,,. el aiOI 1.
The stable sd~ dalè ik.~Jel aiul l can be prepared by (i) mixing a high structure, fluffy carbon black with an oii-soluble carrier, which can include 150 solvent neutral base oil or the bulk solvent used in the sample, to form a carbon black mixture, (ii) milling the carbon black mixture to fomm a carbon black paste, and (iii) cul llL,i"i, ly the carbon blackpaste with the sample, which can be selected from the group consisting of ,.ks and fommulated oils, by blending. The blending can be conducted in a Waring blender at about 12,000 to 13,000 rpm for about 1 to 5 minutês. The samplelpaste ui~elaiùl) can then be equilibrated by wo 9~/30149 stirring, which can be conducted on a stirrer for about 5 minut~s to 1 hour at a temperature of 60 to 90C. The sample/paste dispersion can conveniently contain from about 1 to 4 weight % of carbon black.
In another e"lbodi,"e"~, a ~ispe,ad"l can be added, before step (ii), to the carbon black mixture which can then be stirred. In addition, shear can be applied after preparing the sample, afler measuring the viscosity of the sample. aRer preparing the sd~ c~,ld~la d ;.,~el a;ul " or after e~il "' dlil ,~ the sample/paste dispersion in order to mimic the shear effeds of an engine environment.
A further ~" Ibooi, "t" ll of this invention relates to a method for predicting physical effects of soot-loading on a sample in a test which measures viscosity increase. The method ~,uln~ulisea~ (1) measuring viscosity increase for a series of reference fluids in the test, (2) measuring viscosity increase for the series of reference fluids in a method having steps (a) to (e) as described above, (3) i~ ,ui~ ~y a curve, (4) evaluating the sample using the method having steps (a) to (e), and (5) il l`L(L ,UUld~ a v;iw, "t:~, i,, effed for the sample using the curve. The tastmeasuring viscosity increase for which physical effecds of soot loading are being predided can include the Mack T~ test. Co" -~. Iiel l 'y, the sample and the series of reference fluids can differ by on~y one culll~Jul ,~. d or a CulI1~;1Id~ of ~,u,"~ "~, ISa.
DETAILED DESCRIPTION OF THE INVENTiON
In the method for testing a sample for soot-related viscosity, the sample which comprises a major amount of an oil of lubricating viscosity is prepared and then the viscosity of the sample is measured. Generally, viscosity measurements of the sample are made according to standard practices using any conventional v;swllle~e~ including a reverse flow v;~ "~ler. Suitable v.~culll_t~,.a include a Sil v;~uullle~er~ Cannon-Fenske Routine V;~COIll~ela, Cannon-Fenske Opaque v;~co",~e,a, and a Zeiffuchs #4 reverse flow viscometer. The sample which comprises a ~ - major amount of oil of lubricating viscosity can include, for example, 2l857 ~WO95/30149 2 7 mineral oils, synthetic oils, and fully formulated oils which contain, for example, d;;~ue~ Sal lla, ânti-oxidants, and delel yel l~a.
Then a stable sample/paste dispersion is prepared from the samp~e and a carbon black paste. The temm stable refers to the fact that the carbon black particles do not p, eci~ d~e out of the samplelpaste dispersion over a period of time, typically greater than 4 hours, preferably 24 hours to one week. The adll~ dalè dialJelbiOI~ is created to mimic the soot-induced Y;~,~,ul, lell i-, effect of running the sample in an engine test. Typically, 25 to 25û grams of sample are used to prepare the Odlll~ Jaale di~JelaiOI~, preferably 25 to 40 grams.
The carbon b~ack paste is prepared by mixing a carbon b~ack with an oil-so~ub~e carrier to form a carbon blacklcarrier mixture ~lelei"d~lè, carbon black mixture ) and then comminuting the mixture to fomm a finely dispersed carbon b~ack paste (hereafler carbon b~ack paste ) with a carbon black asylu,,,eldle size of less than about 500 nm, preferably 15 nm to 5ûO nm, more preferably 15 nm to 20û nm.
Carbon black having a particie size similar to the particle size of soot can be used, e.g., a particle size ranging from about 10 to 80 nm, preferably 20 to 40 nm. Generally, the carbon black can have any strudure, i.e.. Iow or high structure. Structure is a property wh~ch describes the degree to which the carbon b~ack partic~es have formed àyy~u",è,dLea. Therefore, high stnucture carbon blacks contain ~arger d~stributions of dyylulllel of carbon black partic~es than low structure carbon black. Oi~ dbbUl,lJ~iUII (d~butyl phtha~ate) (ASTM #D-2414-70), which is a measure of the amount of fluid to fill the voids between the partic~es, can be used as a guide to stnucture level. High stnucture carbon black generally has an oil dbbCIl fJ~iUI I value above 100 cc~100 grams, typical~y 100 to 330 cc~1 ûO grams, and ~ow stnucture carbon b~ack genera~y has an oil dùsu",liu,~ value of be~ow 70 cc1100 grams, typically 50 to 70 cc1100 grams. General~y, the higher the oi~ dbbUI ~J~iUI 1, the h~gher the stnucture. The carbon b~ack used to prepare the carbon black paste preferably is high structure since it more close~y mimics the actual soot particle distribution in an engine and, thus, more closely reproduces the typical behavior of an engine envirûnment where relative~y small mass W0 9~iJ30149 fractions of soot, e.g., less than 5%, can cause very large viscosity increases, e.g., greater than 50%. The carbon black can be low density carbon black (referred to as "fluffy" carbon black) or high density, i.e., pelleted. carbon black.
Suitable carbon blacks include carbon black made by Cabot Corporation, Boston, Massachusetts, and listed in Cabot's Technical Report S-36. Exampies of suitable carbon black includes carbon black having the following ASTM D1765 Cl ~ rj, _1;.).) numbers which are ~"""~ y available from Cabot under the trade names shown ,~dl~ iCa"y: N110 (Vulcan~!9 9), N 219 (Rega~@) 600), N326 (Regal~) 300), N472 (\/ulcan E9 XC-72 and its fluffy counterpart Vulcan~ XC-72R), N539 (STERLINGO S0-1), N550 (STERLING@) S0), N762 (STERLING~
NS-1), and N774 (STERLING~ NS).
Preferably, the carbon b~ack is fluffy carbon black, most preferably, a high structure fluffy carbon black, since fluffy carbon black is easier to disperse. If a fluffy carbon black is used, the carbon black can initially be mixed with the oil-soluble carrier with a spatula for about 5 to 30 minutes, preferably 20 to 30 minutes, at a temperature ranging from about 25 to 9û, preferably 25-35 C.
Any oil-soluble carrier which is soluble in the test sample can be used alone or as mixtures. Suitable oil-soluble carriers include solYent neutral base oils having a so~vent neutral number less than 300, preferably 90 to 150, and any bulk solvent used in the test sample. The oil-soluble carrier may cause a small viscosity decrease in the final viscosity measurement but this decrease is offset by the larger viscosity increase -~,o~,i..~. ;i with the presence of carbon black. The oil-soluble carrier viscosity effect can be monitored by first diluting a test sample with 150 solvent neutral base oil according to the quantity to be contained in the carbon black mixture and calculating the tru~ viscosity increase.
However, testing has shown that the extra oil-soluble carrier generally causes an almost constant offset. Therefore, viscosity increases reported herein will neglect the dilution effect.
WO95/30149 21 8~ 72 Z 7 The carrier can be used in an amount which provides good iia,udl :-d~ lUy for the carbon black yet avoids changing ~he ul Idl dUIel iali~.a of the sampie. A suitable ratio of carbon black to oil-soluble carrier can range from 1 99 to 50:50, preferably 5:95 to 30:70, more preferably 10:90 to 20:80.
Optionally, after forming the carbon black mixture, a ui;,uel ~dl 11 or mixtures of ~ia~Jel adl ,~ may be added and stirred to further disperse the carbon black. Suitable dial~e, ad, lla may be selected from any of the well known oil soluble salts, amides, imides, amino-esters, and, " ,es of long chain h~ UCd, uu" 51 Ih5ti~' ItPd mono and d iCdl ~ ylic acids or their anhydrides; ll ,i~w, I.u,~ylate derivatives of long chain hy~il Ul dl b~tla, long chain aliphatic hyd, Ul,dl bUI~S have a polyamine attached directly thereto;
and Mannich ~C"1 ie,)sd~iu" products fonmed by cu"~ier,~i"y a long chain 5~ Ihctit~ 1' ' phenol with ru""dl~iel ,yde and polyalkylene polyamine.
Any dispersion equipment which suf~iciently breaks down the dyylullleld~e size of the carbon black and which sufficiently disperses the carbon black dyylu",e,dies can be used to form the carbon black paste.
Suitable ~ ,uel~iu" equipment depends in part on the type of carbon black selected and can include those described in "Dispersion of Carbon Black For Plastics, Inks, Coatings and Other Special ~ s," Cabot Technical Repott S-31. May 1980, pages 6-15. For example, for fluffy carbon black, three roll mills or colloid mills can be used.
When using a high structure, fluffy carbon black, the carbon black paste is w, .~,_. Iiel ,~ly formed by milling with a three-roll mill which consists of three rolls rotating at different speeds for transfer of material from roll to roll. Material to be dispersed is fed into the nip between the feed and center rolls and the mill base is dragged into the space between these rollers, where patt of the material is retumed to the feed bank and the other part undergoes high shear as it passes through the feed nip and into the space between the center roll and the apron roll. As the material passes through this space, high shear is again achieved and, as the material emerges, it is again split with part returning to the feed bank and the other part flowing to the take-off apron. The mill rollers are adjusted fairly tightly, e.g., dyUlU,~illldlely 400 pâi, tO affo~d a small partic~e size . _ _ _ _ _ _ _ . _ _ _, . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ w0 9s/30149 5~ 8 -result and afford shear to further ~isperso the carbon black.
Ap~l UA;I l ldlely 50 grams of carbon black paste at a time are fed onto the rotating roilers. As described above, the carbon black paste is ll dl larel led from roller to roller thus dispersing the particles and evacuating air from the mixture. A tray with a knife edge can be affixed to the third roller to remove the miiled carbon black paste. At this tight roller tolerance setting, it takes dp~l UA;I I IdLl~!ly 8 to 10 hours to pass about 1600 grams of carbon black paste through the mill. The three roll mill works well in dispersing fluffy carbon black in systems of high or "paste" cul~a;sLel~uy.
A standard draw plate grind gauge can be used to determine the initial seed pattem of the carbon black, the scratches, euleael ,li"y the larger ay~u,lullleldLe sizes measured on the draw plate. The initial seed pattern depends on the carbon black selected. Maximum a~lù"lél a~
sizes falling in the range of 5 to 25 ,um, preferably 5 to 10 ,um, are preferred. Each pass through the three-roll mill Jeu~ases the maximum 6~1ul~1e-dlè size, e.g., ~,u~u,~ 5 IJm afler one pass and d~,UlUA;llldLely 3 ,um aftertwo passeâ, with a maximum aÇJyl~,,l~,.,~ siz~
after milling of typically between 1 and 6 l~m, preferably 1 to 5 pm.
If a pelleted carbon black is used, the pelleted carbon black can be comminuted using high shear d;~ l a;un equipment. Suitable high shear di~ el~iull equipment includes a Banbury mil~, ball mill, shot mill, or pebble mill. Afler comminution, the pelleted carbon black can be combined with an oil-solublQ carrier as described above to form a carbon black mixture. Then the carbon black mixture can be dispersed in the ~ !i;.uer~iul I equipment which suffciently breaks down the aS~5~lul, lel dtè size of the carbon black and which sufficiently disperses the carbon black dyylu",e, dLes as described above. If the pelleted carbon black is combined with the oil-soluble carrier prior to comminution in the high shear di~uél aiOI, equipment, 51 ~hseql l~nt addition of oil-soluble carrier may not be required if the mixture is already paste-like.
Notably, the presumed quality of the sample plays an important role in delé""i"i"g how many "passes" through the ~i;.pél aiul l equipment is required to form the carbon black paste for the bench test. For example, if the sample is thought to have good (e~iahl n,~ to soot-related viscosity : _ , ~ WO95130149 21 ~ 7~
g .
increase (whether as a basestock or a finished formulation) the viscosity increase is expected to be low and, therefore, on~y one pass may be desired to form the caroon black paste. If, however, the sample is thought to be a poorer quality oil, two or three passes may be required for the carbon black mixture in order to more vigorously break down the carbon black a~ulu,,,e, ~ and more thoroughly disperse the carbon black.
After the car~on black paste is prepared. the stable sample/paste dispersion is prepared by blending the carbon black paste into the sample. The blending can be performed by any suitab~e method sufficient to cause mixing and further di~e,aiu,, of the carbon black, e.g., using a Waring blender. The choice of biending equipment may determine the amount of sample required. The blending is conducted at a range from about 8,ûû0 rpm to 18,000 rpm, preferably 12,000 to 13,000 rpm and for a period of time ranging from about 1 to 10 minutes, preferably 1 to 5 minutes, most preferably 3 to 5 minutes. After blending, the Sdlll~ l~JpdalC
dispersion is Pr~ d by stirring on a stirrer for a period of time suflcient to produce a stable sd",,u.~ alc ~ Jclaiul~ and enhance the âOlid-liquid Cullld~.lill~, Culll..licll~ly ranging from 5 minutes to 8 hours, preferably 5 minutes to 1 hour, at a lc,,,pec, ~e of at least 25-C, preferably 25C to 90C, most preferably 60 to 90C.
Generally, the amount of carbon black dispersed in the sample is less than 10 weight % based on the weight of the sample, preferably 0.005 to 10 weight %. and most preferab~y 1 to 4 weight %.
Because an engine er;v;, u"" ,c, ,~ creates a shear effect, for example, by breaking apart viscosity modifiers v~hich may be present in the samp~e, optionally, shear can be applied during the bench test using external l,,c..l 121 liCdl means to mimic shear eflect. Sre~ific~'ly, shear equipment which wou~d have energy ~eve~s sufficient to break po~ymer chains of viscosity modiflers can be used. The required energy level depends on the viscosity modifler present in the sample. The shear can be applied sonically, for examp~e, using a SONICATOR W-375.
Alternatively, a Kurt Orbahn device may be used to shear the sample by high velocity flow through a fixed orifice, which may be tuned for the particu~ar viscosity modifler present in the sample. The shear r~
2~8~ o cdn occur before or immediately after measuring the viscosity of the sample, after preDaring a stable sample/paste di~lJe, aiOI 1, or after equilibrating the stable adlllul~/,oda~ dispersion.
The sample/paste di~ur, aiul I is then Lrd, la~ d to a reverse flow vi~ u, "~l~r and the viscosity of the sample/paste ~;;.u~, a;OI~ is rrleasured.
Typical reverse flow V;3~ul~ 1a include Cannon-Fenske Opaque viawlll_'~,,5 and a Zeitfuchs #4 v;~.u",_'~r. The Zeitfuchs #4 v;;.~ u".~
is preferred. Generally, prior to making the v;~.u",~t, i~ measurement, the temperature of the samplelpaste dispersion is e~ ' ' dt~d for 15 minutes to 1 û0C. The results are generally reported as the difference in viscosity between the dia~el aiùl~ and the initial sample.
The method for predicting the physical effects of soot-loading on a sample in a test which measures viscosity increase ("engine test") comprises, as a first step, measuring viscosity increase for a series of reference fluids in the engine test. Then, the viscosity increase is measured for this senes of reference fluids using the method of this inYention ("bench test") described above. A sLd, Iddl l.~ d curve can than be J~ ,lu~,ed for the series of reference fluids in the engine test and the series of reference fluids in the bench test. The sample to be tested is then nun in the bench test to determine Yiscosity increase. The viscosity increase value is compared to the values d~. " ,i, l~d for the reference fluids run in the bench ~est to determine the ranking of the sample. The relative value can then be i"It~ to predict the v;scu"le:IIi,_ effect in the engine test.
The prediction method can also be used to determine the v;3~ulll~ effectofindividualccl~uu~ lllaora~lllLilldLiul~of ~Ill~uul~ ta. Testing individual cu",uu"r~"l le:a~Jol~ses cdn irlclude testing from among many Cdl IdiJdIt:s for a given type of cu" Iyùr,e, Il, e.g., ~L~:Illlillill~ which bas~aLuch more positively affects viscosity increase.
Samples which difler in regard to only one ~,u~,uù~e~ ,I, either by .,o, Icr 1 I~, dtiUI, or actual molecular structure, may be studied by this bench test method in order to advance ulldr~,aLd"~i"~ of formulation crJlllluùn~llt effects in a yiven engine test. In addition, testing via.,r~"~eL, i~. effect of-a ~,UII~bil~d~iUII of co,,,,uull~llls can be dc.,u",,u,i;,l,ed by testing the utility W095/30149 21 8S 72 7 P~
-- 11 ;
and/or effects of a L.UII IUUI 1~111 c~ass. e.g., ~iaU~l aal IL~, rust inhibitors, or dllliu~id~lllla. by using sets of samples a,ue~iri~a'!y designed to highlight the contribution of each ~u, I ,uu, ,~"l in each set In either case, major effects can be obtained by subtractive blending, e.g., ~.u~ ul)el ILs can be inserted and then ~I;. "i, Icll~d from the test sample to determine the eflect on viscosity response Al~tllldliiciy, several test samples which differ from each other by only one ,u,,,uu, ,t:"~ or a uullluill~Liul) of Cullluul)e~ a can be nun against reference fluid(s) The engine tests can include the Mack T-7 and the Mack T-8 tests, which are part of a panel used to determine ~cr ~, ' ' 'y of oils for engines manufactured by Mack Truck Company. In the Mack T-7 test, a direct injection, in-line six cylinder four stroke turbo-charged series charge air-cooled uulll~ asi~,~ ignition engine is operated at a low speed, high torque, steady state condition. The kinematic viscosity of the lubricant is measured after the engine has nun 1 ûû hours and at the end of the test at 15û hours. These two points are used to determine a rate of viscosity change ("viscosity slope"~. A passing oil will de:lllul ,~l, a viscosity increase less than or equal to û.û4 cStlhr.
The Mack T-8 test is more severe than the Mack T-7 test . The Mack T-8 test takes into account the retarding of fuel injection timing in newer engines to allow the engines to pass emission requirements. The Mack T-8 also requires fuels having a lower sulfur content. The retarded fuel injection results in high soot related viscosity increase, high filter pressure drops, and sludge deposits in these newer engines. The test runs at 1800 rpm for 250 hours. Throughout the test, soot levels and viscosity are measured. The measured V;~c0~ 5 and soot levels are used to i~ ,ulc,l-~ a viscosity at a soot level of 3.8 weight %. An oii passes if that viscosity differs from the lowest viscosity measured in the test by 11.5 cSt or less. If two tests are nun, the average result must be 12.5 cSt or less. If three tests are nun, the average result must be 13.û
cSt or less.
This invention may be further ulnJt:la~uod from the following examples which are not intended to limit the scope of the claims.
5~0149 ~ 2 -EXAMP~ES
1. Correlation With The Mack T-7 Test A. Three fully formulated oils were prepared and run in the Mack T-7 test. These same oils were then run according to the bench test of this invention by first measuring the viscosity of the oils after a~lowing the oils to equilibrate for 15 minutes at 100 C in a Zeiffuchs #4 reverse flow v.~.,u,,,e:ler. Then, a carbon black mixture was obtained by hand mixing Cabot XC-72R carbon black in 150 solvent neutral base oil with a carbon black to base oil weight ratio of 20:80 and milling the carbon black paste in a three-roll mill until a maximum particle size of 2 um was measured on a draw plate, which required three passes through the mill.
2.4 grams of carbon black paste and 37.6 grams of sample were weighed and placed into a Waring mini-cup blending container and blended for five minutes at 13,000 rpm. The mixture was ~ Iafe~ d to a 150 ml beaker and stirred at 70~C for one hour. The sample/paste dispersion was then charged to a Zeitfuchs #4 reverse flow v;;,uu",~l~,r and the viscosity was read after the sample/paste ~;.",t:, aiul I was eq~ for 15 minutes at 100-C.
Below are the results from the Mack T-7 test and the bench test, reported as viscosity increase in units of cSt as measured at 1 00C.
Mack T-7 Test1 Carbon Black2 (cSt) Bench Test (cSt~
SAMPLE
5.69; 5.17 11.19 22.17; 2.07 7.40 31.77 1.68 1 The maximum viscosity increase over the 150 hour engine test.
2The amount of carbon black loading was 1.2%.
WO 95130149 21 8 S 7~ 7 r ~
As shown by the data, the rank order for Yiscosity increase results in the bench test correlates exactly with the Mack T-7 viscosity increase results.
8. SeYen fully formulated oils were prepared and run in the Mack T-7 test. These same oils were then mn according to the bench test of this invention by first measuring the viscosity of the oils after allowing the oils to equilibrate for 15 minutes at 100 C in a Zeiffuchs #4 reYerse flow v;~.,.""~t.,.. Then, a carbon black mixture was obtained by hand mixing Cabot XC-72R carbon black in 150 solYent neutral base oil with a carbon black to base oil weight ratio of 20:80 and milling the carbon black paste in a three-roll mill until a maximum particle size of 2 ,um was measured on a draw plate. which required three passes through the mill.
2.80 grams of carbon black paste and 37.2 grams of sample were weighed and placed into a Waring mini-cup blending container and blended for fiYe minutes at 13,000 rpm. The mixture was 1, dl larel I ed to a 150 ml beaker and stirred at 70C for one hour. The 5dllltJ~,',vcl~Les di..~el ai~n was then charged to a Zeiffuchs #4 reverse flow v;~,~",ele, and the Yiscosity was read after the s~ ale dislJel aiOI) was ~'1' "" , ' ' for 15 minutes at 100-C.
Mack T-73 Carbon Black4 (cSt~ Bench Test (cSt~
SAMPLE
The sample/paste di~ur, aiul I is then Lrd, la~ d to a reverse flow vi~ u, "~l~r and the viscosity of the sample/paste ~;;.u~, a;OI~ is rrleasured.
Typical reverse flow V;3~ul~ 1a include Cannon-Fenske Opaque viawlll_'~,,5 and a Zeitfuchs #4 v;~.u",_'~r. The Zeitfuchs #4 v;;.~ u".~
is preferred. Generally, prior to making the v;~.u",~t, i~ measurement, the temperature of the samplelpaste dispersion is e~ ' ' dt~d for 15 minutes to 1 û0C. The results are generally reported as the difference in viscosity between the dia~el aiùl~ and the initial sample.
The method for predicting the physical effects of soot-loading on a sample in a test which measures viscosity increase ("engine test") comprises, as a first step, measuring viscosity increase for a series of reference fluids in the engine test. Then, the viscosity increase is measured for this senes of reference fluids using the method of this inYention ("bench test") described above. A sLd, Iddl l.~ d curve can than be J~ ,lu~,ed for the series of reference fluids in the engine test and the series of reference fluids in the bench test. The sample to be tested is then nun in the bench test to determine Yiscosity increase. The viscosity increase value is compared to the values d~. " ,i, l~d for the reference fluids run in the bench ~est to determine the ranking of the sample. The relative value can then be i"It~ to predict the v;scu"le:IIi,_ effect in the engine test.
The prediction method can also be used to determine the v;3~ulll~ effectofindividualccl~uu~ lllaora~lllLilldLiul~of ~Ill~uul~ ta. Testing individual cu",uu"r~"l le:a~Jol~ses cdn irlclude testing from among many Cdl IdiJdIt:s for a given type of cu" Iyùr,e, Il, e.g., ~L~:Illlillill~ which bas~aLuch more positively affects viscosity increase.
Samples which difler in regard to only one ~,u~,uù~e~ ,I, either by .,o, Icr 1 I~, dtiUI, or actual molecular structure, may be studied by this bench test method in order to advance ulldr~,aLd"~i"~ of formulation crJlllluùn~llt effects in a yiven engine test. In addition, testing via.,r~"~eL, i~. effect of-a ~,UII~bil~d~iUII of co,,,,uull~llls can be dc.,u",,u,i;,l,ed by testing the utility W095/30149 21 8S 72 7 P~
-- 11 ;
and/or effects of a L.UII IUUI 1~111 c~ass. e.g., ~iaU~l aal IL~, rust inhibitors, or dllliu~id~lllla. by using sets of samples a,ue~iri~a'!y designed to highlight the contribution of each ~u, I ,uu, ,~"l in each set In either case, major effects can be obtained by subtractive blending, e.g., ~.u~ ul)el ILs can be inserted and then ~I;. "i, Icll~d from the test sample to determine the eflect on viscosity response Al~tllldliiciy, several test samples which differ from each other by only one ,u,,,uu, ,t:"~ or a uullluill~Liul) of Cullluul)e~ a can be nun against reference fluid(s) The engine tests can include the Mack T-7 and the Mack T-8 tests, which are part of a panel used to determine ~cr ~, ' ' 'y of oils for engines manufactured by Mack Truck Company. In the Mack T-7 test, a direct injection, in-line six cylinder four stroke turbo-charged series charge air-cooled uulll~ asi~,~ ignition engine is operated at a low speed, high torque, steady state condition. The kinematic viscosity of the lubricant is measured after the engine has nun 1 ûû hours and at the end of the test at 15û hours. These two points are used to determine a rate of viscosity change ("viscosity slope"~. A passing oil will de:lllul ,~l, a viscosity increase less than or equal to û.û4 cStlhr.
The Mack T-8 test is more severe than the Mack T-7 test . The Mack T-8 test takes into account the retarding of fuel injection timing in newer engines to allow the engines to pass emission requirements. The Mack T-8 also requires fuels having a lower sulfur content. The retarded fuel injection results in high soot related viscosity increase, high filter pressure drops, and sludge deposits in these newer engines. The test runs at 1800 rpm for 250 hours. Throughout the test, soot levels and viscosity are measured. The measured V;~c0~ 5 and soot levels are used to i~ ,ulc,l-~ a viscosity at a soot level of 3.8 weight %. An oii passes if that viscosity differs from the lowest viscosity measured in the test by 11.5 cSt or less. If two tests are nun, the average result must be 12.5 cSt or less. If three tests are nun, the average result must be 13.û
cSt or less.
This invention may be further ulnJt:la~uod from the following examples which are not intended to limit the scope of the claims.
5~0149 ~ 2 -EXAMP~ES
1. Correlation With The Mack T-7 Test A. Three fully formulated oils were prepared and run in the Mack T-7 test. These same oils were then run according to the bench test of this invention by first measuring the viscosity of the oils after a~lowing the oils to equilibrate for 15 minutes at 100 C in a Zeiffuchs #4 reverse flow v.~.,u,,,e:ler. Then, a carbon black mixture was obtained by hand mixing Cabot XC-72R carbon black in 150 solvent neutral base oil with a carbon black to base oil weight ratio of 20:80 and milling the carbon black paste in a three-roll mill until a maximum particle size of 2 um was measured on a draw plate, which required three passes through the mill.
2.4 grams of carbon black paste and 37.6 grams of sample were weighed and placed into a Waring mini-cup blending container and blended for five minutes at 13,000 rpm. The mixture was ~ Iafe~ d to a 150 ml beaker and stirred at 70~C for one hour. The sample/paste dispersion was then charged to a Zeitfuchs #4 reverse flow v;;,uu",~l~,r and the viscosity was read after the sample/paste ~;.",t:, aiul I was eq~ for 15 minutes at 100-C.
Below are the results from the Mack T-7 test and the bench test, reported as viscosity increase in units of cSt as measured at 1 00C.
Mack T-7 Test1 Carbon Black2 (cSt) Bench Test (cSt~
SAMPLE
5.69; 5.17 11.19 22.17; 2.07 7.40 31.77 1.68 1 The maximum viscosity increase over the 150 hour engine test.
2The amount of carbon black loading was 1.2%.
WO 95130149 21 8 S 7~ 7 r ~
As shown by the data, the rank order for Yiscosity increase results in the bench test correlates exactly with the Mack T-7 viscosity increase results.
8. SeYen fully formulated oils were prepared and run in the Mack T-7 test. These same oils were then mn according to the bench test of this invention by first measuring the viscosity of the oils after allowing the oils to equilibrate for 15 minutes at 100 C in a Zeiffuchs #4 reYerse flow v;~.,.""~t.,.. Then, a carbon black mixture was obtained by hand mixing Cabot XC-72R carbon black in 150 solYent neutral base oil with a carbon black to base oil weight ratio of 20:80 and milling the carbon black paste in a three-roll mill until a maximum particle size of 2 ,um was measured on a draw plate. which required three passes through the mill.
2.80 grams of carbon black paste and 37.2 grams of sample were weighed and placed into a Waring mini-cup blending container and blended for fiYe minutes at 13,000 rpm. The mixture was 1, dl larel I ed to a 150 ml beaker and stirred at 70C for one hour. The 5dllltJ~,',vcl~Les di..~el ai~n was then charged to a Zeiffuchs #4 reverse flow v;~,~",ele, and the Yiscosity was read after the s~ ale dislJel aiOI) was ~'1' "" , ' ' for 15 minutes at 100-C.
Mack T-73 Carbon Black4 (cSt~ Bench Test (cSt~
SAMPLE
3.72 1 3.66 2 1.91 8.7 3 2.89 9.7 4 1.46 4.8 5 1.27 2.3 6 0.86 2.7 7 0.70 1.9 3Viscosity increase during the last 50 hours of the engine test.
4The amount of carbon black loading was 1.4%
The test results indicate that the bench test d~ i" ,i, I(~Lès between good and bad oils and conrelates with the Mack T-7 test.
2~ 4- 0 Il. Corre~ation With ThQ Mack T-8 Test SeYen fully formulated oils were prepared and run in the Mack T-8 test. These same oils were then run according to the bench test of this invention. Specifically, the viscosity of the oils were measured by a Zeiffuchs #4 reverse flow v;scu" ,_~u., after the oils were eg~ ~ "' d~l~!d for 15 minutes at 100C. A carbon black mixture was obtained by hand-mixing Cabot XC-72R carbon black in 150 solvent neutral base oil with a carbon black to base oil ratio of 20:80, the resulting carbon black paste was further dispersed using a 3-roll mill. The carbon black paste was milled twice giving a maximum particle size of 2.5-3.0 microns.
A~ u,~l,lldLt:ly 3 or 4 grams of the milled carbon black paste and d,U~ lU,~;llldL~Iy 27 or 36 grams of sample, l~a~ _ly, to provide a carbon black active ingredient co"ce"t, dLiul, of 2% by weight, were weighed and placed into a Waring blender and blended for 5 minutes at ~ 3,000 rpm.
This blended mixture was then further e~ll 1 ' ' dL~d by placing it into a 150-ml beaker and stirring at low speed for 1 hour at 70C. The sample containing 2 weight % finely dispersed carbon black was then charged to the Zeitfuchs #4 reverse-flow vk,~,ul.._h~.~, where it was allowed 15 minutes to equilibrate to 1 OO~C, at which point the viscosity of the Sdl I l,JIlS/~Jdabdispersion was taken.
8elow are the results from the Mack T-8 test (reported as viscosity increase at 3.8% soot relative to the lowest measured viscosity during this 250-hr engine test) and the bench test. All viscosity increases are reported in unitâ of cSt as measured at 100 C and represent the viscosity of the Sdl I l,UI~pdal~ dis,U~:I aiOIl ~.UI Ildil 1;l Iy finely dispersed carbon black minus the viscosity of th~ oil.
I~W095/30149 21~ ~7 ~; t' r~.. .
Carbon Black5 Mack T-8 Enaine Test Bench Test Samole 30.0 36.29 230.7 28.82 322.0 1 9.28 41 1 .0 4.07 51 1 .3 3.14 6 7.6 2.91 7 5.2 1.13 51n Sampie Nos. 1, 2, 3. and 4, the amount of carbon black was 4 grams and the amount of sample was 36 srams. In Sample Nos. 5, 6, and 7, the amount of carbon black paste was 3 srams and the amount of sample was 27 grams.
As shown by this data, the rank order of the bench test results correlates well with the Mack T-8 engine test results at 3.ô% soot.
Ill. Individual Component Response Three fully formulated oiis having different t, ~ but the same detersent inhibitor package and viscosity modifier were prepared and run in the Mack T-8. These same oils were then nun according to the bench test of this invention. ~r - ~ ly, the viscosity of the oils were measured by a Zeiffuchs #4 reverse flow Y;SC~ t~,r, after the oils were e~g~ ~i for 15 minutes at 1 00C. A carbon black mixture was obtained by hand-mixing Cabot XC-72R carbon black in 150 solvent neutral base oil with a carbon black to base oil ratio of 20:80, the resulting caroon black paste was further dispersed using a 3-roll mill. The carbon black paste was milled twice giving a maximum particle size of 2.5-3.0 microns. Ap~l u~ dL~ly 3 grams of the milled caroon black paste and I U.~ l 'y 27 grams of sample, respectively, to provide a carbon black active ingredient uu"-,~"~, d~i~n of 2% by weight, were weighed and plac~d WO95/30149 ~ S~ - 16-into a Waring blender and blended for 5 minutes at 13 000 rpm. This b~ended mixture was then further e~ d~ed by placiny it into a 1 50-ml beaker and stirring at low speed for 1 hour at 70C. The sample . u"lai"i"~ 2 weight % finely dispersed carbon black was then charged to the Zeiffuchs #4 reverse-flow v;~cu",_t~l where it was allowed 15 minutes to egl ~ e tû 1 OO~C at which point the viscosity of the sa~ pc,ate dis~Jel aiul I was taken.
Below are the results from the Mack T-8 test (reported as viscosity increase at 3.8% soot relative to the lowest measured viscosity during this 250-hr engine test) and the bench test. All viscosity increases are reported in units of cSt as measured at 1 00C and represent the viscosity of the samplelpaste di~Jel biun cu, llail ,i"g finely dispersed carbon black minus the viscosity of the oil.
Carbon Black Mack T~ Enaine Test Bench Test SamD~e 7.6 2.91 25.2 1.13 34.6 1.05 As shown by this data the rank order of the bench test results correlate exactly with the Mack T-8 engine test results. Therefore the effectiveness of the l~rq~ k~ used which were varied in each sample was d~ . " ,i"ed.
4The amount of carbon black loading was 1.4%
The test results indicate that the bench test d~ i" ,i, I(~Lès between good and bad oils and conrelates with the Mack T-7 test.
2~ 4- 0 Il. Corre~ation With ThQ Mack T-8 Test SeYen fully formulated oils were prepared and run in the Mack T-8 test. These same oils were then run according to the bench test of this invention. Specifically, the viscosity of the oils were measured by a Zeiffuchs #4 reverse flow v;scu" ,_~u., after the oils were eg~ ~ "' d~l~!d for 15 minutes at 100C. A carbon black mixture was obtained by hand-mixing Cabot XC-72R carbon black in 150 solvent neutral base oil with a carbon black to base oil ratio of 20:80, the resulting carbon black paste was further dispersed using a 3-roll mill. The carbon black paste was milled twice giving a maximum particle size of 2.5-3.0 microns.
A~ u,~l,lldLt:ly 3 or 4 grams of the milled carbon black paste and d,U~ lU,~;llldL~Iy 27 or 36 grams of sample, l~a~ _ly, to provide a carbon black active ingredient co"ce"t, dLiul, of 2% by weight, were weighed and placed into a Waring blender and blended for 5 minutes at ~ 3,000 rpm.
This blended mixture was then further e~ll 1 ' ' dL~d by placing it into a 150-ml beaker and stirring at low speed for 1 hour at 70C. The sample containing 2 weight % finely dispersed carbon black was then charged to the Zeitfuchs #4 reverse-flow vk,~,ul.._h~.~, where it was allowed 15 minutes to equilibrate to 1 OO~C, at which point the viscosity of the Sdl I l,JIlS/~Jdabdispersion was taken.
8elow are the results from the Mack T-8 test (reported as viscosity increase at 3.8% soot relative to the lowest measured viscosity during this 250-hr engine test) and the bench test. All viscosity increases are reported in unitâ of cSt as measured at 100 C and represent the viscosity of the Sdl I l,UI~pdal~ dis,U~:I aiOIl ~.UI Ildil 1;l Iy finely dispersed carbon black minus the viscosity of th~ oil.
I~W095/30149 21~ ~7 ~; t' r~.. .
Carbon Black5 Mack T-8 Enaine Test Bench Test Samole 30.0 36.29 230.7 28.82 322.0 1 9.28 41 1 .0 4.07 51 1 .3 3.14 6 7.6 2.91 7 5.2 1.13 51n Sampie Nos. 1, 2, 3. and 4, the amount of carbon black was 4 grams and the amount of sample was 36 srams. In Sample Nos. 5, 6, and 7, the amount of carbon black paste was 3 srams and the amount of sample was 27 grams.
As shown by this data, the rank order of the bench test results correlates well with the Mack T-8 engine test results at 3.ô% soot.
Ill. Individual Component Response Three fully formulated oiis having different t, ~ but the same detersent inhibitor package and viscosity modifier were prepared and run in the Mack T-8. These same oils were then nun according to the bench test of this invention. ~r - ~ ly, the viscosity of the oils were measured by a Zeiffuchs #4 reverse flow Y;SC~ t~,r, after the oils were e~g~ ~i for 15 minutes at 1 00C. A carbon black mixture was obtained by hand-mixing Cabot XC-72R carbon black in 150 solvent neutral base oil with a carbon black to base oil ratio of 20:80, the resulting caroon black paste was further dispersed using a 3-roll mill. The carbon black paste was milled twice giving a maximum particle size of 2.5-3.0 microns. Ap~l u~ dL~ly 3 grams of the milled caroon black paste and I U.~ l 'y 27 grams of sample, respectively, to provide a carbon black active ingredient uu"-,~"~, d~i~n of 2% by weight, were weighed and plac~d WO95/30149 ~ S~ - 16-into a Waring blender and blended for 5 minutes at 13 000 rpm. This b~ended mixture was then further e~ d~ed by placiny it into a 1 50-ml beaker and stirring at low speed for 1 hour at 70C. The sample . u"lai"i"~ 2 weight % finely dispersed carbon black was then charged to the Zeiffuchs #4 reverse-flow v;~cu",_t~l where it was allowed 15 minutes to egl ~ e tû 1 OO~C at which point the viscosity of the sa~ pc,ate dis~Jel aiul I was taken.
Below are the results from the Mack T-8 test (reported as viscosity increase at 3.8% soot relative to the lowest measured viscosity during this 250-hr engine test) and the bench test. All viscosity increases are reported in units of cSt as measured at 1 00C and represent the viscosity of the samplelpaste di~Jel biun cu, llail ,i"g finely dispersed carbon black minus the viscosity of the oil.
Carbon Black Mack T~ Enaine Test Bench Test SamD~e 7.6 2.91 25.2 1.13 34.6 1.05 As shown by this data the rank order of the bench test results correlate exactly with the Mack T-8 engine test results. Therefore the effectiveness of the l~rq~ k~ used which were varied in each sample was d~ . " ,i"ed.
Claims (14)
1. A method for testing a sample for soot-related viscosity increase, the method comprising:
(a) preparing the sample which comprises a major amount of an oil of lubricating viscosity, (b) measuring the viscosity of the sample, (c) preparing a stable sample/paste dispersion of the sample and carbon black paste, (d) equilibrating the sample/paste dispersion, and (e) measuring the viscosity of the sample/paste dispersion.
(a) preparing the sample which comprises a major amount of an oil of lubricating viscosity, (b) measuring the viscosity of the sample, (c) preparing a stable sample/paste dispersion of the sample and carbon black paste, (d) equilibrating the sample/paste dispersion, and (e) measuring the viscosity of the sample/paste dispersion.
2. The method of claim 1, wherein the sample/paste dispersion is prepared by (i) mixing a high structure, fluffy carbon black with an oil-soluble carrier to form a carbon black mixture, (ii) milling the carbon black mixture to form a carbon black paste, and (iii) combining the carbon black paste with the sample by blending.
3. The method of claim 1, wherein the sample/paste dispersion is equilibrated by stirring.
4. The method of claim 2, wherein the blending is conducted in a Waring blender at about 12,000 to 13,000 rpm for about 1 to 5 minutes.
5. The method of claim 3, wherein the stirring is conducted on a stirrer for about 5 minutes to 1 hour at a temperature of 60 to 90°C.
6. The method of claim 2, wherein the oil-soluble carrier is 150 solvent neutral base oil.
7. The method of claim 2, wherein the carrier is the same as a bulk solvent used in the sample.
8. The method of claim 2, wherein the sample/paste dispersion contains from about 1 to 4 weight % of carbon black, based on the weight of the sample.
9. The method of claim 2. wherein before step (ii) a dispersant is added to the carbon black mixture and the carbon black mixture is stirred.
10. The method of claim 1, wherein the sample is selected from the group consisting of basestocks and formulated oils.
11. The method of claim 1, wherein shear is applied after preparing the sample, after measuring the viscosity of the sample, after preparing the sample/paste dispersion, or after equilibrating the sample/paste dispersion.
12. A method for predicting physical effects of soot-loading on a sample in a test which measures viscosity increase, the method comprising:
(1) measuring viscosity increase for a series of reference fluids in the test, (2) measuring viscosity increase for the series of reference fluids using the method of claim 1, (3) developing a curve, (4) evaluating the sample using the method of claim 1, and (5) interpolating a viscometric effect for the sample using the curve.
(1) measuring viscosity increase for a series of reference fluids in the test, (2) measuring viscosity increase for the series of reference fluids using the method of claim 1, (3) developing a curve, (4) evaluating the sample using the method of claim 1, and (5) interpolating a viscometric effect for the sample using the curve.
13. The method of claim 12, wherein the test is Mack T-8.
14. The method of claim 12, wherein the sample and the series of reference fluids differ by one component or a combination of components.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US234,079 | 1994-04-28 | ||
| US08/234,079 US5571950A (en) | 1994-04-28 | 1994-04-28 | Method for testing soot-related viscosity increase |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2185727A1 true CA2185727A1 (en) | 1995-11-09 |
Family
ID=22879821
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002185727A Abandoned CA2185727A1 (en) | 1994-04-28 | 1995-04-27 | Method for testing soot-related viscosity increase |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5571950A (en) |
| EP (1) | EP0757793B1 (en) |
| CA (1) | CA2185727A1 (en) |
| DE (1) | DE69506099T2 (en) |
| WO (1) | WO1995030149A1 (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5817928A (en) * | 1997-04-14 | 1998-10-06 | Csi Technology, Inc. | Method and apparatus for lubrication fluid analysis |
| JP3843381B2 (en) * | 1997-09-05 | 2006-11-08 | 株式会社小松製作所 | Engine lubrication oil replacement time prediction apparatus and prediction method |
| US6023961A (en) | 1998-04-02 | 2000-02-15 | Reliance Electric Industrial Company | Micro-viscosity sensor and lubrication analysis system employing the same |
| US6546785B1 (en) * | 1998-04-02 | 2003-04-15 | Rockwell Automation Technologies, Inc. | System and method for dynamic lubrication adjustment for a lubrication analysis system |
| US7134323B1 (en) | 1998-04-02 | 2006-11-14 | Rockwell Automation Technologies, Inc. | System and method for dynamic lubrication adjustment for a lubrication analysis system |
| US7560420B2 (en) * | 2004-12-23 | 2009-07-14 | Rohmax Additives Gmbh | Oil composition for lubricating an EGR equipped diesel engine and an EGR equipped diesel engine comprising same |
| US9175146B2 (en) * | 2006-08-08 | 2015-11-03 | Sabic Global Technologies B.V. | Thermal conductive polymeric PTC compositions |
| WO2012021620A1 (en) * | 2010-08-10 | 2012-02-16 | Board Of Regents, The University Of Texas System | Processes for synthesizing fluorescent carbon nanoparticles and compositions and uses thereof |
| CN102135507B (en) * | 2010-12-26 | 2013-07-24 | 中国第一汽车集团公司 | Method for testing and simulating dispersion of engine oil |
| US8927469B2 (en) | 2011-08-11 | 2015-01-06 | Afton Chemical Corporation | Lubricant compositions containing a functionalized dispersant |
| CN102967696B (en) * | 2012-11-13 | 2014-10-01 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Method for predicting gas in direct-current-transmission conversion transformation oil |
| CN107615536A (en) * | 2015-06-04 | 2018-01-19 | 日产化学工业株式会社 | Primary coat paper tinsel for energy storage device electrode |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1498764A1 (en) * | 1964-09-28 | 1969-06-12 | Gerin Fernand L | Device for comparing the viscosity of two fluids |
| GB8628523D0 (en) * | 1986-11-28 | 1987-01-07 | Shell Int Research | Lubricating composition |
| US4794787A (en) * | 1987-06-05 | 1989-01-03 | Gordon Myron S | High-low viscosity comparator |
| GB2235695A (en) * | 1989-09-05 | 1991-03-13 | Shell Int Research | Novel additives for lubricating oils |
| DE68909050T2 (en) * | 1989-11-06 | 1994-03-24 | Kyoseki Seihin Gijutsu Kenk | Wear detection device for lubricating oil. |
-
1994
- 1994-04-28 US US08/234,079 patent/US5571950A/en not_active Expired - Fee Related
-
1995
- 1995-04-27 DE DE69506099T patent/DE69506099T2/en not_active Expired - Fee Related
- 1995-04-27 EP EP95918859A patent/EP0757793B1/en not_active Expired - Lifetime
- 1995-04-27 WO PCT/US1995/005200 patent/WO1995030149A1/en active IP Right Grant
- 1995-04-27 CA CA002185727A patent/CA2185727A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| DE69506099D1 (en) | 1998-12-24 |
| WO1995030149A1 (en) | 1995-11-09 |
| EP0757793A1 (en) | 1997-02-12 |
| EP0757793B1 (en) | 1998-11-18 |
| DE69506099T2 (en) | 1999-05-06 |
| US5571950A (en) | 1996-11-05 |
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