US3634249A

US3634249A - Lubricating oil composition

Info

Publication number: US3634249A
Application number: US776012A
Authority: US
Inventors: Robert Dupas; Marcel Ostyn
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1967-11-20
Filing date: 1968-11-15
Publication date: 1972-01-11
Anticipated expiration: 1989-01-11
Also published as: SE343320B; FR1552150A; DE1810085B2; DE1810085A1; NL6816543A; GB1208968A; DE1810085C3

Abstract

LUBRICATING OIL COMPOSITIONS EXHIBITING GOOD VISCOSITY INDEX, POUR POINT, RESISTANCE TO OXIDATION, AND SHEAR STABILITY PROPERTIES MAY BE FORMULATED FROM MINERAL OIL OR SYNTHETIC OIL BASE STOCKS AND OILY ETHYLENE-PROPYLENE COPOYLYMERS BOILING ABOUVE 450* C. PREPARED FROM ETHYLENE AND PROPYLENE IN MOLE RATIO OF 1.5-0.43:1.

Description

Jan. 11, 1972 Filed Nov. 15, 1968 R. DUPAS ET AL LUBRICATING OIL COMPOSITION 2 Sheets-Sheet l wr LUMPULYMEI? 1w, 798. 9C 7378.

20 FIG. 4

/o WT EUMPULYMEI? United States Patent 3,634,249 LUBRICATING OIL COMPOSITION Robert Dupas and Marcel Ostyn, Mont-Saint-Aignan, France, assignors to Esso Research and Engineering Company Filed Nov. 15, 1968, Ser. No. 776,012 Claims priority, application France, Nov. 20, 1967,

Int. or. (from 1/18 US. Cl. 252-59 7 Claims ABSTRACT OF THE DISCLOSURE Lubricating oil compositions exhibiting good viscosity index, pour point, resistance to oxidation, and shear stability properties may be formulated from mineral oil or synthetic oil base stocks and oily ethylene-propylene copolymers boiling above 450 C. prepared from ethylene and propylene in mole ratio of 1.5-0.4321.

The present invention relates to compositions of oily ethylene/propylene copolymers and mineral and/or synthetic oils of the ester type. These compositions have good properties as regards viscosity, in particular viscosity index, pour point, stability in respect of shearing, oxidation, heat etc. It is possible to obtain multi-grade oils rising to grade SAE IO-W-SO.

It is well known that to obtain multi-grade lubricating oils of high viscosity index and low pour point, it is possible to use three principal methods:

The first consists of intensifying the refining of the mineral oils; but in this case, oils of high viscosity index can only be obtained if the viscosity remains low; it is thus possible to obtain the grade SAE -W-20, but if a change be made to gnade SAE 30, one 'is confined to the oils SAE 20-W-30.

According to the second method, recourse is had to synthetic oils, but according to current techniques, with oils obtained from olefins, it is not possible to attain the grades W40 or 10-W-50 and with ester-type oils one is confined to 5-W-20 and l0-W-20.

Finally, the attempt can be made to use additives for improving the viscosity index and the pour point of mineral or synthetic-based oils.

The additives at present used for the purpose are, generally speaking, polymers or copolymers of high molecular weight. They fail to give full satisfaction because they stand up badly to oxidation and shearing forces, especially those which appear in the systems of gear transmission or in piston pumps for hydraulic circuits. Now, technical development in these fields takes the form of ever more severe mechanical stresses. Indeed, we are at present faced with two kinds of additive improving the viscosity index: on the one hand those which are of the polyisobutylene type whose shearing strength is acceptable, as they yield in the sonic breakdown test viscosity gradients in the region of 24% for a 10% solution in a mineral-oil, but they deteriorate through oxidation and moreover those which, being of the polymethacrylate type, fumarate etc., are more resistant to oxidation, but do not withstand shearing, the drop in viscosity in the sonic breakdown test being in the region of 50% Furthermore, the present additives improving the viscosity index greatly increase the viscosity of the oils at low temperature, so that there is a considerable discrepancy at 17.8 C. between the measured viscosity and the viscosity extrapolated by means of the ASTM viscosity-temperature chart.

It is known that it is possible to prepare oils by the copolymerisation of ethylene and propylene, whose molar ratio is between 1.5 and 0.43 in the presence of catalysts ice consisting of organo-metallic compounds or organic compounds of metals. The catalysts which may be used are selected from mixtures of a heavy metal compound se lected from Subgroups B of Groups IV to VII or Group VIII of the Periodic Table, and one of the following:

(a) An organic compound of a metal of Groups I to IV, preferably Group II or III, of the Periodic Table. (b) A metal hydride or organometallic hydride. (c) A halogenated organo-metallic compound. Preferably the catalyst comprises tri-alkyl aluminum and titanium tetrachloride, the molar ratio TiCl /R Al (R=a1kyl) being between 1:1 and 10:1 preferably about 3:1. The catalyst may if desired be prepared in situ, in a solvent comprising a saturated hydrocarbon e.g. heptane and/or an aromatic hydrocarbon e.g. xylene and in a quantity such that the ratio by weight:

solvent total dissolved polymer is between 10/7 and 1/ 3. Copolymerisation is carried out in an inert atmosphere, at atmospheric or higher pressure, at a temperature between 40 C. and +80 C. and for preference from -10 C. and +20 C. After decomposition and elimination of the catalytic complex, the polymer is filtered and the solvent evaporated. Hydrogenation on nickel may be carried out under the usual conditions.

Distillation under vacuum (pressure lower than 1 mm. Hg) makes it possible to collect inter alia the fraction distilling above 450 C. (boiling point converted to that at normal pressure). The mean molecular weight of the fraction distilling above 450 C. thus obtained is in the region of 1000 to 3000.

The applicants have discovered that these products, when added to mineral and/or synthetic oils of the ester type, make it possible to prepare excellent compositions, characterized by among other properties, their qualities of viscosity, their pour points, their resistance to oxidation and heat, their total shearing strength etc.

These compositions may contain from 1 to 70% by weight of oily ethylene-propylene copolymer.

These synthetic oils of the ester type may for preference be di-2-ethyl-hexyl, di-decyl, or di-nonyl adipate or sebacate, as well as the esters of pentaerythritol.

The following examples which are given by way of illustration and in no way restrictively will better show the scope and importance of the invention:

EXAMPLE 1 (l) A mineral base oil A and the heavy fraction of an ethylene-propylene copolymer as defined above were used. They had the following characteristics.

(2) The following compositions were prepared: C 97% oil A and 3% copolymer.

C oil A and 25% copolymer. C 60% oil A and 40% copolymer.

C1 C2 Cs Viscosity at 37.8 0., est 37. 50 114. 4 235 V1scos1ty at 98.9 0., est 6. 11 14. 33 25. 89 Viscosity index 119 126 126 Pour point, C 12 -12 -15 Flash point open vessel, C 228 228 235 They make it possible to plot the vicosity curves 37.8 C. and n98.9" C. as well as the viscosity indices (V.I.) as a function of the percentage of copolymer; these curves (FIG. 1) show that the improvement in the viscosity index is obtained very quickly, and is very largely constant from copolymer onwards; thickening effect is more progressive. Curve 1 is that of the 1 37.8 C. as a function of the percentage of copolymer.

Curve 2 is that of the viscosity of 1 98.9" C. as a function of the percentage of copolymer, curve 3 is that of the V1. as a function of the copolymer.

(3) The composition C which represents a motor oil SAE -W-40, was subjected to tests making it possible to appreciate the shearing stability.

(a) Stability determined by the test termed sonic breakdown test This consists of subjecting the oil to shearing forces created by a 10 kcs. oscillator at 200 watts and 98.9 C. for a determined period:

The result is expressed by:

1 being the viscosity at 98.9 C. before the test. 77 being the viscosity at 980 C. after the test.

By way of comparison, the behaviour of the same oil A was examined with a commercial additive (add.) consisting of a polymethacrylate of high molecular Weight, the quantity of additive added representing 5.6% by weight of the oil being that which made it possible to obtain viscosities and a viscosity index comparable with those of composition C The following results were obtained:

02 Oil A plus add.

Length of test, minutes 60 25 60 Percent drop of viscosity 0.04 0.44 15 22 (b) Mechanical shearing stability (c) Stability in the test with a Peugeot 204 vehicle This test consists of subjecting the oil to the mechanical shear found in the gears of the gear box and the differential of a Peugeot 204 vehicle, type XK. The engine is mounted on the bench and the test lasts 50 hours.

By way of comparison, use was also made of oil A with 5.6% of the additive previously specified.

The curves of FIGS. 2 and 3 show, as a function of the length of operation, in hours, for the composition C and for oil A with the commercial additive, on the one hand the variations in the viscosity index (V.I.) and on the other the variations of Afl/flo:

fl viscosity at time tviscosity at initial time. no viscosity at inital time.

the viscosities being measured at 98.9 C.

EXAMPLE 2 With the copolymer mentioned in Example 1 and with a base oil B the following oils were prepared:

B containing 15% copolymer. B containing 32% copolymer. B containing copolymer.

by weight in relation to the base oil B. The following results were obtained:

B B1 132 B Viscosity at 378 0., cst 8. 25 18. 84 50. 81 74. Viscosity at 98.9 (3., c 2. O6 4. 2 8. 5 11.2 Viscosity index 29 137 133 Pour point, C 42 -57 54 ---51 Flash point open vessel, C 142 156 158 160 EXAMPLE 3 To ascertain the resistance to oxidation and t0 the heat of the copolymer corresponding to the invention a product was taken of mean molecular weight 1500, and it was subjected to differential thermal analysis under an atmosphere of nitrogen and an oxidising atmosphere. By way of comparison, the same test was carried out on a commercial additive consisting of a polyisobutylene of mean molecular weight 1000.

The measurements were carried out with a commercial apparatus with a linear heating system of 1 C. per minute, and a silicone oil as reference substance.

The thermal stability is characterised by the temperature from which the product placed under an atmosphere of nitrogen gives a thermal effect. It manifests itself with polyisobutylene from 285 C. whereas with the polymer corresponding to the invention it only appears at 345 C., or a gain in thermal stability of 60 C.

In an oxidising atmosphere, for the two products compared, the resistance to oxidation amounts to 135 and 315 C. or a gain of 180 C. in favour of the copolymer corresponding to the invention.

EXAMPLE 4 Viscosity at 98.9 C. 378 0. Measured Extrapolated The effective viscosity of the oil H1 at 17.8 C., very difierent from that furnished by extrapolation, is three times the viscosity of the oil H2.

EXAMPLE 5 A synthetic oil was taken consisting of bis 2- ethylhexyl adipate and the copolymer mentioned in Example 1, according to variable proportions.

The following results were obtained:

Percent weight of oil 66 9 5 Percent weight of copolymer 33: l 8

Viscosity at 17.8 0., extrapolated, est 1 5'0 0 Viscosity at 37.8 C., est 0 1.18 8 18 Vlscoslty at 08.0" 0., cst 11. 40 14. 20 2' 30 iscosity index 145+ I42 112; liour point, C 54 54 -60 (,rade SAE 10-W-30 10-W-40 This clearly shows the improvement in the viscosity index; the obtaining of the grades SAE 1=0-W-30 and 10-W-40 is possible.

EXAMPLE 6 6 carried out with the apparatus model CCSl sold by the firm of Cannon Instrument Co., Philadelphia, USA.

The following results were obtained:

5 D D] Dz D A synthetic oil was taken consisting of bis-Z-ethyl-hexyl sebacate; to it was added the copolymer referred to in :2 g g aggggjjj i3 3 j3 P 1;, -39 -45 Example 1. The following results were obtained. ggggg i Percent Weight of oil 77. 5 68. 5 65.5 10 Percent weight of copolymer 22.5 51.5 34.5 The exceptionally low pour points of the ternary IIllX- Viscosity at -17.s 0., extrapolated, est-.. 1, 300 1, 900 2, s00 W111 be noted- Viscosity at 375 0., est 61.6 90.2 107.2 EXAMPLE 8 Viscosity at 988 0., cst 11.5 16.0 18. 0 u VISQOSIW Index 149 146 143 It 1s likewlse possible to prepare 011s for gear boxes and Four point, C 57 -54 -54 Flash oint open vessel, 235 236 236 rear axles having a viscosity which varies but little as a Grade SAE function of the temperature, such as mixtures E and E consisting of a mineral oil G, type 150 neutral, and co- By way of compar son, the same 011 was m1xed w1th Bright polymer, according to the f ll i percentages; Stock solvent, WhlCh is the mmeral 011 having the best viscosity index in relation to its viscosity. G E! E2 The following results are obtained:

Mineral oil G 100 50 33 Oopolymer 0 5 67 25332? W522i 3 51;551:5512" 36 26 solvent 100 64 74 These mixtures have the following characteristics: Viscosity at37.8 0., est 12. 61 524 90.7 139.6 Viscosity at 98.9 0., cst 3. 32 32. 3 11.65 15.1 G E1 E2 Viscosity index 154 98 121 114 Pour point, 0-... 6O 12 21 18 Viscosity at 989 C., cst 5. 37 25.0 50 Grade SAE 5 W 20-W-30 SAE Viscosity at 17.8 C. (extrapolated), 0st 21.000 iscosity iglgeg. 10g 1g 1%(2) r in The thickening by the viscous o1l therefore causes a 3 G 1 'gdei AE 250 rapid drop in the viscosity index of the composition and, in the best case, it is definitely only possible to obtain grade Th present i ti h b d rib d b :way of SAE 20-W-30. explanation and in no sense restrictively. Any useful m0- A determmation was made of the shearing stability difications may be made to it without departing from its of the composition containing 69% oil and 31% copoly- 35 scope. me r, 1n a Rosch injector type KB SA 53/1 under very What is claimed is: stringent conditions: 1. A lubricating composition comprising a major Temperature of oil 0 amount of a base oil1 whichi does not mic; Ehe visiosity re- Injector inlet pressure 250 atmospheres 40 'i f g a i t1 i e Se p Injector outlet pressure 1 atmosphere .conS1?tmg o 01 a Syn e 10 es er u mg 011 and a viscosity 'lIIlPIOVlHg amount of at least 1 wt. cycles per hour percent and suflicient to lmpart the v1scos1ty requirements The following results were obtalned: of a multi grade oil to the base oil of an oily copolymer Length of test in hours 0 5 10 20 40 50 Viscosity of oil at:

37.8 0., est 92.80 92.72 92.52 92. 47 92. 41 92. 34 92.07 9s. 9 0., est--- 15.82 15.81 15.69 15.66 15.64 15.61 15.57 Viscos1ty index 145 145 145 144 144 144 144 Acid number 0.26 0.26 0.26 0.20 0.26 0.20 0.29 Grade of oil SAE 10-w-40 10-W-40 10-W-40 10-W-40 10-W-40 10-W-40 10-W-40 The compositions bis-2-ethyl-hexyl sebacate copolymer liquid fraction boiling above 450 C. (at normal presaccordlng to the mvention therefore posses perfect shearsure) and having a mean molecular weight of about 1000 mg Strength to 3000 obtained from the copolymerization of ethylene As regards resistance to oxidation, this is the outcome, 5 and propylene using a molar feed ratio of between 1.5- on the one hand of the well known stability of base oils 0.43:1 respectively, in an inert atmosphere at a temperaof ester type and the stability of the copolymer shown by ture of between -40 C. and +80 C., in the presence of Example 4. a catalyst comprising a mixture of tri-allkyl aluminum and titanium tetrachloride in a mole ratio of between 1:l EXAMPLE 7 60 and 10m Ternary mixtures were taken consisting of bis-2-e hyl- 2. A composition as claimed in claim wherein the cataheXyl p a mineral Oil D of yp 100 neutral Solvent lyst is prepared in situ in a solvent selected from the group and the copolymer shown in Example 1, according to the consisting of a saturated hydrocarbon and an aromatic following percentages by weight: hydrocarbon so that the ratio by weight of solvent to total dissolved copolymer is 1.43-0.33z1. D D2 D3 3. A composition as claimed in claim 1 wherein the co- Bis-2-ethyl-hexyl 0 5 15 25 polymerisation is carried out at a temperature of between Mineral oilD 1 75 5 55 10 C and +20 C Copolymer 0 2 2O 20 4. A compositlon as cla1med 1n cla1m 1 WhlCh contains A measurement was made of the viscosity at 17.8 C. 1 to 70 weight percent of the copolymer fraction. in the cold cranking simulator; this method is shortly to 5. A composition as claimed in claim 1 wherein the to become an ASTM method under the designation synthetic ester lubricating oil is selected from the group DXXXX-67T; it provides a laboratory process for deterconsisting of di-Z-ethyl hexyl adipate, di-decyl adipate, diming the apparent viscosity of an engine oil at l7.8 C. nonyl adipate, di-2-ethyl hexyl sebacate, di-decyl sebacate with a high proportion of shear. The measurements were and di-nonyl sebacate.

References Cited UNITED STATES PATENTS 2,190,918 2/1940 Goethel et a1 252-59 2,327,705 8/1943 Frolich et al. 25259 2,889,314 6/1959 Fritz 260683.15

8 3,057,801 10/1962 Wilgus 252-59 3,389,087 6/1968 Kresge et al. 252--59 3,474,157 10/1969 White et a1 260683.15

5 DANIEL E. WYMAN, Primary Examiner W. H. CANNON, Assistant Examiner U.S. Cl. X.R. 260683.15 D