GB2091288A - Traction Fluid Based on Mineral Oil - Google Patents

Abstract

A traction fluid having a lubricant base comprises a mineral oil composition which contains (i) a saturates fraction having at least 35% thereof by volume of multi-ring components of at least three rings, and (ii) at least 15% by weight of said composition of an aromatics fraction having at least 40% thereof by volume of multi-ring components of at least two rings at least one of which is an aromatic ring. The aromatics fraction preferably comprises naphthalenes, acenaphthenes, fluorenes, phenanthrenes, mononaphthene benzenes and dinaphthene benzenes. The saturates fraction preferably comprises components having a ring or rings of five or six members. The weight ratio of the aromatics fraction to the saturates fraction is preferably at least 0.4:1.

Description

SPECIFICATION Traction Fluid Based on Mineral Oil This invention relates to a traction fluid based on mineral oil.

The term "traction fluid" is used to identify a class of lubricants that give superior performance in traction drives. A traction drive transfers force from one rotating shaft to another through a rolling contact. Efficient transfer requires that a minimum amount of slippage occurs. This property is measured by the traction coefficient which is defined as force transmitted divided by the normal force which keeps the rolling members in contact.

The coefficient of traction as defined above, has been one of the prilne measurements used in defining useful traction fluids. Various studies have been made attempting to define the type of structures associated with higher traction properties. Thus, some of the more suitable structures which have been reported include U.S. Patent 3,411,369 which discloses fused, saturated carbon containing rings; U.S. Patent 3,440,894, which discloses organic compounds containing a saturated carbon containing ring or an acyclic structure having at least three quaternary carbon atoms; U.S. Patents 3,595,796 and 3,598,740 disclose the use of selected naphthenes and branched paraffins; and U.S.

Patent 3,843,537 discloses the use of naphthenes, partially saturated precursors of naphthenes, hydrorefined mineral oils, polyolefins and branched paraffins.

Generally, the structures defined in the literature as having good traction properties have not included aromatic constituents. This is exemplified by U.S. Patents 3,595,796; 3,598,740 and 3,843,537 which indicate the general undesirability of aromatic unsaturation as it relates to traction properties and the need to limit aromatic content to very low levels.

Detailed Description of the Invention Now in accordance with this invention it has surprisingly been found that selected mineral oil compositions which contain significant amounts of aromatic constituents are particularly useful as traction fluid lubricants. More particularly, this invention is directed to a traction fluid having a lubricant basestock which comprises selected mineral oil compositions containing a saturate hydrocarbon fraction having at least about 35% by volume of multiring components of at least three rings and an aromatic fraction which comprises at least about 1 5% by weight of said composition and which fraction contains at least about 40% by volume of multiring aromatic components.

The ability to ascertain the surprising attributes of aromatic constituents in traction fluids was in part the result of a newly-developed technique for evaluating traction properties. This technique involved development of a traction index which is based on the rolling torque generated and the amount of slippage found in the rolling contact. Further details of this technique will be described in detail later on in the specification.

The mineral oil compositions on which the traction fluids of this invention are based are any of the commonly available petroleum basestock materials which comprise a range of different hydrocarbons of naphthenic, aromatic and paraffinic content. The selected mineral oil compositions are obtained from the starting mineral oils by separation into fractions having specified saturated and aromatic portions as will hereinafter be defined. Generally, this fractionation will be made by a technique such as thermal diffusion, a known separation procedure which is described for example in "Composition and Oxidation of Petroleum Fractions" by G. E. Cranton in Thermochemica Acta, 14 (1976) 201-208. Other techniques which can be used to produce the desired fractions can also be used.

The selected traction fluids of this invention contain lubricant basestock materials which are mineral oils selectively fractionated to yield a composition which contains a saturate fraction and an aromatic fraction. Generally the weight ratio of aromatics to saturates will be at least about 0.2:1, preferably at least about 0.3:1 and more preferably at least about 0.4:1. The saturate fraction will generally have a significant portion, i.e. greater than about 35% by volume, and preferably greater than about 50%, made up of multiring components of at least three rings. More particularly, the saturate fraction will have a volume ratio of multiring (three or more rings) to 12-ring components of at least 0.5:1, preferably at least about 1:1 and more preferably at least about 2:1.The aromatic fraction will generally comprise at least about 15% by weight of the composition, preferably at least about 20% and more preferably at least about 25% by weight. The aromatic fraction will contain at least about 40% by volume of multiring components having two or more rings, at least one of which is an aromatic ring, preferably at least about 60% and more preferably at least about 80% by volume.

The multiring portion of the aromatic fraction is generally comprised of naphthalenes, acenaphthene, fluorenes, phenanthrenes, mononaphthene benzenes and dinaphthene benzenes. It is understood that branched or substituted ring components are also included in the defined aromatic fraction. The saturate fraction will generally be comprised of 5 and 6 membered ring structures having various branched substituents. Generally, both the saturate and aromatic fraction will be comprised of a mixture of compounds each containing about 6 to about 100 carbon atoms. Each fraction will generally contain a variety of branched substituents and may contain small amounts of sulfur and nitrogen content.

In addition to the lubricant basestocks of this invention, additives designed to enhance specific properties of the traction fluids can be added to the composition. Such additives include, for example, V.l. improvers, antiwear agents, corrosion inhibitors, antioxidants, dispersants, etc. Generally additive amounts of up to about 20%, preferably up to about 10% by weight of the fluid may be used in the traction fluids.

As indicated earlier, the ability to ascertain the surprising traction properties resulting from materials containing significant aromatic constituents was aided by a new technique for evaluating such traction properties. A traction index (TI) which is based on the rolling torque generated and the amount of slippage found in the rolling contact was formulated to rate the different fluid materials.

Table I shows the parameters used in rating the material and as defined therein:

with the different torque and slip factors used in ascertaining TI being further defined in said Table I.

The traction data was obtained on a modified Roxanna four ball wear tester as described in ASTM D 2266-67. The traction tester used had a Brown modification consisting of a hydraulic cylinder which applied a normal load and an air bearing which allowed for accurate frictional measurements.

Additionally, the tester had a machined pot which held a conforming race and allowed rolling contact to occur rather than the sliding contact required by the ASTM method (the bottom three balls in the four-ball pyramid were allowed to roll on a conforming race). This tester was evaluated as a means for determining the traction properties by selecting a series of materials whose coefficients of traction had been previously determined and measuring their traction properties on such a tester. As indicated in Table II, the Traction Index (TI) gave a linear correlation with literature traction coefficients and was therefore a valid method of evaluating traction properties.

Further details and illustrations of this invention will be found in the following examples.

Example 1 A paraffinic Solvent 150 Neutral mineral oil having a viscosity of 12.3 cSt at 650 C, n, of 1.4756, and a Vl (viscosity index as determined by ASTM D2270) of 90 was used as the feed material.

The feed material was fractionated using batch thermal diffusion in laboratory scale units of the vertical cylinder type with each column furnished with ten ports with a mean slit diameter of 0.03 cm.

The total volume of each unit was 30 ml. The inner wall of the annulus was cooled by water to 57.2- 65.60C and the outer wall was electrically heated to 115.6-1 37.80C. Operation involved filling the column with feed, allowing a period of time (about 1 4 days) for separation and sampling the ports starting from the top. This was repeated until about 12 ml. was obtained for each fraction.

The resulting fractions were evaluated for traction properties and the results given in Table Ill.

Example 2 A naphthenic Solvent 60 Neutral mineral oil having a viscosity 4.38 cSt at 650C, n D of 1.4747 and a Vl of 68 was used as the feed material and fractionated in the same manner as the sample in Example 1.

The resulting fractions were evaluated for traction properties and the results given in Table IV.

Example 3 A paraffinic Solvent 60 Neutral mineral oil having a viscosity of 4.60 cSt at 650C, n D of 1.4748 and a Vl of 37 was used as the feed material and fractionated in the same manner as the sample in Example 1.

The resulting fractions were evaluated for traction properties and the results given in Table V.

These results show that the fractions identified in Tables Ill, IV and V as ports 8 to 10 are particularly suitable as traction fluids. Comparing these data to those of a current synthetic traction fluid (see Table II, Santotrac.50), shows that equivalent or better traction properties are achieved at comparable viscosities.

Information regarding the analyses of the different fractions tested can be found in Tables Vi, Vll and VIII.

Table I Parameters for Rating Oils by Traction Tester' Good Poor Parameter Symbol Performance Performance Rating Factor Torque: 150 kg, 115 cm/sec, T3000 > 220 < 150 650C (g-cm) Torque Factor, 150 kg TF 1 O (T3000-1 50)170 Torque: 150 kg, 7.7 cm/sec, T200 > 220 < 150 650C (g-cm) Torque Speed Dependence Ts 1 0 (1-(T200-T3000)/200 % Slip: 5 kg, 192 cm/sec, S5 > 2.5 < 1.0 650C % Slip Factor, 5 kg S5F 1 0 S2.5 % Slip 50 kg, 192 cm/sec, S50 NO > 1.0 650C Slip Load Dependence ASR 1 O (S5-S50)/S TF+Ts+S5F+ASR Traction Index (TI) 1 0 4 (1) A good performance will give a TI of L1 while a poor performance will give a TI of ca. 0.

Table II Data for Correlating Traction Tester With Literature Viscosity Traction Traction Coefficient Lubricant (cSt, 650C) Index (at 102 cm/sec) MCT 10 Base (Solvent 150 neutral) 12.0 0.57 ca. 0.045 Santotrac 50 (Monsanto) 12.8 1.11 0.095 Oleic Acid 9.7 0.22 0.036 Ethylene Glycol 4.1 0.15 0.007 Cyclohexanol 6.7 0.49 0.056 Diethylene Glycol 5.5 0.39 0.031 Santotrac EP-2 (Monsanto) - 1.16 0.108 TABLE III Physical and Traction Properties of Thermal Diffusion Fractions from Paraffinic Solvent 150 N Physical Properties Traction Properties Fraction Viscosity T200 T3000 No. no (cST, 65 C) VI (g-cm) (g-cm) SS SSO TF TS SSF #SR 77 Feed 1.4823 12.3 89.0 192.0 188.5 1.06 0.60 0.55 0.98 0.42 0.43 0.60 3 1.4629 8.2 124.0 187.5 185.7 0.82 0.00(a) 0.22 0.89 0.33 1.00 0.61(b) 6 1.4800 11.8 89.0 191.4 186.3 0.98 0.60 0.52 0.97 0.39 0.39 0.57 7 1.4889 16.2 70.0 196.3 192.2 1.07 0.40 0.60 0.98 0.43 0.63 0.66 8 1.4998 25.2 10.6 195.1 200.8 1.43 0.04 0.73 1.03 0.58 0.97 0.83 9 1.5108 65.0 8.7 199.7 215.4 2.33 0.08 0.93 1.08 0.93 0.97 0.98 10 1.5163 82.0 -118.7 199.5 229.7 2.88 0.07 1.14 1.15 1.15 0.98 1.11 (a) S100 = 0.20.

(b) Tl for TP, TS, SSF = 0.48.

TABLE IV Physical and Traction Properties of Thermal Diffusion Fractions from Naphthenic Solvent 60 N Physical Properties Traction Properties Fraction Viscosity T200 T3000 No. no (cST, 65 C) VI (g-cm) (g-cm) SS SSO TF TS SSF #SR 77 Feed 1.4747 4.38 68.0 203.7 180.8 0.92 0.24 0.44 0.89 0.37 0.74 0.61 8 1.4898 5.70 15.0 198.8 183.6 1.15 0.18 0.48 0.92 0.46 0.84 0.68 9 1.5032 7.80 -0.7 228.5 191.0 1.45 0.06 0.59 0.81 0.58 0.96 0.74 10 1.5172 14.30 -64.3 196.2 196.4 2.95 0.04 0.66 1.01 1.18 0.99 0.96 TABLE V Physical and Traction Properties of Thermal Diffusion Fractions from Paraffinic Solvent 60 N Physical Properties Traction Properties Fraction Viscosity T200 T3000 No. no (cST, 65 C) VI (g-cm) (g-cm) SS SSO TF TS SSF #SR 77 Feed 1.4748 4.60 37.0 204.9 175.4 0.80 0.36 0.36 0.85 0.32 0.55 0.52 7 1.4813 5.40 57.0 202.4 181.0 1.02 0.32 0.44 0.89 0.41 0.69 0.61 8 1.4932 6.75 21.0 207.3 187.1 1.22 0.12 0.53 0.90 0.49 0.90 0.71 9 1.5084 10.30 -18.5 195.2 189.7 1.51 0.04 0.57 0.97 0.50 0.97 0.78 10 1.5212 20.50 -49.1 198.6 196.6 3.93 0.04 0.67 0.99 1.57 0.99 1.06 Table VI Analysis of Paraffinic Solvent 150 N Thermal Diffusion Fractions(2)

Silica Gel Analysis Feed Port #3 Port #7 Port #8 Port #9 Port #10 Saturates, wt. % 80.6 90.7 75.3 71.4 88.4 66.0 Aromatics, wt. % 15.5 7.9 20.7 23.7 26.3 27.3 Polar Compounds, wt. % 3.9 1.4 4.0 4.9 5.3 6.7 Recovery, wt. % 100.0 100.0 100.0 100.0 100.0 100.0 Mass Spec Analysis Saturates (LV % on Saturates) Paraffins 23.7 40.66 5.68 1.85 0.17 2.03 1-Ring 26.96 40.81 27.10 14.43 0.00 7.56 2-Ring 18.17 14.19 29.97 24.59 19.91 16.23 3-Ring 10.95 2.19 19.83 22.23 20.63 18.11 4-Ring 11.80 0.84 11.25 24.86 37.25 30.61 5-Ring 5.16 0.16 3.35 8.09 14.33 15.37 6-Ring 2.34 0.45 1.49 2.44 5.50 7.69 Mono-aromatics 0.92 0.71 1.32 1.50 2.22 2.39 100.00 100.00 100.00 100.00 100.00 100.00 Table VI (Continued)

Feed Port #3 Port #7 Port #8 Port #9 Port #10 Aromatics (LV % on Aromatics) Alkyl Benzenes 27.30 60.65 19.74 12.71 8.96 9.56 Mononaphthene Benzenes 20.95 26.45 25.82 19.70 14.18 12.30 Dinaphthene Benzenes 18.30 5.73 23.22 24.71 22.77 19.86 Naphthalenes 8.87 3.97 9.31 10.35 10.00 10.68 Acenaphthenes 7.87 1.65 7.66 10.07 11.47 11.40 Fluorenes 6.88 0.85 5.89 8.72 11.22 11.95 Phenanthrenes 3.82 0.35 2.50 4.21 6.23 7.50 Naphthenephenanthrenes 0.69 0.03 0.06 0.79 1.88 2.59 Pyrenes 0.45 0.00 0.30 0.73 1.24 1.64 Chrysenes 0.31 0.00 0.20 0.91 1.05 0.85 Perylenes 0.29 0.00 0.02 0.14 0.65 1.18 Dibenzanthracenes 0.17 0.00 0.05 0.11 0.26 0.58 Benzothlophenes 0.41 0.00 2.07 2.03 1.48 0.99 Dibenzothiophenes 0.80 0.00 0.73 1.68 2.44 2.05 Naphtobenzothiophenes 0.00 0.00 0.00 0.00 0.05 0.40 Unidentifiable Aromatics 2.90 0.32 1.81 3.16 6.11 6.47 100.00 100.00 100.00 100.00 100.00 100.00 Summary From Mass Spec Plus Silica Gel Analysis Saturates (wt. % on Total) Paraffins 19.10 36.88 4.28 1.32 0.12 1.34 1-2 Ring 36.37 49.89 42.97 27.86 13.62 15.70 3-6 Ring 24.38 3.30 27.05 41.14 53.16 47.37 Mono-aromatics 0.74 0.64 0.99 1.07 1.52 1.58 Aromatics (wt. % on Total) Single Ring 10.32 7.33 14.24 13.54 12.07 11.39 Multi-Ring 4.55 0.54 5.38 8.54 11.57 13.21 Sulphur 0.19 0.00 0.70 0.88 1.04 0.94 Unidentifiable Aromatics 0.45 0.03 0.37 0.75 1.61 1.77 Polar Compounds (wt. % on Total) Total 100.00 100.00 99.89 100.00 100.00 100.00 (a) The wt. % recovery is adjusted 100.0% by proportional adjustement to each fraction.

Table VII Analysis of Experimental Paraffinic Solvent 60 N Thermal Diffusion Functions(a)

Feed Port #3 Port #8 Port #9 Port #10 Silica Gel Analysis Saturates, wt. % 80.0 91.3 71.6 64.3 55.7 Aromatics, wt. % 18.4 8.2 26.3 33.1 40.4 Polar Compounds, wt. % 1.8 0.5 2.0 2.5 3.9 Recovery, wt. % 100.0 100.0 99.9 99.9 100.0 Mass Spec Analysis Saturates (LV % on Saturates) Paraffins 29.52 48.49 6.17 2.98 1.79 1-Ring 28.28 36.58 21.37 9.49 4.18 2-Ring 21.69 12.66 37.39 25.59 13.26 3-Ring 12.84 1.17 27.11 37.22 28.69 4-Ring 7.66 0.93 5.88 19.68 36.33 5-Ring 0.00 0.00 2.07 5.05 15.75 6-Ring 0.00 0.00 0.00 0.00 0.00 Mono-aromatics 0.00 0.16 0.00 0.00 0.00 100.00 100.00 100.00 100.00 100.00 Aromatics (LV % on Aromatics) Alkyl Benzenes 30.34 78.62 16.39 8.79 5.64 Mononaphthene Benzenes 22.74 14.05 31.81 21.85 13.26 Dinaphthene Benzenes 19.05 1.83 23.51 33.04 31.08 Naphthalenes 8.81 2.75 11.47 9.72 10.04 Acenaphthenes 5.97 1.53 6.17 9.18 10.48 Fluorenes 4.46 0.28 3.89 6.69 10.48 Phenanthrenes 1.58 0.37 1.31 2.35 3.70 Naphthenephenanthrenes 0.16 0.10 0.00 0.26 1.20 Pyrenes 1.15 0.42 1.15 1.32 1.47 Chrysenes 0.34 0.00 0.00 0.44 1.20 Perylenes 0.09 0.03 0.00 0.01 0.45 Dibenzanthracenes 0.01 0.00 0.01 0.01 0.02 Benzothiophenes 3.10 0.00 4.28 2.85 2.28 Dibenzothiophenes 1.47 0.00 0.00 3.28 5.83 Naphthobenzothiophenes 0.04 0.00 0.00 0.00 0.31 Unidentifiable Aromatics 0.68 0.02 0.01 0.22 2.56 100.00 100.00 100.00 100.00 100.00 Table VII (Continued)

Summary From Mass Spec Plus Silica Gel Analysis Feed Port #3 Port #8 Port #9 Port #10 Saturates (wt. % on Total) Paraffins 22.62 44.27 4.42 1.92 1.00 1-2 Ring 39.98 44.96 42.07 22.56 9.71 3-6 Ring 16.40 1.92 25.10 39.83 44.99 Mono-aromatics 0.00 0.15 0.00 0.00 0.00 Aromatics (wt. % on Total) Single Ring 13.27 7.75 18.86 21.08 20.19 Multi-Ring 4.15 0.45 6.31 9.92 15.77 Sulphur 0.85 0.00 1.13 2.03 3.40 Unidentifiable Aromatics 0.13 0.00 0.00 0.07 1.83 Polar Compounds (wt. % on total) 1.60 0.50 2.00 2.50 3.90 Total 100.00 100.00 99.89 99.91 99.99 (a) The wt. % recovery is adjusted to 100.0% by proportional adjustement to each fraction.

Table VIII Analysis of Naphthenic Solvent 60 N Thermal Diffusion Fraction(a)

Feed Port #3 Port #9 Port #10 Silica Gel Analysis Saturates, wt. % 80.7 93.3 62.8 57.1 Aromatics, wt. % 17.6 5.9 34.0 38.4 Polar Compounds, wt. % 1.7 0.8 3.1 4.5 Recovery, wt. % 100.0 100.0 99.9 100.0 Mass Spec Analysis Saturates (LV% on Saturates) Paraffins 34.57 56.81 2.44 1.03 1-Ring 25.80 33.06 9.40 3.29 2-Ring 17.42 8.11 21.99 10.68 3-Ring 10.29 0.80 28.53 34.50 4-Ring 8.21 0.70 27.43 32.91 5-Ring 3.71 0.34 10.21 17.54 6-Ring 0.00 0.00 0.00 0.00 Mono-aromatics 0.00 0.17 0.00 0.06 100.00 100.00 100.00 100.00 Table VIII (Continued)

Feed Port #3 Port #9 Port #10 Aromatics (LV % on Aromatics) Alkyl Benzenes 29.31 79.96 9.67 5.82 Mononaphthene Benzenes 20.28 13.32 18.48 12.22 Dinaphthene Benzenes 18.20 1.51 27.82 27.05 Naphthalenes 9.01 2.76 10.33 10.45 Acenaphthenes 7.40 1.33 10.91 12.44 Fluorenes 5.74 0.22 8.60 11.36 Phenanthrenes 2.20 0.24 3.42 4.43 Naphthenephenanthrenes 0.35 0.00 0.39 1.17 Pyrenes 0.96 0.44 0.89 1.02 Chrysenes 0.93 0.02 1.48 1.61 Perylenes 0.16 0.00 0.05 0.66 Dibenzanthracenes 0.01 0.00 0.00 0.03 Benzothiophenes 1.62 0.00 2.27 1.68 Dibenzothiophenes 2.37 0.00 4.35 6.17 Naphthobenzothiophenes 0.09 0.05 0.00 0.33 Unidentifiable Aromatics 1.38 0.17 1.35 3.58 100.00 100.00 100.00 100.00 Summary from Mass Spec Plus Silica Gel Analysis Saturates (wt. % on Total) Paraffins 27.90 53.00 1.53 0.59 1-2 Ring 34.88 38.41 19.71 7.98 3-6 Ring 17.92 1.72 41.55 48.51 Mono-aromatics 0.00 0.16 0.00 0.03 Aromatics (wt. % on Total) Single Ring 11.93 5.59 19.03 17.31 Multi-Ring 4.71 0.30 12.26 16.58 Sulphur 0.72 0.00 2.25 3.14 Unidentifiable Aromatics 0.24 0.01 0.46 1.37 Polar Compounds (wt. % on Total) 1.70 0.80 3.10 4.50 Total 100.00 99.99 99.89 100.00 (a) The wt. % recovery is adjusted to 100% by proportional adjustement to each fraction.

Claims (12)

Claims

1. A traction fluid having a lubricant base comprising a mineral oil composition which contains (i) a saturates fraction having at least 35% thereof by volume of multi-ring components of at least three rings, and (ii) an amount, which is at least 15% by weight of said composition, of an aromatics fraction having at least 40% thereof by volume of multi-ring components of at least two rings at least one of which is an aromatic ring.

2. A traction fluid as claimed in claim 1 , wherein the weight ratio of aromatics fraction to saturates fraction is at least 0.2:1.

3. A traction fluid as claimed in claim 2, wherein said ratio is at least 0.3:1.

4. A traction fluid as claimed in any preceding claim, wherein the saturates fraction has a volume ratio of multi-ring to 1 - and 2-ring components of at least 1:1.

5. A traction fluid as claimed in claim 4, wherein said ratio is at least 2:1.

6. A traction fluid as claimed in any preceding claim, wherein said aromatics fraction has a volume ratio of multi-ring to 1- and 2-ring components of at least 1:1.

7. A traction fluid as claimed in any preceding claim wherein said aromatics fraction contains at least 60% by volume of multi-ring components.

8. A traction fluid as claimed in claim 7, wherein said aromatics fraction contains at least 80% by volume of multi-ring components.

9. A traction fluid as claimed in any preceding claim, wherein said aromatics fraction comprises at least 25% by weight of the composition.

10. A traction fluid as claimed in any preceding claim, wherein said aromatic fraction comprises naphthalenes, acenaphthenes, fluorenes, phenanthrenes, mononaphthene benzenes and dinaphthene benzenes.

11. A traction fluid as claimed in claim 1 and substantially as herein described.

12. A traction fluid as claimed in claim 1 and substantially as herein described with reference to any one of the Examples.