US2961408A - Power transmission mineral oil base fluids - Google Patents

Description

States Unite 13 Claims. (Cl. 25275) This invention pertains to improved functional fluids having good lubricating properties. More particularly this invention relates to mineral oil compositions for use in an apparatus by means of which mechanical forces are transmitted or absorbed such as in automotive and truck transmissions, hydraulic brakes, clutches, and various other mechanical equipment.

The smooth functioning of various power transmitting mechanisms particularly the more complicated automotive transmissions, fluid cooled brake mechanisms, oil lubricated wet clutches, planetary gears and hydraulic control mechanisms depends on adequate cooling and lubrication of the equipment. Rigorous requirements have been set up to quality fluids for this service which includes wide temperature stability at both high and low temperatures and a low pour point to insure proper pumpability and fluidity at low temperatures. The fluids must not have a detrimental effect on parts with which they come in contact such as metal surfaces e.g., copper and solid non-metallic surfaces such as organic resins and the like. They must possess desired frictional properties and, in some cases extreme pressure characteristics, to afford proper lubrication of gears, clutch plates and other parts of the mechanism in which they are used, such as automotive and truck equipment. Also, the fluids must not cause chattering, squawking, squealing or produce other noises caused by the frictional vibrations and/or stick-slip phenomenon of clutch plates or other parts of such mechanisms.

The prior art discloses various functional or power transmission fluids of the mineral oil or synthetic type (organic esters and polyethers) containing as the improving agents, various organic phosphates, fatty acids and their esters, halogenated compounds, polymers such as polyacrylates and the like. Compositions of this type are objectionable because of their inability to eliminate chattering and noises caused by frictional vibrations and/or stick-slip phenomenon of clutch plates and the like, particularly in equipment which is subjected to high speeds and temperatures.

-It has now been discovered that an excellent functional or power transmission fluid is provided, which satisfactorily meets the above requirements, which comprises a highly refined mineral oil base containing an additive combination, in critical amounts, of from about 0.05% to about 2%, preferably from about 0.1% to about 1% each of (1) a saturated aliphatic monocarboxylic acid having at least 18 carbon atoms in the molecule and (2) a product of neutralization between an alpihatic amine having at least 8 carbon atoms with a monoor dialiphatic acid pyrophosphate having at least 8 carbon atoms.

The long-chain aliphatic monocarboxylic acids include the saturated fatty acids of the C to C range such as stearic, arachidic, behenic, cerotic, montanic acids and mixtures thereof. Preferred are of saturated fatty acids having 18 to 26 carbon atoms such as stearic acid, be-. henic acid and cerotic acid and their mixtures.

The second essential additive is a product of neutraltent O."

2,961,408 Patented Nov. 22 1960 ization between an aliphatic amine having at least 8' carbon atoms and a monoor dialiphatic acid pyrophosphate the aliphatic group containing at least 8 carbon atoms. The aliphatic amines suitable for reaction with the aliphatic acid pyrophosphates are the primary and secondary saturated or unsaturated aliphatic amines having from'8 to 18 carbon atoms or mixtures of such amines. Typical of such amine reactants are octylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, octadecenylamine, octadecadienylamine, dioctylamine, didoceylamine, dioctadecylamine, dioctadecadienylamine and amines derived from fatty oils or fats such as cottonseed oil, soybean oil, coconut oil; lard, tallow, and the like, such as soyamine, cocoamine, tallowamine and mixtures thereof. Amines of this type are marketed by Armour and C0. under the trade name Armeen and include Armeen 12 and 12 D (dodecylamine), Armeen 14 and 14 D (tetradecylamine) Armeen 16 and 16 D (hexadecylamine) Armeen 18 and 18 D (octadecylamine), Armeen TD (mixture of tetradecyl, hexadecyl and octadecylamines), Armeen S and SD (mixtures of hexadecyl, octadecyl, octadecenyl and octadecadienyl amines). Preferred are the unsatu rated amines such as octadecadienylamine or Armeen S and Armeen SD. Polyamines are also included as reactants with the pyrophosphates. Polyamines' which are preferred are the N-alkyl alklene diamines which are prepared by the method described in U.S. 2,736,658 and and are marked by Armour and Co. under the trade name Duomeens such as Duorneen C, Duomeen S and Duomeen T, which are C1248 alkyl trimethylene dimonoand dioctyl pyrophosphate, monoand didodecyl pyrophosphate, monoand ditetradecyl pyrophosphate, monoand di-hexadecyl pyrophosphate, monoand di-octadecyl pyrophosphate, of which preferred are monooctyl pyrophosphate dioctyl pyrophosphate, monododecyl pyrophosphate, didodecyl pyrophosphate, mono-octadecyl pyrophosphate, dioctadecyl pyrophosphate and mixtures thereof.

The reaction betwen the amine and the pyrophosphate is exothermic and should be controlled so as to prevent decomposition. Generally'the temperature of the reaction should be between 50 and 100 C. and preferably below C. The mol ratio of the reactants should be within the ratio of 1 to 5 moles of the amine per mol of pyrophosphate compound, and preferably the reactants and reaction should be carried out under such conditions that the end product contains no free acid but can contain some free amine.

The amine-acid pyrophosphate reaction products in the molar proportions indicated in Table I were made as follows:

TABLE I Molar ratio of Temper- Example Amine Acid pyrophosphate amine ature,

to pyro- 0. phosphate I Armeen SD Dioctylpyrophosphate 2/1 70 do do 5/1 70 do do 2.2/1 70 Octadecy Lauryl pyrophosphate 5/1 80 annne. Dodecy1- Dodecyl pyrophos- 5/1 80' amine. phate. VI DuomeenTL- Dioctylpyrophosphate 4/1 70 35% oetadecenylamine and 45% oetadecadienylamine I Duomeen T=Oi iutrimethy1ene diamine derived trom tailow.

free functional fluids should be high, as in fluids used in parking-brakes or the like, where it is desired that the frictional level be high enough (at least 0125 so that the force generates a frictional torque level sufiicient to overcome the gravitational pull on a 30 incline. A class of additives which when added, in amounts of from about 0.1% to about 10%, preferably from about 0.5% to 5% by weight, to functional fluids of this invention, increase their static coelficient of friction to at least 0.125;; are oil-soluble alkali metal or alkaline earth metal organic sulfonates. Materials for making oil-soluble sulfonates include various petroleum fractions such as mineral lubricating oil fractions, alkyl-substituted aromatic compounds such as alkylated benzene or naphthalene and alkyl substituted polar-containing aromatic compounds such as alkylated phenol, naphthol, aniline, etc. Specific sulfonates which are particularly suitable for increasing the static coeificient of friction of functional fluids of this invention oil-soluble sodium, potassium, calcium and barium petroleum sulfonate, tetra-tertiarybutylnaphthalene sulfonate, dinonyl naphthalene sulfonate, diwaxnaphthalene sulfonate, diwaxbenzene sulfonate, stearylbenzene sulfonate, tertiary-octylphenol sulfonate, waxphenol sulfonate and mixtures thereof. Preferred are the oil-soluble sodium, calcium and/or barium petroleum sulfonate and dinonylnaphthalene sulfonate.

In addition to the two essential additives present in compositions of this invention, as well as the frictional additive (sulfonate), it is preferred to incorporate into such compositions a small amount (0.1-5%) of specific anti-oxidants from groups (a) an oil-soluble organic thiophosphate salt of the metals of group II of the periodic tablehaving an atomic number of from 12 to 56 or (b) a mixture in about equal proportions of an alkyl phenol and an arylamine. The anti-oxidant of group (a) include the group H metal salts of alkyl, aryl, alkaryl, or cycloalkyl monoand di-acid thio or dithio-phosphoric acids such as calcium, barium or zinc alkyl, cyclo alkyl or aryl mono and dithiophosphates. Preferred compounds are calcium, barium and zinc methylphenyl dithiophosphate, dimethyl cyclohexyl dithiophosphate, dihexyl dithiophosphate, lauryl benzyl dithiophosphate and mixtures thereof. Compounds of this type are available commercially under the trade names of Lubri-Zol 66, 304, 360 or 1060 (Lubri-Zol Corp.); Aerolube 70 (American Cyanamid Co.) and Stan-Add 71 (Standard Oil Co. of Indiana). A particularly preferred class of such compounds includes the Zn and Ba salts of dimethylcyclohexyl dithiophosphate, Ba salt of P S polybutene reaction products and/ or P s -terpene (pinene) reaction products. Such products are commercially available from Lubri-Zol Corporation, Standard Oil Company of Indiana and Monsanto Chemical Company, respectively, under the above indicated trade names.

The anti-oxidant mixture of group (b) include alkyl phenols, e.g., di and tri alkylphenols, for instance 2,4-, 2,3-, 3,4-, 2,6- and 3,5-diamyl phenol, 2,4-dimethyl-6- tertbutyl phenol, 2,6-ditertbutyl-4-methyl phenol; and arylamines such as phenyl-a-naphthylamine, or phenyl-B- naphthylamine.

Also optional additives can be used in compositions of this invention such as anti-foaming agent e.g., silicone polymers (DC 200 fluids) ranging in viscosity in centistokes from 100 to 1000 at 25 C. or Silicone Type A fluid made by DowCorning Co. and described in US. Patents 2,563,588 and 2,662,055. These optional agents when used in compositions of this invention are employed in amounts of from 0.0001% to 10% and preferably between 0.l% and 5%.

The base oil is a hydrocarbon oil preferably of wide viscosity range and having a high viscosity index and a low pour point. These oils can range in viscosity from 40 l SUS at F. to SUS at 210 F., and include mineral spray oil, transformer oil as well as lubricating oils having SAE numbers of 10, 20, 30, etc. Oils of this type have the following properties:

SAE 10 mineral oil Viscosity, SUS, at 100 F Viscosity, SUS, at 210 F 45.2 Viscosity index 106, Flash, 9 F 395 Fire, F- 440 Pour point, F -35 Another suitable base oil is a refined, highly refined transformer oil (A) having the following properties:

Sp. gr., API 30.9 Color V 30 Viscosity, SUS, at 100 F 56.9 Flash, COC, F 290 Fire, COC, F 320 Pour point, F Below --70 Still another suitable base oil is a refined mineral oil (B) having the following properties:

Sp. Gr., API 31.2 Color, ASTM -1 Pour point ---30 Flash, F 270 Fire, F 295 Viscosity, SUS, at 100 F 48 Viscosity index 33 The following compositions are illustrative of the present invention.

Composition A Stearic acid percent wt 0.2

Example I additiv do 0.2 Calcium petroleum sulfonate do 5 Zinc dimethyl cyclohexyl dithiophosphate.... do 0.5 Dimethyl silicone polymer (1000 cs. at 25 C.) p.p.m- 5 Mineral oil (B) Balance Composition B Stearic acid percent Wt 0.2

Compositions of this invention eliminate noise, frictional vibrations and stick-slip sliding in various equip ment such as liquid cooled hydraulic brake systems in which the friction members were made of steel and resilient, or semi-metallic, or full sintered metallic friction materials. Evaluation was done in actual automobile tests wherein the noise created after accelerating and suddenly stopping the vehicle was rated, 10 being excellent, no noise or stick-slip and zero (0) being poor, severe noise and stick-slip.

With compositions A, B, C, and D the ratings were between 8 and 10. Mineral oils (A) and (B), each containing 0.2% stearic acid, or 0.2% cerotic acid gave ratings of 4 and 5 respectively, whilethe same oils each containing 0.2% stearic acid and 5% Lubri-Zol66 gave ratings of 5. Transformer oil (A) or mineral oils (B) each containing 0.5% of n-octyl acid phosphate, dioctyl phosphate and triisooctyl phosphate gave ratingsof 4, 1 and 1, respectively, while transformer oil (A) containing 0.4% lauryl acid phosphate gave a rating of 3 and transformer oil (A) containing 0.2% lauryl acid phosphate and 2.5% Lubri-Zol 1060 gave a rating of 1.

The static coetficient of friction of Compositions B, C and D was about 0.04 whereas the static coefficient of friction of Composition A containing 2.5% neutral calcium petroleum sulfonate increased the coefficient of friction to 0.130 The addition of 2.5% of neutral calcium dinonylnaphthalene sulfonate or barium dinonylnaphthalene sulfonate, or neutral calcium petroleum sulfonate to Composition C increased the static coefiicient of friction of the compositions from 0.0411. to 15211., 1.88 1 and 1.42,, respectively. These values are far above the required minimum of 0.125 1. On the other hand, the addition of 2.5% of calcium naphthenate, or calcium C1448 alkyl salicylate, or zinc dimethylcyclohexyl dithiophosphate or tricresyl phosphate to Composition C gave static coeflicient of friction values of 0.086 0.49 0052 1 and 0.091 respectively. These values are below the required minimum of 0.125

Thus the data shows the outstanding properties which compositions of this invention possess with respect to eliminating noise and stick-slip in brake systems. On the other hand, mineral oils containing a fatty acid, e.g., stearic or cerotic acids alone or in combination thiophosphates or mineral oils containing various acid phosphates alone or in combination with a metal thiophosphate gave poor results. Also the data shows that the static coeflicient friction of compositions of the present invention can be increased to a desired value by addition to such compositions certain oil-soluble sulfonates and that other metal salts e.g. naphthenates or salicylates or phosphate esters are not effective when used for this purpose in compositions of this invention.

We claim as our invention:

1. A noise-free power transmission fluid consisting essentially of a major amount of a refined mineral lubricating oil and from about 0.05% to about 2% each of an aliphatic monocarboxylic acid having from 18 to 26 carbon atoms in the molecule and a reaction product prepared by reacting from 1 to 5 moles of an aliphatic amine having from 8 to 18 carbon atoms with a mol of an aliphatic acid pyrophosphate having from 8 to 18 carbon atoms until the reaction is substantially completed, the reaction being carried out at a temperature below that at which substantial decomposition of the reaction product occurs.

2. A noise-free power transmission fluid consisting essentially of a major amount of a refined mineral lubrieating oil and from about 0.05% to about 2% each of a saturated fatty acid having from 18 to 26 carbon atoms in the molecule and a reaction product prepared by reacting from 1 to 5 moles of a C aliphatic amine with a mol of an aliphatic acid pyrophosphate having from 8 to 18 carbon atoms until the reaction is substantially completed, the reaction being carried out at a temperature below that at which substantial decomposition of the reaction product occurs.

3. A noise-free power transmission fluid consisting essentially of a major amount of a refined mineral lubricating oil and from 0.05 to about 2% each of a saturated fatty acid having from 18 to 26 carbon atoms in the molecule and a reaction product prepared by reacting from 1 to 5 moles of a C alkyl amine with a mol of an alkyl acid pyrophosphate having from 8 to 18 carbon atoms until the reaction is substantially completed, the reaction being carried out at a temperature below that at which substantial decomposition of the reaction product occurs.

4. A noise-free power transmission fluid consisting essentially of a major amount of'a refined mineral lubricating oil and from about,0.05% to about 2% each of stearic acid and a reaction product of a C aliphatic amine with 21 mol of an alkyl pyrophosphate having from 8 to 18 carbon atoms until the reaction is substantially cornpleted, the reaction being carried out at a temperature below that at which substantial decomposition of the reaction product occurs, '5. A noise-free power transmission fluid consisting essentially of a major amount of a refined mineral lubricating oil and from about 0.05% to about 2% each of stearic acid and a reaction product prepared by reacting from 1 to 5 moles of a C aliphatic amine with a mol of octyl pyrophosphate until the reaction is substantially completed, the reaction being carried out at a temperature below that at which substantial decomposition of the reaction product occurs.

6. A noise-free power transmission fluid consisting essentially of a major amount of a refined mineral lubricating oil and from about 0.05 to 2% each of stearic acid and a reaction product prepared by reacting from Ito 5 moles of a C aliphatic amine with a mol of dioctyl pyrophosphate until the reaction is substantially completed, the reaction being carried out at a temperature below that at which substantial decomposition of the reaction product occurs.

7. A noise-free power transmission fluid consisting essentially of a major amount of a refined mineral lubricating oil and from about 0.05 to 2% each of cerotic acid and a reaction product prepared by reacting from 1 to 5 moles of a C aliphatic amine with a mo] of an alkyl pyrophosphate having from 8 to 18 carbon atoms until the reaction is substantially completed, the reaction being carried out at a temperature below that at which substantial decomposition of the reaction product occurs.

8. The power transmission fluid of claim 1 containing from about 0.1% to about 10% of an oil-soluble metal organic sulfonate the metal portion of the salt being selected from the group consisting of alkali and alkaline earth metals.

9. The power transmission fluid of claim 4 containing from about 0.1% to 10% of oil-soluble calcium petroleum sulfonate and from about 0.1 to about 5% of oil-soluble zinc cycloalkyl dithiophosphate.

10. The power transmission fluid of claim 5 containing from about 0.1% to 10% of oil-soluble sodium petroleum sulfonate.

11. A noise-free power transmission fluid consisting essentially of about 0.2% stearic acid, about 0.2% of a reaction product prepared by reacting from 1 to 5 moles of C C aliphatic amine with a mol of dioctyl pyrophosphate until the reaction is substantially completed, the reaction being carried out at a temperature below that at which substantial decomposition of the reaction product occurs, and about 0.1-0.5% of a mixture of an alkyl phenol and an aryl amine and the balance being a refined transformer mineral oil.

12. A noise-free power transmission fluid consisting essentially of about 0.2% stearic acid, about 0.2% of a reaction product prepared by reacting from 1 to 5 moles of C1648 aliphatic amine with a mol of dioctyl pyrophosphate until the reaction is substantially completed,

aliphatic amine with a mol of dioctyl pyrophosphate until the reaction is substantially completed, the reaction being carried out at a temperature below that at which substantial decomposition of the reaction product occurs, about 7 2.5-5% calcium petroleum sulfonate, about 0.5% zinc dimethylcyelohexyl di thiophosphate, and about 5 p.p.m. dimethyl silicone polymer and the balance being a refined transformer mineral oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,005,619 Graves June 18, 1 935 8 Benniug May 11, 1937 Baker Aug. 24, 1948 Watson May 30, 1950 Rudel Apr. 29, 1952 Woodstock et a1. Dec. 29, 1953 Watson Aug. 17, 1954 Jones Nov. 9, 1954 Wasson et a1. Apr. 15, 1958 Chenicek Aug. 19, 1958

Claims (1)

1. A NOISE-FREE POWER TRANSMISSION FLUID CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF A REFINED MINERAL LUBRICATING OIL FROM ABOUT 0.05% TO ABOUT 2% OF EACH OF AN ALIPHATIC MONOCARBOXYLIC ACID HAVINNG FROM 18 TO 26 CARBON ATOMS IN THE MOLECULE AND A REACTION PRODUCT PREPARED BY REACING FROM 1 TO 5 MOLES OF AN ALIPHATIC AMINE HAVING FROM 8 TO 18 CARBON ATOMS WITH A MOL OF AN ALIPHATIC ACID PYROPHOSPHATE HAVING FROM 8 TO 18 CARBON ATOMS UNTIL THE REACTION IS SUBSTANTIALLY COMPLETED, THE REACTION BEING CARRIED OUT AT A TEMPERATURE BELOW THAT AT WHICH SUBSTANTIAL DECOMPOSITION OF THE REACTION PRODUCT OCCURS.