BE490617A - - Google Patents

Description

       

   <Desc / Clms Page number 1>
 



  "Improvements relating to liquid compositions and methods of power transmission and lubrication using these
 EMI1.1
 no \. 0 compositions "., II \) 1-, .. -
The present invention relates to a liquid composition which can be used particularly for the transmission of power in hydraulic systems, and in particular as a non-flammable hydraulic liquid in hydraulic control systems on board aircraft; The subject of the invention is also a process for transmitting power in the parts of a hydraulic system, and for lubricating said parts.

 <Desc / Clms Page number 2>

 



   The present invention provides a composition consisting essentially of monoalkyl-diaryl phosphate, wherein the aryl groups are members of the group consisting of phenyl, cresyl and xylyl radicals and wherein the monoalkyl group has from 1 to 10 carbon atoms. , and in an amount sufficient of a polyalkyl methacrylate to increase the viscosity of the composition at elevated temperatures and to increase the viscosity index of the composition.



   Various fluids are known which are intended for the transmission of power in hydraulic devices, including certain known fluids for use in hydraulic systems of aircraft. However, aircraft hydraulic control systems for controlling the various devices on board an aircraft impose severe conditions on the hydraulic fluid used. Not only is the hydraulic fluid for airplanes subjected to operational and working conditions, but in addition, such a fluid must be as non-flammable as possible and must be sufficiently non-flammable to meet the specifications of the aeronautics industry, regarding fire resistance.

   The viscosity characteristics of the fluid should be such that it can be used within wide temperature limits; that is, it must offer sufficiently high viscosity at high temperature, low viscosity at low temperature, and low rate of change of viscosity as a function of temperature. Its freezing point must be low. Its volatility should be low at high operating temperatures and the volatility should be balanced, that is, there should be no evaporation or selective volatilization of any important constituent. it is, at high operating temperatures.

   It must have sufficient lubricity and mechanical stability to allow its use in pumps,

 <Desc / Clms Page number 3>

 valves, etc., self-lubricating, entering into the hydraulic systems of aircraft, and whose action on the fluid is very rigorous. It must be chemically stable in order to be able to withstand chemical reactions such as oxidation, decomposition, etc., so as to resist, under service conditions, the loss of the desired characteristics, which would be due to significant and sudden changes in pressure, temperature ß at high shear forces, and in contact with various metals which may be, for example, aluminum, bronze, steel, etc. It must not nor damage the seals or gaskets of the hydraulic system.

   It must not alter the materials of which this system is made and, in the event of a leak, it must not attack the various parts of the airplane with which it could accidentally come into contact. It must not be toxic or harmful to personnel likely to come into contact with it. Finally and in addition to all the requirements of this kind relating to its use on board airplanes, the fluid must be sufficiently non-flammable to meet the specifications of the aeronautical industry.



   Numerous mixtures have already been proposed for hydraulic fluids. The light fractions of petroleum oils with the addition of freezing point depressants, viscosity index improvers, inhibitors, etc., are among the best which have been proposed and these have received success. fairly widespread use as hydraulic fluids in airplanes. However, these substances are too easily flammable, their self-ignition temperature is low, they burn easily when ignited and have a high calorific value.

   These characteristics are particularly detrimental in the case of an airplane, where it is necessary to provide hydraulic lines in the immediate vicinity of electrical systems and motors, where a leak.

 <Desc / Clms Page number 4>

 high pressure hydraulic fluid, by a hard landing of the aircraft or rupture of the hydraulic system in flight, could cause a fire. None of these previously known materials meet the requirements to be met by an aircraft control fluid and are at the same time non-flammable enough to meet this condition, which is extremely important in the case of an aircraft.



   In many hydraulic systems power must be transmitted and the parts of the systems subject to friction lubricated with the hydraulic fluid used. The parts which are so lubricated include the friction surfaces of the source of motive force, which is usually a pump, valves, actuating pistons and cylinders, fluid motors and, sometimes, in the case of. machine tools, bearing tracks, tables and slides. The hydraulic system can be of either the constant volume or the variable volume type.



   The pumps can be of various types, including the piston pump, more particularly the piston pump with adjustable stroke, the variable displacement or variable displacement piston pump, the radial piston pump and the axial piston pump, pumps in which an articulated cylinder block is set at various angles relative to the piston assembly, for example the Vickers axial piston pump, or in which the piston control mechanism can be oriented at a variable angle relative to to the cylinder block; gear pumps which may be spur, helical or herringbone gears, or have variants of internally toothed crowns, or the Archimedes screw pump; finally the paddle pumps.

   The valves can be shut-off valves, reversing valves, pilot valves, throttle valves, consecutive acting valves, or pressure relief valves. Fluid motors are most often piston pumps, with constant or variable flow, set in rotation by the pressure of the hydraulic fluid of the system, thanks to the power supplied by the source of motive force controlling the pump.

 <Desc / Clms Page number 5>

 



  Such a hydraulic motor can be used with a variable flow pump to provide a variable speed transmission.



   Accordingly, said functions of transmitting power and lubricating the friction elements of such hydraulic systems must in practice meet many requirements depending on the nature of the particular hydraulic system and its particular application. Among these rigorous requirements which must be met by the method of transmitting power in the elements of such a system, and of lubricating these elements, it may be recalled that it must be carried out by means of a fluid having satisfactory properties. such as low viscosity at low operating temperatures, high viscosity at high operating temperatures, low degree of variation of viscosity as a function of temperature within operating temperature limits, particularly high viscosity index,

   lubricating properties, density, chemical stability, resistance to oxidation, resistance to emulsification, resistance to the formation of gums or deposits.



   Of particular importance are good lubricating properties. They include in particular the smoothness and strength of the film. Good lubricity and strength of the film reduces wear on the moving parts of pumps and valves, where the clearance between the friction surfaces can be so small that only microscopic films of lubricant are possible. The pressures exerted between certain moving parts can be very high. To avoid excessive wear and seizing, especially in the case of high fluid pressure, the hydraulic fluid must form a strong lubricating film that can withstand the pressure and the sweeping effect exerted between the moving parts, at operating temperatures.

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  The wear of the components of a hydraulic system causes internal leaks and an excessive release of heat by friction. The ability to withstand loads or lubricity is also important in some hydraulic systems. Wear to the hydraulic system gaskets and glands is harmful because it causes fluid to leak to the outside. Accordingly, it is desirable that the hydraulic fluid also lubricates the areas of contact with the seals.

   The situation with respect to hydraulic systems to which the present invention relates is generally known to those skilled in the art; it is generally described in the trade publication entitled "Hydraulic Systems Circulating Oils for Machine Tools (Machine Shop Series)" (1943), by Socony-Vacuum Oil Company, Inc., 26, Broad- way, New-York, NY; U.S. Patent No. 2,355,357, issued to HW Adams et al., issued August 8, 1944, describes a hydraulic system for airplanes, which also illustrates one type of hydraulic system to which the invention relates. "D.

   C.4 Maintenance Manual ", Volume III, Section 1, Hydraulics, and the" Douglas Service ", April 1947, pages 10 and 11, and February 1948, pages 10 and 11, all published by the Douglas Aircraft Company, Inc. , Santa Monica, California, also disclose hydraulic systems for airplanes, which illustrate the type of hydraulic system to which the invention relates. Similarly, the supercharger control system in the aircraft cabin DC-6, described in the "Douglas Service", February 1948, published by the Douglas Aircraft Company, Inc.



   The conditions imposed on the hydraulic system of an airplane are particularly severe. They include good lubricity to effectively lubricate the moving parts of the system, satisfactory viscosity at both the low and high temperatures at which the airplane may be called upon to operate, a low degree of variation in temperature. viscosity as a function of temperature, in particular a high viscosity index, good stability under conditions of use, avoiding per-

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 te the desired characteristics, as a result of large and sudden variations in pressure, temperature, high shear forces, the non-corrosion of metal parts which may be made of bronze, aluminum, steel, etc.,

   and the property of not damaging the joints or gaskets; and, in addition to all these conditions necessary in aviation, the fluid must also be very little flammable or very resistant to fire. The parts of the hydraulic system of an airplane must be as light as possible and this factor leads to placing new and rigorous demands on the lubricant and, in general, higher temperatures on the fluid.



   Among the particular friction surfaces that need to be lubricated are those made of hard steel on hard steel, especially ball bearings and gears, those of hard steel on cast iron, especially the sliding friction between the surfaces of this like, those made of hard steel on bronze or bronze alloys, for example between the steel piston and the bronze cylinder of a Vickers pump, as well as the metal surfaces in contact with gaskets made of elastic materials, in particular steel or bronze on neoprene, Buna N, butyl rubber, silastic rubber and natural rubber. Hard steel can be chrome plated.



   In accordance with this invention, it has been discovered that it is possible that hydraulic fluids remarkably satisfactory for hydraulic systems on board airplanes can be obtained by mixing a relatively small proportion of an alkyl methacrylate. resinous or suitable polymerized (polyalkyl methacrylate) with a higher proportion of a suitable monoalkyldiaryl phosphate;

   and a method has been discovered which enables the transmission of power in parts of such hydraulic systems and their lubrication by means of such compositions?
Monoalkyl-diaryl phosphates suitable for the purposes of this invention include especially those in which both

 <Desc / Clms Page number 8>

 aryl groups may be the same or different), the alkyl group being a saturated alkyl radical having from 1 to 10 carbon atoms, preferably from 4 to 8 carbon atoms, and preferably branched or iso-alkyl, and better still again, with a branched chain containing at least two side links.

   In addition, for some applications, especially at very low temperatures, preferred is a monoalkyl-diaryl phosphate which is either 1) a monoalkyl-diphenyl phosphate in which the alkyl radical is a saturated branched chain having from 1 to 8 carbon atoms, preferably with at least two side chains, in particular for the low viscosity at low temperatures, or 2) a monoalkyl-diaryl phosphate in which the alkyl radical is preferably branched chain having 1 to 10 carbon atoms, preferably with at least two side members in the chain, and in which the aryl radicals are phenyl, cresyl or xylyl, at least one of them being cresyl or xylyl, that is to say that at least one of the aryl radicals has at least one methyl substituent, and, preferably,

   a monoalkyl-dia- ryl phosphate in which the aryl radicals are cresyl or xylyl, i.e. each of the aryl radicals has at least one methyl substituent, particularly to prevent crystallization at extremely low temperatures . In addition, for the latter group, the alkyl group is preferably 1 to 6 carbon atoms for lower viscosity at low temperatures.



   Phosphates suitable for the purpose of this invention can be represented by the formula:
 EMI8.1
 

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 wherein R, can be phenyl, cresyl or xylyl; R2 can be phenyl, cresyl or xylyl, and R3 a saturated alkyl group having 1 to 10 carbon atoms, preferably 4 to 8 carbon atoms, and preferably branched or isoalkyl chain and, more preferably, wherein the branched chain has at least two branches or side chains. When R1 and R2 are both phenyl groups, it is preferable that R3 has from 1 to 8 carbon atoms for certain purposes, especially for use at extremely low temperatures, whether preferably branched chain and preferably having at least two side chains per main chain.

   In general, for applications at extremely low temperatures, the monoalkyl group is preferably a branched chain, saturated, preferably with at least two side chains, with at least one of the two aryl groups having at least one methyl substituent, ie. that is, R1 or R2 and preferably both should be cresyl or xylyl. In addition, mixtures of these phosphates can be used, especially as indicated in particular below.



   By way of example, such phosphates suitable for the purpose of the invention include the phosphates of: alkyl-diphenyl, alkyl-phenyl-cresyl, alkyl-dicresyl, alkyl-phenyl-xylyl, alkyl-dixyly-le, alkyl-cresyl -xylyl, in which the alkyl groups are represented as follows:
 EMI9.1
 C1 alkyl group:. methyl CH3- Group C2 alkyl: ethyl CH 3. CH2- C3 alkyl groups: normal propyl CH3.CHZ.CHZ-

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2.isopropyl (CH 3) 2. CH.- C4 alkyl groups:
1.normal butyl
 EMI10.1
 CH 3. (CH2) 2.CH2- 2.isobutyl (CH3) 2CH.CH2-
3. secondary butyl CH3. CH2.CCH3 4.tertiary butyl (CH3) 3.C- C5 alkyl groups: 1.normal amyl
 EMI10.2
 CH3.

   (CH2) 3CH2- 2.isoamy le (CH3) zCH.CHZ.CHZ- 3. 2-methyl-butyl
 EMI10.3
 GH3.CHZ.CH.GH2- - CH3 4.2.2-dimethyl-propyl
CH3 CH3. C.CH2CH3 5.1-methyl-butyl CH: 3 (CH2) 2. CH- CH3 6.diethyl-methyl
H CH3. CH2.CCH2 CH3
7. 1,2-dimethyl-propyl
 EMI10.4
 CH. CH. CH-
3CH3CH3 8.tertiary amyl
CH3
CH3. CH2.C- CH
3 2CH3

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 C6 alkyl groups: normal hexyl
 EMI11.1
 CH3. (CHZ) CH2- 2.1-methyl-amyl
 EMI11.2
 CH).

   (CH2)) CH- CH3
 EMI11.3
 3.1-Ethyl-butyl CH (CH 2) 2 CH-
C2H5 4. 1,2,2-trimethyl-propyl (CH3) 3C.CH- 3 3 @ CH3
 EMI11.4
 5.33-dimethyl-butyl (CH3) 3C.CH2.CH2 6.1.1,2-trimethyl-propyl
CH3
 EMI11.5
 (CH3) z.CH.C-
32 CH
3 7. 2-methyl-amyl
 EMI11.6
 CH) e (CH2) 2.CH.CH2-
CH3 8,1-dimethyl-butyl
CH3
 EMI11.7
 CH3 (CH2) 28-
CH3 9.l-ethyl-2-methyl-propyl
CH3
 EMI11.8
 CH CH. VS..



   3 C2H5 10. 1,3-dimethyl-butyl
 EMI11.9
 CH) .CH2 .CH2CH-
3CH3 2CH3 11.isohexyl
 EMI11.10
 (CH) '2CH. (CH2) 2CH2-12.3-methyl-amyl CH3.CH2.CH.CH2CH2- CH3

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 13. 1,2-dimethyl-butyl
CH3
 EMI12.1
 CH 3. CH2. CH. CH ...



   CH3 14. 1-methyl-1-ethyl-propyl
CH3
CH3CH2C-
 EMI12.2
 C2H5 15. 2-ethyl-butyl CH3CH2. CH. CH2-
CH2H5 C7 alkyl groups: 1.normal heptyl
CH3 (CH2) 5CH2- 2.1,1,2,2-tetramethyl-propyl
CH3CH3 CH3.C .CCH3CH3 3.12-dimethyl-1-ethyl-propyl CH3CH3 CH.CH.C- 3 C2H5 4.11,2-trimethyl-butyl
CH3 CH3
 EMI12.3
 CH .CH.CH .C-
CH3 5.1-isopropyl-2-methyl-propyl
CH3 CH.CH.CHCH (CH3) 2 6.l-methyl-2-ethyl-butyl
CH3
 EMI12.4
 CH 3 * CH 2 * CH.CH-
3 C2H5 7,1-diethyl-propyl
C2H5
CH3. CH2.C-
CH
3 C2H5

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 8. 2-methyl-hexyl
 EMI13.1
 CH3 (CH2) 3CH.CH2-
CH3 9,1-dimethyl-amyl
CH3
 EMI13.2
 CH3 (CH2) 3C¯
CH3 10. 1-isopropyl-butyl
 EMI13.3
 CH). CH2.

   CH2CH- CH (CH)) @CH (CH3) 2 11. 1-ethyl-3-methyl-butyl
CH3
 EMI13.4
 CH). CH. CH2. CH-
3 C2H5 12. 1,4-dimethyl-amyl
CH3
 EMI13.5
 CH3.CH.CH2.CH2.CH2
CH3 13: isoheptyl
 EMI13.6
 (CH3) 2CH (CH2) 3CH2- 14. 1-methyl-1-ethyl-butyl
CH3
 EMI13.7
 CH3.CH2.CH2.C- C2H5 15. 1-ethyl-2-methyl-butyl
CH3
 EMI13.8
 CH3.CH2.CH.CH-
C2H5 16.1-methyl-hexyl
 EMI13.9
 CH3 (CH2) CH¯
CH3 17.1-propyl-butyl
 EMI13.10
 CH3.CH2.CH2BH. 2.c3H7 37 C8 alkyl groups:
1.normal octyl
 EMI13.11
 CH3 (CHZ) 6CH2 2.1-methyl-heptyl
 EMI13.12
 CH) (CH2) 5CH- @
CH3

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 3.11-Diethyl-2-methyl-propyl CH3C2H5 CH3.

   CH.CC2H5
 EMI14.1
 4.11,3,3-tetraaethyl-butyl CH3 CH3
 EMI14.2
 CH .C.CH .C-
CH3 CH3 5.11-diethyl-butyl
C2H5
 EMI14.3
 CH) .CH2.CH2.C-
C2H5 6.11-dimethyl-hexyl
CH3
 EMI14.4
 CH) (CH2) 4C- CH 3 7. 1-methyl-1-ethyl-amyl
CH3 CH3 (CH2) 3CC2H5 8. 1-methyl-1-propyl-butyl
CH3
 EMI14.5
 CH) .CH2.CH2.C-
C3H7 9.2-ethyl-hexyl
 EMI14.6
 CH3 (CH 2) 3CH.CH 2-
C2H5 10. 6-methyl-heptyl (isooctyl)
 EMI14.7
 CH3.CH (CH2) CHZ-
CH3
C9 alkyl groups: 1.normal nonyl
 EMI14.8
 CH3 (CH2) CH- 2.1-methyl-octyl
 EMI14.9
 CH3 (CH2) 6CH-
CH3 3.1-ethyl-heptyl
 EMI14.10
 CH3 (CH2) 5CH- @
C2H5

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   4.11-dimethyl-heptyl
CH3
 EMI15.1
 CH3 (CH2) 5CCH3 5.1-ethyl 1-propyl-butyl
C3H7 CH3.

   CH2.CC3H7 6.1, 1-diethyl-3-methyl-butyl
CH3 C2H5
 EMI15.2
 CH .CH.CH .C- 3 @ C2H5 7.di-isobutyl-methyl
 EMI15.3
 (CH3) zCH.CHI z CH-. 3,5,5-trimethyl-hexyl (CH3) 3C.CHCH.CH2.CHZ-
CH3 9.3,5-dimethyl-heptyl
CH3
 EMI15.4
 CH3.CH2.CH.CH2CH.CH.CH2
CH3 C10 alkyl groups: 1.normal decyl
 EMI15.5
 CH) (CH2) gCH2- 2.1-propyl-heptyl
 EMI15.6
 CH) (CH2) 5CH-
C3H7 3.11-diethyl-hexyl
C2H5
 EMI15.7
 CH3 (CH2) C-
C2H5 4.11-dipropyl-butyl
C3H7
 EMI15.8
 CH) (CH2) 2C- c3H7 5. 2-isopropyl-5-methyl-hexyl
CH3
 EMI15.9
 CH3.CH (CH2) 2CH.CH - CH CH (CH3) 2

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As used herein, the term "cresyl" denotes the tolyl or methyl-phenyl radical and the term "xylyl" denotes the dimethylphenyl radical.

   The cresyl radicals can be ortho, meta or para radicals or mixtures thereof, but they are usually mixtures of meta and para to avoid the toxic effect of the ortho isomer. Any isomer of xyly-1 radicals or mixtures thereof can be employed.



   Polyalkyl methacrylates suitable for the purpose of this invention are generally those which result from the polymerization of alkyl methacrylates in which the alkyl groups can have from 4 to 12 carbon atoms. Alkyl groups can be mixtures such as those derived from a mixture of alcohols and in this case there may be some alkyl groups of up to two carbon atoms as a minimum and up to about 18 carbon atoms as a minimum. maximum. The number of carbon atoms in the alkyl group should be such that the polymer is compatible with the particular phosphate used. Usually, it will be found that the lower the alkyl group of the phosphate, the lower the alkyl group of the methacrylate. It will usually be advantageous for the alkyl group of the methacrylate monomer to be from about 8 to 10 carbon atoms.

   The alkyl group can be a branched chain or isoalkyl. The molecular size of the polymerized alkyl methacrylate should be sufficient to increase the viscosity of the monoalkyldiaryl phosphate to which it is added, and small enough to be compatible with it. In general, the average molecular weight will be between the limits of about 8,000 to 12,000. The polyalkyl methacrylate should be such and in sufficient proportion for the viscosity to be increased at high temperatures (such as 210 F., for example) and for the viscosity index to be preferably increased to at least 100 and more preferably more than 150.

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   In preparing the compositions of this invention, the alkyl polymer methacrylate can be added to the phosphate or the phosphate mixture, or the monomer can be polymerized in situ in the phosphate or the phosphate mixture by adding thereto. ester of unpolymerized alkyl methacrylate and then polymerizing the monomer to the desired degree.



   Polyalkyl methacrylates suitable for the purposes of this invention are made, sold and are available from the Rohm and Haas Company, Philadelphia, Pensylvania, under their trademark ACRYLOID and under the specific names, for example, of Acryloid HF-845, Acryloid HF-855, Acryloid HF-860. In these designations, the last two digits ie "45", "55" and "60" indicate the viscosity in "centistokes" of the polyalkyl methacrylate contained in the commercial product, viscosity measured in a solution. at 30% by weight in toluene at 100 F. or other standard base having a viscosity of 3.5 "centistokes" at 100 F. In general,

   these polymers have a molecular weight within the range of about 5,000 to 18,000. Usually the alkyl radicals of these polymerized alkyl methacrylates are C8 but they can be C8 - C10.



   Usually, a smaller proportion and, in particular, 0.8 to 10 percent by volume of the polyalkyl methacrylate (excluding any solvents) will be considered satisfactory, and this will preferably be a proportion in the limits are 1 to 5 percent. This percentage of polyalkyl methacrylate is based on the sum of the phosphate and the polymer being taken to be 100 percent.



   The invention is illustrated in more detail by the following examples: Example 1. A polyoctyl methacrylate having an average molecular weight of approximately 10,000 and which may vary from 5,000 to 18,000 approximately, in a solution of toluene, obtained. of the Rohm and Haas Company under its brand ACRYLOID HF-845, was stripped of the

 <Desc / Clms Page number 18>

 toluene solvent. Two percent of the obtained substantially pure polyoctyl methacrylate was mixed with and dissolved in 98 percent by volume of 2-ethyl-hexyl-diphenyl phosphate, obtained from Monsanto Chemical Company, under its trademark Santicizer 141. Santicizer 141 is described in Technical Bulle- tin OD-III of the Development Department, Organic Chemicals Division, Monsanto Chemical Company, St. Louis, Missouri.

   Polyoctyl methacrylate, minus the toluene solvent, was an excessively compact material, almost a solid, and dissolved in octyl-diphenyl phosphate in about two days, with intermittent stirring at 100 C. The results of the tests on the liquid obtained are given in Table I below.



  Example 2. A polyoctyl methacrylate having an average molecular weight of about 10,000 and varying from about 5,000 to 18,000, dissolved in 45 volume percent of a light petroleum oil having its flash point. at 200 F., obtained from the Rohm and Haas Company, under its trademark Acryloid HF-855, in a proportion of 5 percent by volume, was mixed with and dissolved in 95 percent by volume of 2-ethylhexyl phosphate -diphenyl (Santicizer 141). In this case, the light petroleum acted as a mutual solvent for the poly-octyl methacrylate and the octyl-diphenyl phosphate, and facilitated the manufacture of the desired liquid solution.

   Since only a small proportion (5 / percent) of the commercial Acryloid HF-855 was added to the octyl-diphenyl phosphate, the proportion of light petroleum oil was not high enough to give the product. final liquid product of any undesirable properties.



  Table I below shows the result of tests carried out on the liquid product obtained.

 <Desc / Clms Page number 19>

 
 EMI19.1
 



  T-A-B-L-E-A-U - Ie
 EMI19.2
 
<tb> Phosphate <SEP> of <SEP> Fluid <SEP> of <SEP> Fluid <SEP> of
<tb>
<tb>
<tb>
<tb> 2-ethyl-he- <SEP> example <SEP> example
<tb>
<tb>
<tb>
<tb> xyl-dipheny- <SEP> 1.2.
<tb>
<tb>
<tb> the
<tb>
<tb>
<tb>
<tb>
<tb> Specific <SEP> weight
<tb>
<tb>
<tb>
<tb> 60/60 <SEP> 1.09 <SEP> 1.03 <SEP> 1.076
<tb>
<tb>
<tb>
<tb> Point <SEP> of <SEP> frozen
<tb>
<tb>
<tb> tion <SEP> Inf. to <SEP> -60 F <SEP> -60 F. <SEP> -60 F.
<tb>
<tb>
<tb>
<tb>



  Index <SEP> of <SEP> neutra-
<tb>
<tb>
<tb>
<tb> lisation <SEP> (mg <SEP> KOH /
<tb>
<tb>
<tb>
<tb> gram) <SEP> 0.16
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Viscosity <SEP> (centistokes)
<tb>
<tb>
<tb>
<tb> -30 F <SEP> 2.167 <SEP> 2.440 <SEP> 2.290
<tb>
<tb>
<tb>
<tb> 100 <SEP> 10.1 <SEP> 13.4 <SEP> 14, <SEP> 6 <SEP>
<tb>
<tb>
<tb>
<tb> 210 <SEP> 2.46 <SEP> 3.37 <SEP> 3.71
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Viscosity <SEP> index <SEP>
<tb>
<tb>
<tb>
<tb> (A.S'.T.M.) <SEP> 65 <SEP> 143 <SEP> 163
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Flammability:
<tb>
<tb>
<tb>
<tb> Auto <SEP> temperature
<tb>
 
 EMI19.3
 ignition 1.060 1.050 (A.S.T.M. 2 $ 6-30) 1.050 F.
 EMI19.4
 
<tb> Test <SEP> by <SEP> projection <SEP> None <SEP> intensive <SEP> Decrease
<tb> sification <SEP> of <SEP> of <SEP> fire
<tb> fire.
<tb>
<tb>



  Ignition test <SEP> <SEP> to <SEP> Ignited <SEP> Ignited <SEP> with.
<tb> high <SEP> temperature <SEP> with <SEP> a lot <SEP> a lot <SEP> of
<tb> of <SEP> difficulty.difficulty.
<tb>
<tb>



  Multiple <SEP> test
<tb> Combustion <SEP> on <SEP> tube <SEP> None <SEP> None
<tb> "<SEP> at <SEP> bottom <SEP> of <SEP> the screen <SEP> Do <SEP> burn <SEP> not <SEP> Do <SEP> burn <SEP> not
<tb>
 
The "flammability" tests were carried out in accordance with the following standards: F-3-b spray flammability test, F-3-c high temperature flammability test, and multiple F-3 flammability tests -d set forth on pages 4 and 5 of the Proposed Specification for Non-flammable Type Hydraulic Fluid, July 21, 1947, of the Aircraft Industries Association of America, Inc., currently SAE Specification AMS 3150, published May 1, 1948.

   The fluids which are the subject of this invention satisfactorily meet all of the non-flammability conditions of the specification of the Aircraft Industries Association of America, Inc.

 <Desc / Clms Page number 20>

 



   Since certain parts of the hydraulic systems used in airplanes, such as the seals and the diaphragm of the accumulator, are made of rubber or any synthetic elastic material, the swelling effect of the hydraulic fluid used on said rubber or other matter, elasticity is important. Most hydraulic fluids of the non-flammable type proposed swell all of these elastic materials by about 20 percent and more, which is too large to be satisfactory. It was found that the fluid of Example 2, however, only swelled butyl rubber, one of the synthetic elastic materials of which the seals and diaphragm can be made, by 4.7 percent.

   Therefore, with the fluid object of this invention, it is possible to select a suitable elastic material, which will not exaggerately swell when used with the hydraulic fluid.



   To more fully illustrate the utility of this invention and the surprising results obtained with the compositions of this invention, the fluid of Example 2 was subjected to severe test conditions in a specially constructed hydraulic system. to be practically identical to the hydraulic control system of an airplane, with the exception only of the servo-organs and the length of the hydraulic lines, these tests being carried out under extreme conditions of temperature and pressure and under high pumping rate, as is the case under take-off conditions, requiring high hydraulic system power and high operating temperature, of 160 F. This test system includes all functional parts as used in an airplane,

   under extreme practical operating conditions. This system is shown in sketch 4 of the AIA Proposed Specification for Non-Flammable Type hydraulic Fluid, July 21, 1947, referred to above.



   Ten gallons of the fluid from Example 2 were placed in

 <Desc / Clms Page number 21>

 The system tank and system was subjected to stable operating conditions, a relief pressure of 3,000 pounds per square inch and an operating temperature of 160 F. This fluid exhibited excellent stability and stability. served for the extraordinary 450 hours (bie above 25,000 system revolutions and equivalent to approximately 4,500 flight hours). No difficulty arose during this extremely long period of operation and the test was discontinued, not because of any failure but simply because the excellence of the fluid was amply demonstrated.



  During this test, the following readings were taken with the results shown in Table II below: T A B L E A U II
 EMI21.1
 
<tb> Hours <SEP> of <SEP> Index <SEP> of <SEP> Viscosity <SEP> at <SEP> 100 F
<tb> Operation <SEP> Neutralization <SEP> in <SEP> centistokes
<tb>
<tb> 0 <SEP> 0.16 <SEP> 14.4
<tb> 5 <SEP> 0.17 <SEP> 13.2
<tb> 7 <SEP> 0.16 <SEP> 12.8
<tb> 16 <SEP> 0.17 <SEP> 12.7
<tb> 25 <SEP> 0.15 <SEP> 12.5
<tb> 42 <SEP> 0.16 <SEP> 12.4
<tb> 58 <SEP> 0.19 <SEP> 12.3
<tb> 74 <SEP> 0.15 <SEP> 12.3
<tb> 90 <SEP> 0.17 <SEP> 12.2
<tb> 140 <SEP> 0.15 <SEP> 12.0
<tb> 164 <SEP> 0.18 <SEP> 12.1
<tb> 243 <SEP> 0.15 <SEP> 11.9
<tb> 323 <SEP> 0.22 <SEP> Il, 8
<tb> 398 <SEP> 0.27 <SEP> 11.9
<tb> 450 <SEP> End <SEP> of test <SEP> 0.35 <SEP> 11,

  7
<tb>
 
The composition which is the subject of the invention has an extremely low coefficient of friction and a high resistance in the film state, so that its lubricity is extremely high, which makes it eminently suitable for lubricating the moving parts of hydraulic systems. intended for rigorous service. While a Vickers pump is usually useless after 200 hours of operation, with ordinary hydraulic fluids, in this system no measurable wear is seen after 200 hours of operation. help

 <Desc / Clms Page number 22>

 of the fluid of Example 2. Furthermore, after the test was stopped after 450 hours, the Vickers pump appeared to be in excellent condition.

   The extremely low wear value of the Vickers pump components is highlighted by the following table: T A B L E A U III
 EMI22.1
 
<tb> Parts <SEP> of <SEP> the <SEP> pump <SEP> Vickers <SEP> Weight <SEP> in <SEP> grams
<tb> Number <SEP> Designation <SEP> Before <SEP> test <SEP> After <SEP> 450 <SEP> hours
<tb>
<tb> 83.279 <SEP> Plate <SEP> of <SEP> valve <SEP> 352.5 <SEP> 551.8
<tb> 83.278 <SEP> Block <SEP> cylinder <SEP>. <SEP> 184,429 <SEP> 184,220
<tb> 79. <SEP> 063 <SEP> Ball joint <SEP> of <SEP> stop <SEP> 5,705 <SEP> 5,703
<tb> 59.561 <SEP> Small <SEP> ball joint <SEP> of <SEP> stop <SEP> 2,670 <SEP> 2,630
<tb>
 Example 3.



  95% by vol. 6-methyl-heptyl-diphenyl phosphate
 EMI22.2
 
<tb> 5% <SEP> in <SEP> vol. <SEP> Acryloid <SEP> HF-855
<tb>
<tb> Point <SEP> of <SEP> freezing <SEP> inf. <SEP> to <SEP> -90 F.
<tb>
<tb> Viscosity <SEP> at <SEP> 210 F. <SEP> 3.8 <SEP> centistokes
<tb> 100 <SEP> 15.2 <SEP> "
<tb> -30 <SEP> 2.100 <SEP> "<SEP>
<tb>
<tb> <SEP> index of <SEP> neutralization <SEP> 0.28
<tb>
 
 EMI22.3
 Auto-ignition temperature (ASTHI) 1.050 F.



   Although the fluids of Examples 1, 2 and 3 above behave remarkably, especially as hydraulic fluids in aviation, their use at extremely low temperatures, especially in hydraulic systems in which the pump is not operating or in which the fluid remains static or at rest for certain periods of time at extremely low temperatures, may nevertheless be somewhat restricted by a tendency to solidify or crystallize in vessels of certain definite shapes due, it seems , supercooling.

   This phenomenon was manifested in particular with regard to the fluid of Example 2, when an accumulator similar to that of the hydraulic test device mentioned above, and containing the fluid, was subjected to the temperature of -30 F. for three days, the fluid remaining there immobile and subjected to a pressure of about 50 free per pou-

 <Desc / Clms Page number 23>

 this square.



   However, it was subsequently found that compositions according to the invention can be produced which are not only highly satisfactory as hydraulic fluids in aviation, as is the case with the fluids of Examples 1. , 2 and 3 above, but which, moreover, do not crystallize at extremely low temperatures or exhibit this phenomenon at much lower temperatures. Another significant feature of the invention is that it can be achieved by the use of particular monoalkyl-diaryl phosphate mixtures selected from the group described in the foregoing disclosure.



   The mixtures of monoalkyl-diaryl phosphates referred to above can be obtained by mixing two or more particular monoalkyl-dia- ryl phosphates, such as, for example, a mixture of isooctyl-diphenyl phosphate and a phosphate d. isohexyl-diphenyl or two isomeric octyl-diphenyl phosphates. Such a mixture of monoalkyl-diaryl phosphates can also be obtained by producing the monoalkyl-diaryl phosphate with a mixture of alcohols, in particular a mixture of alkyl alcohols, to provide the compounds. alkyl groups, resulting in a mixture of monoalkyl-diphenyl phosphates, for example, with differing alkyl groups.

   Such mixtures from alcohols can be derived, for example, from compounds which are themselves derived from petroleum, such as, for example, from an olefin fraction obtained from petroleum converted into a mixture of alcohols by reaction with. carbon monoxide and hydrogen, according to the Oxo process (See, for example, "Alcohols above C3 Produced from
Olefins, CO and Hydrogen ", Chemical Industries, February 1947, pp. 232-233). Such a hydrocarbon fraction of olefins may contain, for example, a range of olefins from

 <Desc / Clms Page number 24>

 C3 to C7, which when converted to alcohols by the Oxo process results in a mixture of C4 to C8 alcohols, comprising isomeric forms of the same number of carbon atoms.

   Such an olefin fraction can also be, for example, essentially isomers of C7 olefins which, when converted to alcohols by the Oxo process, results in a mixture of isomers of C8 alcohols. . When such alcohol mixtures are used to produce alkyl diphenyl phosphate, for example, a corresponding mixture of C8 alkyl diphenyl phosphates is obtained. Any similar mixture of alkyl groups can be used, and in particular comprising a mixture of C, C and C6, C6, C6 and C7, C7, C7 and C8, C8, C8 and C9 or more extended series.



   The following examples illustrate such mixtures produced in accordance with the invention: Example 4.
 EMI24.1
 



  95% by volume of mixture of 50o by volume of 2-ethyl-hexyl-diphenyl phosphate 50 by volume of 6-methyl-heptyl-diphenyl phosphate 5% by volume of ACRYLOID HF- $ 55 Viscosity at 210 F ... .................. 3.85 centistokes
100 ..................... 15.0 centistoikes -30 ..................... 2.256 centist & kes
 EMI24.2
 
<tb> Viscosity <SEP> <SEP> index <SEP> 165
<tb>
<tb> Point <SEP> of <SEP> freezing <SEP> -70 F.
<tb>
<tb>



  Specific <SEP> weight <SEP> (60/60) <SEP> 1.079
<tb>
<tb> Auto-ignition temperature <SEP> <SEP> (ASTM) <SEP> 1.050 F.
<tb>
 



   Crystallization while keeping at low temperature No crystallization at -40 F.



   The phenomenon of crystallization observed for the fluid. of Example 2 above, using 2-ethylhexyl-diphenyl phosphate, was also observed for
Substantially pure 6-methyl-heptyl (isooctyl) diphenyl when

 <Desc / Clms Page number 25>

 was used without the addition of 2-ethyl-hexyl-diphenyl phosphate but when mixed as in Example 4 it was surprisingly noted that no similar crystallization occurred at -40 F.



   Further examples will be found below, giving different proportions for the two alkyl diphenyl phosphates: Example 5:
 EMI25.1
 95% by volume of mixture 70 by volume of 2-ethyl-hexyl-diphenyl phosphate 30% by volume of 6-methyl-heptyl-dipheryl phosphate 5% by volume of Acryloid HF-855 Freezing point less than - 60 F.



  Example 6:
 EMI25.2
 95% by volume mixture of 30 by volume 2-ethylheptyl-diphenyl phosphate) 70% by volume 6-methyl-heptyl-diphenyl phosphate 5% by volume Acryloid HF-855 Freezing point below -60 F.



   The following are examples of the use of a mixture of alkyl-diphenyl phosphates, the alkyl groups of which are derived from a mixture of alcohols obtained from a converted olefin fraction. into alcohols by the Oxo process.



  Example 7: 95% by volume of mixed Cg-alkyl-diphenyl phosphate 5% by volume of Acryloid HF-855.



  Freezing point . -70 F.



   This composition showed no tendency to crystallize, as did the fluid of Example 2 at temperatures as low as -40 F.

 <Desc / Clms Page number 26>

 



   The mixed C8 alkyl of this alkyl diphenyl phosphate was derived from a mixture of alcohols obtained from an olefin fraction obtained from petroleum, predominantly C7 but containing C6 and C8, which were converted to the corresponding alcohols by the Oxo process to produce a mixture of alcohols predominantly Cg but containing C7 and C9.

   The particular alkyl groups of this mixture of alkyl-diphenyl phosphates were about 55-65% isooctyl (6-methyl-heptyl) and about 5-10% C9 alkyl groups, the remainder predominantly. of other C8 isomers and a small amount of C8 isomers
 EMI26.1
 c7 "This mixed C8-alkyl-diphenyl phosphate had the following properties:
 EMI26.2
 
<tb> Viscosity <SEP> at <SEP> 210 F. <SEP> 2.69 <SEP> centistokes
<tb>
<tb> 100 <SEP> 11.2 <SEP> centistokes
<tb>
<tb> 0 <SEP> 337 <SEP> centistokes
<tb>
<tb> -40 <SEP> 7.988 <SEP> centistokes
<tb>
<tb> Freezing <SEP> point <SEP> <SEP> lower <SEP> than <SEP> -65 F.
<tb>
 



   The fluid of this example, besides being highly satisfactory as a hydraulic fluid for airplanes, has the property of not crystallizing at extremely low temperatures, due to the mixture of phosphates.



  Example 8:
 EMI26.3
 95% by volume of mixture of 50% of 2-ethyl-hexyl-diphenyl phosphate 50 of Cg-alkyl-di-phenyl phosphate mixed
 EMI26.4
 
<tb> 5% <SEP> in <SEP> volume <SEP> of Acryloid <SEP> HF-855
<tb>
<tb> Viscosity <SEP> at <SEP> 210 F. <SEP> 3.98 <SEP> centistokes
<tb>
<tb> 100 <SEP> 15.7 <SEP> centistokes
<tb>
<tb> -30 <SEP> 2.668 <SEP> centistokes
<tb>
<tb> <SEP> index of <SEP> neutralization <SEP> 0.25
<tb>
<tb> Point <SEP> of <SEP> freezing <SEP> -70 F.
<tb>
 

 <Desc / Clms Page number 27>

 
 EMI27.1
 
<tb>



  Specific <SEP> weight <SEP> (60/60) <SEP> 1,000
<tb>
<tb> Auto-ignition temperature <SEP> <SEP> (ASTM) <SEP> 1.040 F.
<tb>
 



   This fluid showed no tendency to crystallize at -40 F.



   The mixed C8-alkyl-diphenyl phosphate was the same as used in Example 7 above.



   The fluid was used as a hydraulic fluid and lubricant for the control mechanism of the supercharger of a DC-6 aircraft's tine for more than 650 flight hours. One such cabin supercharger system is described in the "Douglas Service", February 1948, published by the Douglas Aircraft Company, Inc., Santa Monica, California. Ordinary fluids used in such a system require renewal at a maximum of about 200 flight hours and are of a much higher viscosity, with the inherent difficulties of operating at low temperatures. which are avoided by the fluids of this invention.



  Example 9: 95% by volume of mixed isomer nonyl-diphenyl phosphate 5% by volume of Acryloid HF-855.



   The resulting mixture was tested and found to have the following properties:
 EMI27.2
 
<tb> Point <SEP> of <SEP> freezing <SEP> -50 F.
<tb>
<tb>



  Viscosity <SEP> to <SEP> 210 F. <SEP> 4.65 <SEP> centistokes
<tb>
<tb>
<tb> 100 <SEP> 19.3 <SEP> centistokes
<tb>
<tb>
<tb> - <SEP> 30 <SEP> 5. <SEP> 100 <SEP> centistokes
<tb>
<tb>
<tb> <SEP> index of <SEP> viscosity <SEP> 174
<tb>
 Auto-ignition temperature 1.040 F.



   This fluid showed no tendency to crystallize at temperatures as low as -50 F.

 <Desc / Clms Page number 28>

 



   The mixed isomeric nonyl-diphenyl phosphate was a mixture of alkyl-diphenyl phosphates of which the alkyl groups were 90% 3,5,5-trimethyl-hexyl and 10% 3,5-dim-methyl. -heptyle.



   Examples of other similar mixtures are given below: Example 10:
 EMI28.1
 95% by volume of mixture of 70 by volume of 2-ethylhexyl-diphenyl phosphate 30 by volume of mixed isomer nonl-diphenyl phosphate
 EMI28.2
 
<tb> 5% <SEP> in <SEP> volume <SEP> of Acryloid <SEP> HF-Ô55
<tb>
<tb> Point <SEP> of <SEP> freezing <SEP> lower <SEP> to <SEP> - <SEP> 60 F.
<tb>
<tb>



  Viscosity <SEP> to <SEP> 210 F. <SEP> 4.06 <SEP> centistokes
<tb>
<tb> 100 <SEP> 16.1 <SEP> centistokes
<tb>
<tb> <SEP> index of <SEP> viscosity <SEP> 177
<tb>
 
The fluid from this example did not crystallize at -30 F., as the fluid from Example 2 did, but did crystallize at -40 F. under analogous conditions, indicating that the temperature at which such crystallization occurs, had been lowered.



  Example 11:
 EMI28.3
 95% by volume mixture of / 50% by volume 2-ethyl-hexyl-diphenyl phosphate 50% by volume isomeric non-nyl-diphenyl phosphate mixed.
 EMI28.4
 
<tb>



  5% <SEP> in <SEP> volume <SEP> of Acryloid <SEP> HF-855
<tb>
<tb> Point <SEP> of <SEP> freezing <SEP> lower <SEP> than <SEP> -60 F.
<tb>
<tb>



  Viscosity <SEP> to <SEP> 210 F. <SEP> 4.16 <SEP> centistokes
<tb>
<tb> 100 <SEP> 16.7 <SEP> centistokes
<tb>
<tb> Viscosity <SEP> <SEP> index <SEP> 175
<tb>
 

 <Desc / Clms Page number 29>

 Example 12:
 EMI29.1
 95% by volume of mixture of 30% by volume of 2-ethyl-hexyl-diphenyl phosphate 70d / o by volume of mixed isomer nonyl-diphenyl phosphate.
 EMI29.2
 
<tb>



  5% <SEP> in <SEP> volume <SEP> of Acryloid <SEP> HF-Ô55
<tb>
<tb> Point <SEP> of <SEP> freezing <SEP> lower <SEP> to <SEP> - <SEP> 60 F.
<tb>
<tb>



  Viscosity <SEP> to <SEP> 210 F. <SEP> 4.46 <SEP> centistokes
<tb>
<tb> 100 <SEP> 18.1 <SEP> centistokes
<tb>
<tb> <SEP> index of <SEP> viscosity <SEP> 178
<tb>
 
The mixed isomeric nonyl-diphenyl phosphate of Examples 10,11 and 12 was the same as that used in Example 7.



   In general, for a sufficiently low viscosity at low temperatures, such as -30 F. and -40 F., it has been found that the alkyl group, especially monoalkyl-diphenyl phosphates, should not have more than 8 carbon atoms and preferably less than 6 carbon atoms.



   Still other fluids obtained according to this invention and which do not crystallize at extremely low temperatures, as indicated above, are those obtained from monoalkyl-diaryl phosphate in which at least one of the aryl radicals has at least a methyl substituent, and preferably those in which each of the two aryl groups has at least one methyl substituent, or mixtures thereof with other monoalkyl diaryl phosphates. These fluids are described by the following examples: Example 13: 95% by volume phosphate of 2 (ethyl-hexyl-dicresyl 5% by volume Acryloid HF-855.



   The resulting mixture was tested and found to have the following properties:

 <Desc / Clms Page number 30>

 
 EMI30.1
 
<tb> Point <SEP> of <SEP> freezing- <SEP> 55 F.
<tb>
<tb>



  Viscosity <SEP> to <SEP> 210 F. <SEP> 4.89 <SEP> centistokes
<tb>
<tb> 100 <SEP> 25.1 <SEP> centistokes
<tb>
<tb> <SEP> index of <SEP> viscosity <SEP> 133
<tb>
 Auto-ignition temperature 1.040 F.



   The fluid in this mixture showed no tendency to crystallize at temperatures as low as -50 F.



  Example 14:
 EMI30.2
 95% by volume of mixture of 70 by volume 2-ethyl-hexyl-diphenyl phosphate 30 by volume α-ethyl-hexyl-dicresyl phosphate
 EMI30.3
 
<tb> 5% <SEP> in <SEP> volume <SEP> of Acryloid <SEP> HF-855.
<tb>
<tb>



  Freezing <SEP> point <SEP>- <SEP> 55 F.
<tb>
<tb>



  Viscosity <SEP> to <SEP> 210 F. <SEP> 4.26 <SEP> centistokes
<tb>
<tb> 100 <SEP> 18.0 <SEP> centistokes
<tb> <SEP> index of <SEP> viscosity <SEP> 166
<tb>
 
The fluid in this example did not crystallize at -30 F., as the fluid in example 2 did, but crystallized at -40 F., indicating that the temperature at which crystallization was occurring had been significantly lowered. .



  Example 15:
 EMI30.4
 95% by volume mixture of / 50% by volume 2-ethyl-hexyl-diphenyl phosphate) 50% by volume 2-ethyl-hexyl-dicresyl phosphate
 EMI30.5
 
<tb> 5% <SEP> in <SEP> volume <SEP> of Acryloid <SEP> HF-855.
<tb>
<tb>



  Freezing <SEP> point <SEP> <SEP> -55 F <SEP>. <SEP>
<tb>
<tb>



  Viscosity <SEP> to <SEP> 210 F. <SEP> 4.45 <SEP> centistokes
<tb>
<tb> 100 <SEP> 19.8 <SEP> centistokes
<tb>
<tb> Viscosity <SEP> <SEP> index <SEP> 156
<tb>
 

 <Desc / Clms Page number 31>

 Example 16:
 EMI31.1
 95% by volume of mixture of 30 by volume of 2-ethyl-hexyl-diphenyl phosphate 70% by volume of 2-ethyl-hexyl-dicresyl phosphate
 EMI31.2
 
<tb> 5% <SEP> in <SEP> volume <SEP> \ <SEP> of Acryloid <SEP> HF-855
<tb>
<tb> Point <SEP> of <SEP> freezing <SEP> -55 F.
<tb>
<tb>



  Viscosity <SEP> to <SEP> 210 F. <SEP> 4.49 <SEP> centistokes
<tb>
<tb> 100 <SEP> 21.0 <SEP> centistokes
<tb>
<tb> <SEP> index of <SEP> viscosity <SEP> 145
<tb>
 
The fluids of Examples 11 and 12 above were improved with respect to the temperature at which crystallization occurred as observed for Example 2 and, by the use of nonyl-diphenyl phosphate. mixed isomer, more than 30%, or octyl-dicresyl phosphate as in Examples 9,11,12,15 and 16, the crystallization phenomenon -as observed for the fluid of Example 2 , did not appear.



   The 2-ethyl-hexyl-dicresyl phosphate used in the above examples is obtained from a mixture of ortho, meta and paracresol from which orthocresol is practically removed so that the cresyl radicals of the phosphate are a mixture almost predominantly meta and paracresyl radicals. The proportion of meta and para-isomers is approximately the same, with some predominance of the meta-isomer. The particular 2-ethyl-hexyl-dicresyl phosphate used was obtained from Monsanto Chemical Company, St. Louis, Missouri, under their trademark Santicizer 142. Santicizer 142 is described in Technical Bulletin C-D-111 of the Development Department, Organic.
Chemicals Division, Monsanto Chemical Company, St. Louis, Missouri.



   The properties of this octyl-dicresyl phosphate are given in Table IV below. Table IV also gives the properties of the mixed isomeric nonyl-diphenyl phosphate used in the above examples.

 <Desc / Clms Page number 32>

    



  T A B L E A U IV
 EMI32.1
 
<tb> Phosphate <SEP> of <SEP> 2-ethyl- <SEP> Phosphate <SEP> of <SEP> nonyl
<tb> hexyl-dicresyl <SEP> diphenyl <SEP> isomer
<tb> (Santicizer <SEP> 142) <SEP> mixed
<tb>
<tb> Point <SEP> of <SEP> freezing- <SEP> 50 F. <SEP> - <SEP> 60 F.
<tb>
<tb>



  Viscosity (centistokes)
<tb>
 
 EMI32.2
 2100F. 3, l2 2988
 EMI32.3
 
<tb> 100 <SEP> 16.8 <SEP> 12.3
<tb>
<tb> -30 <SEP> 9.789 <SEP> 4. <SEP> 107
<tb>
<tb> Viscosity <SEP> index <SEP> <SEP> 18 <SEP> 86
<tb>
<tb> Self-ignition <SEP> 1.060 F. <SEP> 1.020 F.
<tb>
<tb> <SEP> index of <SEP> neutralization <SEP> 0.04 <SEP> 0.03
<tb>
 
The following is an example of a composition of this invention analogous to the composition of Example 8 above but in which the alkyl polymer methacrylate was polymerized in part of the mixture of phosphates. Alkyl diphenyl used to make the composition.



  Example 17:
 EMI32.4
 97% by volume of mixture of 50 2-ethyl-hexyl-diphenyl phosphate) 50% of Cg-alkyl-diphenyl phosphate mixed 3% by volume of Acryloid G-5573X
This composition has the following properties:
 EMI32.5
 
<tb> Point <SEP> of <SEP> freezing- <SEP> 70 F.
<tb>
<tb>



  Viscosity <SEP> to <SEP> 210 F. <SEP> 3.54 <SEP> centistokes
<tb>
<tb>
<tb> 100 <SEP> 14.9 <SEP> centistokes
<tb>
<tb>
<tb> 0 <SEP> 416 <SEP> centistokes
<tb>
<tb>
<tb> -40 <SEP> .939 <SEP> centistokes
<tb>
<tb>
<tb> <SEP> index of <SEP> viscosity <SEP> 140
<tb>
 No cloud at - 70 F.



  No crystallization at - 40 F.



   The mixed Cgalkyl-diphenyl phosphate was the same

 <Desc / Clms Page number 33>

 than that used in Examples 7 and 8 above.



   Acryloid G-5573X was polymerized in 55% of the phosphate mixture used in this example to an average molecular weight of about 10,000. It contained 45% of polymers in solution in the mixture of phosphates.



   These compositions according to the invention have been found to be surprisingly satisfactory for transmitting power in parts of an aircraft hydraulic system having a Vickers axial piston pump as a power source, and for lubricating said parts. In addition, these compositions also have a high degree of non-flammability or fire resistance, which makes them eminently suitable as hydraulic fluids for aircraft. These compositions have been found to be particularly suitable as lubricants for the friction surfaces of the hydraulic system. These include in particular the surfaces to be lubricated metal to metal and metal to elastic material, as has been said above. This lubrication is carried out maintaining a film of the composition between the friction surfaces.

   It is particularly surprising that the two functions, on the one hand, of power transmission and, on the other hand, of lubrication, can be provided so satisfactorily by the compositions according to this invention while at the same time such compositions are eminently satisfactory in other fields of aviation use.



   The foregoing disclosure describes preferred aspects of the invention and illustrates it by way of specific examples, but changes and modifications may be made without departing from the scope of the invention disclosed herein.


    

Claims (1)

EMI34.1 R E U E N D I C T I 0 N S. A composition consisting essentially of at least one monoalkyl-diaryl phosphate in which the aryl groups are members of the group consisting of phenyl, cresyl and xylyl radicals and in which the monoalkyl group has 1 to 10 carbon atoms, and one sufficient proportion of a polymerized alkyl methacrylate to increase the viscosity of the composition at elevated temperatures and to increase the viscosity index of the composition. 2. Composition as defined in claim 1, in which the alkyl radical of said phosphate is a branched chain radical. 3. Composition as defined in claim 1 or 2, in which the alkyl radical of said phosphate has from 1 to 8 atoms. of carbon. 4. Composition as defined in claim 1 or 2, wherein the alkyl radical of said phosphate has 4 to 8 carbon atoms. 5. A composition as defined in claim 1, 2, 3 or 4, wherein the alkyl group of said polymerized alkyl methacrylate has 8 to 10 carbon atoms and an average molecular weight of 8,000 to 12,000. 6. A composition as defined in any one of the preceding claims, wherein said polymerized alkyl methacrylate increases the viscosity index to a level greater than 100. 7. A composition as defined in any one of claims 1 to 6, wherein said phosphate is a monoalkyl-diphenyl phosphate. 8. Composition according to any one of claims 1 to 6, consisting essentially of 2-ethylhexyl-diphenyl phosphate and a lesser but sufficient proportion of said polymerized alkyl methacrylate. <Desc / Clms Page number 35> 9. A composition according to any one of claims 1 to 6 consisting essentially of 6-methyl-heptyl-diphenyl phosphate and in a lesser but sufficient proportion of said polymerized alkyl methacrylate. 10. A composition as defined in any one of claims 1 to 6, in which at least one of the two aryl radicals has at least one methyl substituent. 11. A composition as defined in any one of claims 1 to 6, in which each of the two abovementioned aryl radicals has at least one methyl substituent. 12. A composition according to any one of claims 1 to 6 consisting essentially of 2-ethyl-hexyl-dicresyl phosphate and in a lesser but sufficient proportion of said polymerized alkyl methacrylate. 13. A composition according to any one of claims 1 to 6 comprising essentially a mixture of said monoalkyl-diaryl phosphates. 14. A composition as defined in claim 13, wherein the alkyl radicals of said phosphates are branched chain radicals. 15. A composition as defined in claim 13 or 14, in which the alkyl radicals of said phosphates have from 1 to 8 carbon atoms. 16. Composition according to any one of claims 1 to 6, consisting essentially of a mixture of hexyl-diphenyl phosphates in which the hexyl groups are a mixture of isomeric hexyl groups, and a smaller but sufficient proportion of said methacrylate d. Polymetized alkyl. 17. A composition according to any one of claims 1 to 6, consisting essentially of a mixture of heptyl-diphenyl phosphates in which the heptyl groups are a mixture of isomeric heptyl groups, and a lesser but sufficient proportion of said methacrylate d. polymerized alkyl. <Desc / Clms Page number 36> 18. A composition according to any one of claims 1 to 6 consisting essentially of a mixture of octyl-diphenyl phosphates in which the octyl groups are a mixture of isomeric octyl groups, and in a lesser proportion. but sufficient of said polymerized alkyl methacrylate. 19. A composition according to any one of claims 1 to 6, consisting essentially of a mixture of nonyl-diphenyl phosphates in which the nonyl groups are a mixture of isomeric nonyl groups, and in a lesser but sufficient proportion of said alkyl methacrylate. polymerized. 20. A composition according to any one of claims 1 to 6 consisting essentially of a mixture of 2-ethyl-hexyl-diphenyl phosphate and 6-methyl-heptyl-diphenyl phosphate, and in a lesser but sufficient proportion. of said polymerized xalkyl methacrylate. 21. The composition of any one of claims 1 to 6 consisting essentially of a mixture of 2-ethyl-hexyl-diphenyl phosphate and other isomeric octyl-diphenyl phosphates predominantly of 6-methyl-heptyl phosphate. -diphenyl, and in a lesser but sufficient proportion of said polymerized alkyl methacrylate. 22. A composition as defined in any one of claims 13 to 21 in which the alkyl groups are derived from alcohols obtained from a fraction of olefins obtained from petroleum converted into alcohols by reaction with oil. carbon monoxide and hydrogen. 23. A composition as defined in any one of the preceding claims, wherein the proportion of polymerized alkyl methacrylate is from about 0.2 to 10 percent by volume, based on what. the mixture of polymer and phosphate is considered 100 percent. 24. A method of transmitting power and lubricating the friction elements of a hydraulic system comprising a <Desc / Clms Page number 37> pump providing power for the system which comprises transmitting power and lubricating said elements by means of any of the compositions as described in any of the preceding claims. 25. A method of transmitting power which comprises the use, as a transmitting agent, of any of the compositions as described in any one of claims 1 to 23. 26. A method of lubricating friction elements moving relative to one another which comprises maintaining between the friction surfaces of said elements a lubricating film comprising any of the compositions as described in any one of claims 1 to 23. 27. A method as defined in claim 26, wherein said friction members moving relative to one another are metallic. 28. A method as defined in claim 26, wherein the friction elements its moving relative to each other are hard steel on bronze. 29. A method as defined in claim 26, wherein the friction members moving relative to one another are metal on an elastic material.