DE1644865A1 - Hydraulic oil - Google Patents

Description

Hydraulic oil. This invention relates to a novel hydraulic and power transmission oil which is particularly suitable for aircraft, unmanned aerial vehicles and other machines which operate over a wide temperature range and to the process of its manufacture. This novel hydraulic oil is a synthetic hydrocarbon oil of unusual chemical composition, which provides physical and chemical properties that were previously impossible or extremely difficult and expensive to achieve with petroleum fractionation. More specifically, the invention relates to a hydraulic hydrocarbon oil that has the desired physical and chemical properties to an increased degree, such as high flash point, high mean boiling point, high thermal stability and high viscosity index in conjunction with a low pour point and relatively low viscosity.

When operating aircraft, especially at high altitudes and high speeds, over a wide geographical area, it is important that the O1 remains fluid at very low temperatures and at high temperatures of around 120 to 230 ° C (25U to 450 ° C F) has sufficient viscosity and lubricity . It is also highly desirable for the oil to have minimal volatility at the highest working temperatures in order to avoid very large evaporation losses and to reduce the risk of fire and explosions in the event that oil leaks onto hot surfaces during operation. In addition, the oil must be extremely resistant to oxidation and be able to work over long periods of time at elevated temperatures without silting up or other changes in properties which would be detrimental to the functioning of the hydraulic system. Although unmanned aerial vehicles generally do not operate for long periods of time, the physical properties of the oil are extremely critical over a wide range of temperatures.

The petroleum fractionation limitations in the manufacture of hydraulic fluids for modern aircraft are well known. A combination of thorough refining including purification, acid and solvent refining, and / or hardening (desulfurization), either prior or subsequent conventional dewaxing, can be performed to yield 01e from paraffinic crude oils which can be grown at temperatures above about -18 ° C (U OF) have good physical properties. In order to achieve a pour point and fluidity at temperatures required for military aircraft (- about 56 ° C - 7JF) and civilian supersonic aircraft (- about 40 ° C - 4U ° F) are considered necessary, an additional thorough and expensive dewaxing necessary. Such refining and dewaxing is currently carried out at a relatively low level of fluidity in the range of 75 to 100 Saybolt seconds at 38 ° C. (100 oF) . It has not yet been proven commercially that paraffinic oils can be dewaxed from higher levels of fluidity to the necessary pour points as required for military aircraft . A substitute for thorough dewaxed paraffinic oils has been considered is a thoroughly refined oil naphthene from a substantially paraffin-free crude oil. Such available naphthenic oils are limited in their viscosity-temperature sensitivity and have a maximum viscosity index of about 75 . Naphthenic materials, which produce oils with a higher viscosity index , contain too much paraffin and make the oils ineffective at the necessary low temperatures. An even greater disadvantage, show the hydraulic fluids naphthene, is their low boiling range and its greater volatility for a given viscosity at 38 ° C (100 oF), com- pared with the paraffinic oils.

The synthetic hydrocarbon oil of this invention has both a high viscosity index and a low pour point and also exhibits a higher boiling range and lower volatility for a given viscosity than even paraffinic oil. The chemical composition and the method of synthesis of the novel hydraulic fluid are shown below.

So far, many attempts have been made to use various synthetic hydrocarbon oils as a basic ingredient for aircraft hydraulic fluids , but none of the synthetic fluids produced so far has been satisfactory. Isobutylene polymers of low molecular weight do not have sufficient thermal stability and generally only show mediocre temperature-viscosity properties. The heavy residues produced in the manufacture of gasoline alkylate (such as the alkylation of isobutane with butylene and either H2504 or HF as a catalyst) have also proven unsatisfactory. If alkylated benzenes (commonly referred to as polypropyl benzene or dodecyl benzene) were commercially available as a raw material for the production of water-soluble compounds, it was believed that the large boiling residues from the alkylation reaction would provide enough base oils for the production of hydraulic fluids , but such Remnants have been found unsuitable for this purpose. Such hydrocarbons with Detergenzbasis were usually duVch alkylation of benzene produced with polymers of propylene, kept the smaller amounts of ethylene and butylene polymers ent-e. In preparation for alkylation , the propylene polymer is purified to give an average of 9 to 15 carbon atoms per molecule, depending on the properties of the alkylate desired. In industrial processes, the alkylation of benzene with the polypropylene content is carried out with the aid of either A1Cls or HF catalysts.

With one of the alkylating active ingredients, a small part of the reaction product boils above the area which can be absorbed in the water- soluble detergent base . Such residues have been used successfully in the manufacture of secondary plasticizers for vinyl resins and as a raw material for sulforation to produce oil-soluble sulphonates . These heavy residues and part of them show fairly good thermal stability but their main shortcoming as regards their use as hydraulic fluids is their markedly poor viscosity-temperature properties, as illustrated by viscosity indexes generally less than zero. Their volatility is also quite high for a given viscosity and appears to be related to their low viscosity index . It is generally believed that synthetic oils made by polymerizing olefins such as butylene are comprised of highly branched chain structures and are essentially free of cyclic structures. Where the polymerized olefin is used to alkylate benzene, regardless of whether the alkylation with HF or A1C13 carried leads is, the side chain structure on a branched structural. In the course of the alkylation it becomes apparent that some of the olefin polymerizes before the alkylation actually takes place, with the result that high boiling residues are formed. It also shows that some of the high boiling residues are the result of poly-alkylation and di- or tri-alkyl benzenes yield. In any case, the side chains have a branched structure.

It has now been shown that oils having the desired characteristics in hydraulic oils that have not been found so far to a large degree in hydrocarbon oils can be produced with hydrocarbon structures in which a linear paraffin chain with a Myl group is interrupted. The preferred paraffin chain is 20 to 30 carbon atoms in length and the preferred number of carbon atoms in it is from about 26 to 36 with an empirical formula of CnH2n-6 # A typical hydraulic oil with this chemical structure has the following properties: Viscosity - SSU at 38 0C (100 ° F) 141 viscosity index - 1U3 boiling point - 50,% at 10 mm 260 0C (50000 pour point - - 400C (-400F) flash point - 225 0C (440 0F) specific gravity - at 15.5 0C (60 0F) 09864 aniline point 750C (168 0F) 01e with the desired paraffin structure interrupted by phenyl can have the phenyl group at various points along the chain from the 6th to the 15th carbon atom. The following structural formulas illustrate the composition of the new hydrocarbon hydraulic oils: 1. General formula R = hydrogen or a methyl group n = number of carbon atoms from 6 to 15 within brackets. M = number of carbon atoms from 14 to 24 within brackets Ph = the phenyl group n + m = 20 to 30 2. Special example (a): - CH - CH - CH - 'CH, @ - CH CH 3 - CH 2; 4 2 6 4 2 2; 12 3 3. Specific example (b): CH 3 - C CH 3 2 - CH 2 - CH 2 - C6 H4 - CH 2 -. CH 2 20 - CH 3 4. Special example (c): CH 3 - CH 2 12 - CH 2 - C6 H4 - CH 2 - CH 2 12 - CH 3 The synthesis of the above-described hydrocarbons with a straight chain interrupted by phenylene is described in the following examples: Example 1 monoalkyl benzene was treated by alkylating the benzene with a C6 to Cy alpha olefin using hydrogen fluoride as the alkylating agent and a theoretical benzene excess of about 20%. The oilefin used was part of the thermal breakdown of paraffin wax and had a boiling range of about 61J to 150 ° C (140 to 30U ° F). After removing the unreacted benzene by distillation, the monoalkyi-benzene was alkylated again with an alpha-olefin having 16 to IU carbon atoms. After removing the unreacted olefin and hydrogen fluoride, the final alkylate had the properties shown in column 3 of the table. This oil was subjected to laboratory tests to determine its usefulness as a hydraulic fluid and was found to be satisfactory.

Example 2: Benzene in excess was essentially with a propylene Dimer alkylated, which has an average carbon content of about 6 carbon atoms per molecule with essentially a straight chain structure. Hydrogen fluoride Was used as an alkylating agent. After removing the catalysts were unreacted propylene dimer and benzene removed by distillation.

The resulting mono-hexyl-benzene was then re-alkylated with a C16 to C20 alpha-olefin using hydrogen fluoride as a catalyst. The unreacted olefin and the hydrogen fluoride were removed and the finished alkylate showed the properties given in column 4 of the table. The oil was subjected to laboratory tests and found to be a suitable hydraulic fluid.

Example 3, benzene was alkylated with an alpha chlorinated paraffin, having 12 to 14 the Kohlenatoffetome per molecule and a straight chain, A1C13 was used as catalyst. The catalyst was removed and the reaction product was distilled to remove the unreacted benzene, monoalkyl and dialkyl benzene . Additional chlorinated paraffin was then added to the monoalkyl portion and reacted in the presence of additional A1C1J catalyst. The product was then neutralized to remove the catalyst and distilled to recover the dialkyl benzene from the higher boiling residue and the monoalkyl benzene. The properties of the dialkyl benzene product are shown in column 5 of the table. Particular attention should be paid to the low pour point of - 48 C (- 55 ° F) in conjunction with a flash point of 22 ° C (430 ° F). Example 4: A petroleum bed tail from a paraffin-based crude such as Pennsylvania-U1 boiling in the heavy naphtha range was fractionated on an alumina-silica gel type molecular sieve to recover the normal or straight chain hydrocarbons. Other types of molecular sieves can be used, such as urea crystals, preferably in combination with methane. The normal hydrocarbons have been chlorinated, primarily in the alpha position, using an excess of hydrocarbon to avoid dichlorination as much as possible. The monochloroparaffin thus obtained was reacted with benzene or with monoalkyl benzene to give in the presence of a Friedel-Craft catalyst such as NF, BF3 or A1 C13 dialkyl benzene. The product of this reaction, which is a dinormal alkyl benzene or a long chain hydrocarbon paraffin interrupted by a phenylene group, had a dark red color and other properties as shown in column 5 of the table. It was treated with 20 percent by volume of oleum (25% so 3) at normal temperature, neutralized with sodium hydroxide, washed with secondary butyl alcohol and extracted in order to remove the sulfonated products. The treated 01 was nearly colorless and was characterized by the features indicated in column 6 of experimental data. Example 5: That in column? The oil shown in the table was a linear alkyl benzene with a long chain and only one alkyl group. It was treated in the same manner as the dialkyl oils just described, but using a higher molecular weight alpha olefin which gives an oil of approximately the same viscosity at 99 ° C (210 ° F). It should be noted that the viscosity index is quite high, but the pour point is also high, making the oil completely unusable for most hydraulic oil applications. Structurally, this oil is a hydrocarbon paraffin which contains a phenyl group and no phenylene group. Example 6 :. Thermal stability the described in column 6 of the table almost colorless 01 was sealed in a glass bomb tube without air and heated by the tube for 6 hours in a bath maintained at 340 ° C (65U oF) bath of molten lead was dipped the 01. remained colorless and experienced only a slight decrease in viscosity. Although the present invention has been described with reference to specific examples thereof, it is intended to include the following modifications and variations thereof. If, consequently, benzene is alkylated with monochloro paraffin, dichloro paraffin cannot be completely ruled out and, in fact, monochloro paraffin can contain 5 to 10% dichloro paraffin, which when aromatizing? Pol # rhenyl paraffin hydrocarbons results, which have undesirable properties for hydraulic oil. When such polyphenylene paraffins are present , usually to the extent of about 2 to 10 percent, they can be removed by refining with concentrated H? SO4, usually 10 to 25 percent by volume of oleum.

When treating olefins for the process of the present invention by cleaving paraffin wax, it is desirable to employ high temperature thermal aging of about 480 to 600 ° C (900 to 1100 ° F) for short times of 10 seconds to 2 minutes. The cleaved product is fractionated to obtain those constituents described above. Thus, an olefin moiety having about 10-14 carbon atoms has been found useful in the manufacture of water-soluble detergents for household use by benzene alkylation. The lighter and heavier olefins are then used to alkylate benzene as described above for hydraulic oils of 25 to 35 carbon atoms. Another source of alpha olefins for making hydraulic oil of the present invention are the natural fats, all of which are straight Chain or have a normal structure. Thus, olein or stearin can be hydrogenated to stearyl alcohol using a Raney nickel catalyst with hydrogen under high pressure. The alcohol is converted to alpha-chloro raraffin by adding P C15, PO C13, H Cl, or other chlorinating agents to build. Lighter fats, such as those found in palm oil, castor oil, and coconut oil, can be used to make hydraulic oils by this process. Alpha-ChlorDaraffins can also be removed from unsaturated carbon dioxide by means of dav. Oxo processes are produced in which an olefin is reacted with carbon monoxide and hydrogen to produce a primary alcohol which contains one more carbon atom. Conversion of the alcohol to the halo and the alkylation of benzene as described above then produces the dialkyl benzene or the phenylene interrupted hydrocarbon paraffin which is the unusual basis of the hydraulic oil of the present invention. Various additives are preferably added to the original hydraulic oil of the present invention in order to improve resistance to oxidation, the viscosity index. to improve it, to reduce wear and tear or for other purposes. Thus, 'in anti-oxidant in a Menp-e v,) r his 0.1 -1% are ziig-efft and. a hindered phenol is preferred for this purpose. used, such as di-tertiary butyl paracresol, aromatic amines, aminophenols, phenothiazine, zinc dithiophosphate ect. can also be used under certain conditions. As an anti-wear agent, tricresyl phosphate has been found to be satisfactory in the: Amount of 0.5 to 5% .-- Zur Vnrhi-ssrr, 2np; of the viscosity index, the various types of "^.cr@Tloi3" manufactured by Rohm-ßc Haas can be used. Preferably, the polyolefins, particularly the polybutenes, manufactured by Standard 01 Co., New Jersey, under the name "Paratore N", or the polybutene manufactured by Chevron Chemical Co., designated No. 24 (840 molecular weight), No. . 32 (120e molecule 3r? Awicht) or Xr. 128 (1500 molecular weight) can be used. These viscosity index improving agents: F are completely, partially; _P variable with the synthetic phenylene paraffin oil of this invention and are usually used in the amount of 1 to 10% by weight.

Claims (7)

Patent no. 1. Coal water @ toff-Hvdraitliköl, characterized by a viscosity, with the range from @iO to 200 according to Saybolt at 38 OG (1n0 oF), an average boiling point of 230 to A ZO 0C (4G0 to 4 600 ° F) at 10 mm pressure, a -specific weight according to API of Atwa 28- to 33 at 15.3_ ° C (t @@ ': ° F), a pour point of untni- = 40 ° C and a viscosity index of about 95 bi .-, l? 5, tiobri der -hydrocarbon - following formula on west: R. # - Ph - R2 where Ph is a phenyl group, R1 is a hydrocarbon-paraffin group with a linear chain containing 6 to 15 carbon atoms aufweisj't, is and R2 Pi ^ e carbon dioxide, material group with linear K-'tp, rie from 12 to ?? Has carbon atoms, the total number of carbon atoms in the R group is from 2n to 30 and the linear chains consist of unbranched chains of carbon atoms replaced by hydrogen and MPtlivl _ ".; roots. 2. Hydraulic oil according to claim 1, d a d u r c h g e k e n n -, z e i o h n e t, that the phenylene group is an nrtho-Phenvleri group is: 3. Hydraulic oil according to claim 1, - d a d u r c h g e k e n n -z e i c h n e t that the phenylene group is a Para-Phehylen = group. 4. The method for producing the hydraulic oil according to claim 1, characterized by: 1) fractionating a crude oil distillate to obtain a constituent of 6 to 22 carbon atoms which boils in the range of about 65 to 320 ° C (150 to 600 ° F); 2) Separation of the constituent into linear and non-linear hydrocarbons by selective absorption of the linear components in a molecular sieve, followed by desorption of the linear constituents; -3) -fractionation of the linear hydrocarbon mixture into a series of nearby boiling parts each having a boiling range less than 10 ° C: (50 ° F); 4) the chlorination of the nearby boiling parts with no more than half the molar equivalence of chlorine, whereby over-. mainly alpha- monochloroparaffins are produced; 5) fractional distillation: each chlorinated paraffin part into a lower boiling, non-chlorinated hydrocarbon part, a monochloro paraffin part and a higher boiling polychlorinated paraffin residue; -6) the removal of the polychlorinated paraffin residue and the return of the non-chlorinated part to section 4 of the process; 7) the aromatization of the monochloro-paraffin part by the action of an excess of benzene in the presence of a Friedel-Craft catalyst; 8) the separation of: the resulting aromatized paraffins by fractional distillation into dialkyl benzenes, monoalkyl benzenes and heavier polyalkyl benzenes ;: the separation of the polyalkyl benzenes and the re-alkylation of the monoalkyl benzenes with monochloro paraffin, whereby further - Quantities of dialkyl benzenes for use in hydraulic oil are produced. , 5. The method according to claim 4, dadurc h. I labeled in z'e t e n that the Konoalkyl-benzenes in step 8 de = s method deposited and in step 7 of the process are recycled, where they are converted by reaction with monochloro-paraffins to dialkyl benzenes. - 6. Procedure according to Claim 4, d a d u r c h e k e n n -z e i c h n e t that the lower boiling Monoalkyl Benzo? Parts, from level 8 with the higher boiling monochloro paraffin parts-from Stage 5 are alkylated, whereby dialkyl .benzenes with predominantly dissimilar alkyl groups getting produced. 7. A method for producing the hydraulic oil according to claim 1, characterized by 1) the alkylation of benzene with Prcpylen-Dime-r and a Friedel-Craft catalysts, whereby monohexyl-benzene is produced; 2) the separation by fractional distillation of the monohexyl benzene from the non-alkylated benzene and the polyalkyl benzene; 3) the alkylation of monohexyl benzene with a linear alpha chlorohydrocarbon paraf. «fin from 14 to 22 carbon atoms in which the carbon chain is saturated with hydrogen and methyl roots; 4) separating by fractional distillation of the resulting monoalkyl-hexyl-benzola from the lower-boiling unreacted hexyl-benzene and from the higher-boiling residue; returning the abeeschiedenen in Step 4 of the process unreacted hexyl benzene-part in the step 3 of the method: