DE862206C - Mineral oil based lubricants - Google Patents

Description

Lubricant based on mineral oil The present invention relates to improvements in Schmiennitteln mineral-based, in particular those for use in internal combustion engines or -kraftmaschinen which can be powered by gasoline or 01. In the latter case, the invention is mainly applied to the so-called heavy duty lubricating oils, such as those used in diesel or other types of oil engines.

The main aim of the invention is mineral oil-based lubricants to create, in which their tendencies towards the formation of products, which opposite Metals, e.g. B. metal bearing surfaces, are corrosive, and harmful oxidation products are turned off. The invention further aims to provide lubricants To create a mineral oil base that also has cleaning properties and during * Let the machine run smoothly when possible, namely by preventing the deposition of resin or rubber or paint in the lubricated parts as well as the fact that any solid particles and sludge formed are kept in suspension in the lubricant. Such properties are for the work of oil engines, such as B. Diesel engines, v ion of particular importance.

It has already been suggested to make certain metal salts more organic Add dithiophosphoric acids to lubricating oils.

Such additives are generally known to impart good resistance to oxidation to the lubricating oil, and to a greater or lesser extent, the formation. of products - to prevent corrosive effects on assembled metal bearings.

Some of these additives also have cleaning or sludge-dispersing properties ! the straight-chain alkaline earth metal salts of dithiophosphoric acids containing 10 or more carbon atoms - are particularly effective in this regard.

It has been found, however, that such dithiophosphates of relatively high molecular weight are much less effective in preventing oxidation and bearing corrosion than those of low molecular weight, whereas the latter, in turn, are relatively ineffective as cleaning and sludge dividing agents. It has now been found, surprisingly that oil-soluble metal salts of organically disubstituted dithiophosphoric acids, which are at least partially derived from a saturated aliphatic oxyether, not only have the property of preventing oil oxidation and bearing corrosion to an excellent degree, but also have the property of separating resin, varnish and Significantly reduce carbon, which would otherwise be produced by the oil in which it is dissolved when it comes into contact with hot metal surfaces. will.

In this regard, corresponding chromium salts and corresponding salts of metals of the second and third groups of the periodic table, e.g. As appropriate alkaline earth and zinc salts, especially effective, but also corresponding salts of other metals are very satisfactory from the standpoint of additives' värliegenden invention of view, especially in the prevention of oxidation and corro- sion * of composite metal bearings is concerned.

The additives according to the present invention impart the lubricating oil also improved film tear strength.

According to the present invention, a lubricant based on mineral oil contains a low content of oil-soluble metal salts of organically disubstituted dithiophosphoric acids, which are derived at least in part from a saturated aliphatic oxyether. Such oil-soluble metal salts preferably have the general formula in which n represents the valence of the metal M, Rl is a saturated aliphatic radical which contains an ether group. and R, is the same or a different organic radical, preferably a saturated - -aliphatic radical with at least 5: carbon atoms or an alkylated aromatic radical.

. A type of the metal salt, the above characteristic, which the present invention is incorporated into a mineral oil base Schiniermittel invention is a such, which is derived from tetrahydrofurfuryl alcohol, d. H. a salt in which the radical R of the above formula is a tetrahydrofurfuryl radical illustrated by the formula The radical R., then, is any other suitable organic radical since the di-tetrahydrofurfuryl dithiophosphates are insoluble in mineral oil-based lubricants.

Examples of other gliphatic oxyethers, of which the metal salt can be derived, are ethylene glycol monobutyl ether (C4H, OCH, CH, OH), diethylene glycol monoethyl ether (C2H, OCH, CH, OCH, CH, OH), 3-methoxy-n-butanol and triethylene glycol monobutyl ether.

Examples of organic hydroxyl compounds, of which the radical R, which can be derived from the above formula in a suitable manner, are aliphatic Alcohols, e.g. amyl, octyl, lauryl or cetyl alcohol, alicyclic alcohols, z. B. cyclohexanol or methylcyclohexanol, phenols, especially alkylated phenols, z. B. octylcresol, p-octylphenol, p-tertiaryamylphenol or tertiary butylcresol, aromatic Alcohols, aliphatic oxyethers, as already mentioned above.

Suitable radicals for R: 1 and R 1 in the general formula given above will all be such that the disubstituted metal salt is soluble in the mineral oil base. The radical R should have at least 5 carbon atoms.

Specific examples of disubstituted phosphorodithioic acids of which a metal salt is used according to the invention are tetrahydrofurfuryloctylcresyldithiophosphoric acid and di- (ß-butoxyethyl) phosphorodithioic acid, 3-methoxy-n-butyl-2-ethoxy-n-butylphosphoric acid .

The soluble metal salts of any of the following metals can be used: barium, calcium, strontium, magnesium, zinc, aluminum, nickel, cobalt, tin, cadmium, chromium, manganese and thallium # Preferably an amount of 0.2 to 2.0 percent by weight is used of the metal salt of the lubricant 7. Medium added, and according to a particular embodiment of the invention, the lubricant can also contain small amounts of metal-petroleum sulfonates, eg. B. of alkaline earth or tin-petroleum sulfonates are added. - Such additives are preferably used in a Mengenanteil- of o, o5 to 2, o percent by weight added to the Schmierrnittel. In particular in the case where a chromium dithiophosphate is used, such an additional content of metal-petroleum sulfonate, in particular tin-petroleum sulfonate, is advantageous.

Some of the within the scope of the present invention - as an additive to lubricants Metal salts provided on a mineral oil basis have only a limited degree of Solubility in, mineral oil. True solutions of such connections can, however, thereby can be obtained by first dissolving them in concentrated oil solutions of the metal petroleum sulfonates dissolves and then dissolves in the mineral oil in the desired proportion causes.

Examples of compounds with limited oil solubility, which can be brought into solution in this way are zinc salts of di- (2'-butoxy-2-ethoxyethyl) -dithiophosphoric acid, Calcium salt of di- (ß-butoxyethyl) -dithiophosphoric acid, cobalt salt of 2'-methoxy-2-ethoxyethylmethylcyclohexyldithiophosphoric acid.

However, it is preferred to use salts which are free or in the desired proportions in minerals 61. are readily soluble, and when compounds such as 3-methoxy-n-butanol, ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetrahydrofurfuryl alcohol, etc., are used to create the 1Z1 radical, the R radical, preferably an aliphatic chain, should be used # Include sufficient length to. to give adequate oil solubility to the final metal salt.

The metal-petroleum sulfonates, which, in combination with the. Compounds of the present invention may be used are those which are of the oil-soluble petroleum sulfonic acids, which are known as mahogany acids derived and generally a Molekularg, desired weight in the range of 40o to 5oo besitzen_ Erdölsu 'lfonate jeweden polyvalent metal, or mixtures thereof may can be used, with the tin salts being given particular preference. However, other metal salts can also be used with good results, e.g. B. such. of calcium, barium, strontium, magnesium, aluminum, chromium, manganese, cadmium, nickel, cobalt, zinc and thallium.

The common use of metal-oil # sulfonates and metal dithiophosphates of the inventively provided Art. Creates lubricants that possess excellent cleaning properties, such lubricants occur as high-performance lubricant for use in high-speed diesel engines in which high loads and piston temperatures * are especially suitable .

The preparation of the oil-soluble metal salts organically disubstituted Dithiophosphoric acids of the type mentioned above are expediently accomplished in the manner that first the aliphatic oxyether was brought to reaction with phosphorus pentasulphide and if a mixed organic dithiophosphate is desired, a suitable organic hydroxyl compound with the oxyether for simultaneous reaction -be mixed with the phosphorus penthsulphide. The acid can be replaced by sodium hydroxide neutralized and a desired metal salt by adding a suitable salt of said metal are generated.

The preparation of the additives, which as such is not claimed here, can, for. B. in the following way: Examples I. Preparation of Chromtetrahydrofurfuryloctylcresyldithiophosphat. '772 g of tetrahydrofurfuryl alcohol are mixed at 1650 9 octylcresol in a 5-1 bottle, 130' heated and treated with powdered Phosphorpentalsulfid GI5 g, which is added in small amounts with stirring. The temperature was held at 130 to 140 'for about 30 minutes until the reaction was essentially complete and most of the phosphorus pentasulfide had disappeared. The reaction was then completed by slowly heating to 150 'and maintaining this temperature with stirring for 5 minutes.

After cooling, the product was dissolved in petroleum ether and filtered off some sulfur and unreacted phosphorus pentasulfide, the solvent. was then distilled off under reduced pressure to give an amber color viscous liquid. It will be perceived that in addition to the mixed Thiophosphate in this liquid has lesser amounts of di (tetrahydrofurfuryl) dithiophosphate and of di- (octylcresyl-) dithiophosphate are present, the acidity of the product, that by titrating an alcoholic solution with standard sodium hydroxide solution when m-t was determined in the presence of a phenolphthalein indicator corresponded to an apparent one Molecular weight of 457 (theoretical 417) and indicated that the reaction led to gi 0 /, was complete.

94 g of this reaction product were then mixed with 840 cm3 of water in a 3 l beaker, heated to 40 to 50 'and made just alkaline to phenolphthalein by adding 10% sodium hydroxide solution with stirring. This aqueous solution of sodium thiophosphate was then heated to the top and a further small amount of sodium hydroxide was added to give a clear solution just alkaline to phenolphthalein.

370 cH0 of almost boiling 10% aqueous chromium alum solution were slowly added to this solution with stirring, the purple chromium salt of the dithiophosphate being precipitated as a viscous liquid.

After cooling, the aqueous solution was decanted from the almost solid substance, which was then dissolved in 500 cm3 petroleum ether, dried by refluxing under a constant water separator, filtered off from an amount of insoluble green solid and freed from the solvent by distillation. The yield was 7-5% of theory.

The - Product> containing 2, o2 0 /, chromium, while -the calculated chromium content 3.79 0/0 accounted for what a Umsetzüng ent to the chromium salt of 53 04 - spoke, with the major impurities free dithiophosphoric its sodium salt and were some amount of free octyl cresol produced by hydrolysis.

It was later found that by carrying out the precipitation at 5o to 6o 'a better conversion for the chromium salt could be achieved.

It will be understood that using the compounds of the present invention either pure metal salts or mixtures such as. B. the product of Example I can be used. ' Although lesser amounts of the -free phosphorodithioic acids and their sodium salts in the -products do not interfere, it is preferred to use materials which contain no more than about 20 % of the free acid (and preferably less) and no less than about 65 "/, containing the salt of a polyvalent metal ..

If desired, the remaining free acid can be removed by heating of the product (preferably in oil solution) with a metal oxide or hydroxide (such as z. B. zinc oxide or calcium or barium hydroxide) are neutralized to z. B. a mixture of chromium and zinc salts along with a lesser amount of sodium salt to create.

The product of Example 1 is represented by the formula - illustrates. II. Preparation of zinc di (butoxyethyl) dithiophosphate.

Ethylene glycol monobutyl ether (47.8 g) was placed in a 100 cm3 round-bottom flask, heated to 120 'and reacted with 22.2 g of phosphorus pecite sulfide, which was added in small amounts with stirring. A vigorous reaction resulted with evolution of hydrogen sulfide, and the solution became clear in a few minutes with the exception of a small amount of sulfur and other impurities at the bottom of the vessel. The pale yellow liquid thus obtained was dissolved in 100 cm 3 of petroleum ether, filtered and the solvent removed by distillation.

The acidity of the product corresponded to a molecular weight of 370 (calculated 330), i.e. H. conversion to the dithiophosphate was 88% complete.

18.5 g of this substance were mixed with 100 cm3 of water and just made alkaline to phenolphthalene at room temperature. The solution was then heated to go ', decanted from a small amount of brown oily liquid which separated out, and treated on go' with a slight excess of hot aqueous zinc chloride solution. A white opaque liquid was excreted.

After cooling, the 'aqueous solution was decanted and the product was dissolved in petroleum ether by refluxing under a constant water separator dried and filtered, after which the solvent is finally distilled was removed.

The zinc salt was clear, pale yellow liquid, easily soluble in 01.

- The product of Example II is represented by the formula illustrated. III. A Schmiermittelzusanimensetzung was - generated incorporation of o, 8 percent by weight of the product of Example I and o "2 0/0 tin petroleum sulfonate in a mineral lubricating oil base.

IV. Preparation of Kadmimu di (β-butoxyethyl) dithiophosphate.

33.5 9 di- (p-butg-7cyäthyl) dithiophosphate, which were prepared as described in Example II were mixed with 636.5 cm3 of water, and sodium hydroxide was gradually added with stirring at room temperature until the complete neutralization was. The solution was filtered from some insoluble material, heated to 50 'and contained with a warm io0 /, solution which is 1? "5 9 cadmium chloride, treated, after which the cadmium salt was precipitated as a yellowish white crystalline solid.

After recrystallization from petroleum ether, it was obtained in the form of fine white needles in a yield of 36%. It contains 15.2% cadmium compared to a theoretical cadinium content of 14.6% for the pure salt.

V. Preparation of the zinc salt of 3-methoxy-n-butyl-2-ä.thylhexylclithiophosphoric acid. Following the procedure of Example II, the reaction resulted in a mixture of 32.5 9 7-methylhexanol and 26 9 3-methoxy-n-butanol with 27.8 g of phosphorus pentasulfide for 15 minutes at 1 to 10 and finally 5 minutes at i? oo 75 g of 2-ethylhexyl -3- methoxy - n-butyldithiophosphoric acid were obtained, which represented a yield of gi 0 / . The molecular weight was 375 compared to a theoretical value of 3z8.

37.5 g of this material was mixed with 4.4 9 of zinc chloride and slowly heated with stirring for about 2o minutes to 135 ', after which the product is cooled, dissolved in petroleum ether, filtered off from excess zinc oxide. and freed from the solvent by distillation.

By e; n such a procedure 36.6 g * were obtained (gi 0/0 yield) of a yellow liquid viscosen which 0 /, containing 6.46 zinc as compared to a theoretical content of 7.70 (lo.

The procedure of Example V is generally applicable to the preparation of the zinc and magnesium salts contemplated by this invention, while the procedure of Example IV is broadly applicable to the salts of any of the polyvalent metals. However, other known methods can also be used, e.g. B. the direct reaction between the free acid and a metal oxide in alcoholic-benzene solution at 40 to 50 ' (applicable in particular to the alkaline earth and magnesium salts) or the direct reaction between a metal hydroxide, such as. B. barium hydroxide, and free acid by joint heating in mineral oil solution in the presence of a stream of air to remove released water.

If necessary, a metathesis in alcoholic solution between an alkali salt of phosphorodithioic acid and an alcohol-soluble metal salt are executed.

The product of Example V is represented by the formula illustrated. Test Results Various examples of the invention are given below in connection with the results of tests which serve to illustrate the effectiveness of the lubricant compositions contemplated by the present invention in various respects.

For comparison purposes, the test results also include those one made with unmodified lubricating oil bases such as those used to generate the examples of lubricants of the type proposed according to the invention are used and also, in certain examples, with metal dithiophosphates, as they have already been were known for these purposes.

The components of said lubricants are given in percentages by weight in all tests. Test i: Oxidation Resistance As a means of testing the oxidation resistance of the lubricants proposed in the present invention, a modification of the well known oxidation test according to British Air Department regulations was used. The lubricants were oxidized under the standard British Air Department Oxidation Test conditions except that a temperature of 16o 'was used and that a copper catalyst consisting of a rolled, polished piece of copper foil 57J5mm X 25.4mm was present. The catalyst was replaced with a fresh catalyst at the end of the first 6 hour oxidation period. The test results obtained were: Viscosity Acidity Insoluble in Test lubricant composition increase (mg KOH) petroleum ether No. CM per gram (boiling point under 40 ') I Oil A (average sample) ................ 33.6 1.00 0.45 2 oil A + 1 0 /, manganese-3-methoxy-n-butyl- .l2-ethylhexyldithiophosphate ............... 23.8 0.56 very faint trace 3 A + 0.5 ') /, cobalt-2-methoxy-2-ethoxy- ethylmethylcyclohexyldithiophosphate *) + i, o 0/0 cadmium petroleum sulfonate ........ 23.5 0.45 the same. This compound contained approximately 72% current chromium salt. The additives marked with an asterisk were not soluble in mineral oil in the proportions used in the absence of the metal-petroleum sulfonate.

The 01 A, as used in these and the following tests, consisted of 940 /, of a mixture of a dissolving refined mineral oil of the paraffinic type with a viscosity of about 150 seconds Redwood at 60 'and of 6 0 /,) of a Mixture with a viscosity of about 330 seconds redwood at 6o 'containing a gloss stick. Test 2: Bearing Corrosion The following test was used to provide information on the tendency to corrosion of composite metal bearings, in particular copper-lead bearings, such as occur when lubricants of the type contemplated according to the invention are used.

400 1111 lubricants were weighed into 150 ml rimless beakers, eight of which were heated in an electrically heated oil bath surrounding them, which was thermostatically controlled to keep the lubricant temperature at 140 °. The beakers were fitted with closely fitting aluminum lids that had central slots that were normally closed but opened to allow a specimen to be inserted. The slits left central when closed. arranged steel stirring rods provide sufficient space for free rotation. The latter were electrically driven by an axle driven in the usual way with 400 zL 40 revolutions per minute and had slotted holders at their lower end. Lead specimens were attached by means of screws. For the specimens, rectangular plates of pure lead 44.45 mm by 25.4 mm were attached vertically just below the surface of the lubricant with the longer axis horizontal. As catalysts, copper strips, 7 mm wide and bent in a semicircle of 95.75 mm in diameter, were placed completely below the surface of the lubricant and connected to corks by means of vertical copper wires, which were attached to the cup lid. each beaker was also equipped with a thermometer.

Tests were carried out for a maximum total time of 30 hours in periods of 6 hours, the copper and lead pieces being removed every 2 hours and replaced with fresh, bare pieces. The copper catalysts were cleaned with silicon carbide powder and washed in petroleum ether. The lead specimens were smoothed, scraped off with a special Skartsen scraper, and finally polished by brushing in one direction with a type of stiff wire brush known as file carding before washing in benzene and weighing. After a period of 2 hours, another wash in benzene, brushing with a camel hair brush, and reweighing were carried out. The total corrosion in any given time was calculated by adding up the weight losses of the lead specimens after each two hour period. These total losses were calculated against the time, and the curves thus obtained were used to read the times which are necessary to achieve certain specified corrosion losses. The following results were obtained: Lead test piece Weight loss passed up to hours test lubricant composition (-g) a weight loss of No. after 12 hours 18 hours 20 mg 1 50 mg 1 100 mg 4 Oil A (average sample) ..................... 2.38 - 4 6 8 -5 ÖIA + 0.5 0/0 tin di (ß-butoxyethyl) dithiophosphate 28 44 6 20 29 6 oil A + 0.5 0 /, nickel-ß-ethoxyethyllauryldithio- Oil phosphate .................................. 24 2.7 9 over 30 - 7 A. + 0.4 0 /, zinc di- (3-methoxy-n-butyl) -dithio- phosphate *) + i, o 0 /, calcium petroleum sulfonate ... 14 65 15 17 20 8 Oil A + -0.5 0/0 Cadmium di (ß-butoxyethyl) -dithio- phosphate + 2, o 0/0 barium petroleum sulfonate ..... 12 18 20 over 30 - 9 - Oil A + o, 6 0 /, magnesium di- (9, '- butoxy-2-ethoxy- ethyl) dithiophosphate *) + i, o 0 /, nickel petroleum Sulphonate .................................... 35 97 8 13 18 io oil A. + 0.4% Chromtetrahydrofurfuryloctylcresyl- dithiophosphate *) + o, 1 0/0 tin-petroleum-sulfonate. . 17 58 13 17 20 This compound contained approximately 72% current chromium salt. Test '3: Resin, Lacquer and Carbon Formation A simple test was devised to determine the tendency of oils to deposit resin, lacquer and carbon on hot metal surfaces, e.g. B. piston walls and heads to compare in internal combustion engines.

Rectangular aluminum blocks (3o4,8 mm X 5o, 8 now X 6.35 mm) were prepared by rubbing with pumice stone and water, and finally. cleaned by washing with petroleum ether. They were then clamped in a special holder at an angle of 25 ' to the horizontal and heated at the upper end by means of a Bunsen burner.

It became such a steady one. Get temperature rises under the block, the block was shielded from the flame by means of an asbestos sheet.

- The 01 to be tested was then dripped from a burette onto a point of the block, the temperature of which was 3500 (measured by a pyrometer), to an extent of approximately 1 cm3 per minute for a total of 30 minutes, after which the block allowed to cool and was washed free with petroleum ether of 01.

In this way deposits were obtained on the blocks consisting of a peripheral ridge of resin "which had the shape of an inverted V and a central spot of lacquer or carbon which varied in color and extent depending on the oil tested Test repeatability was good.

It was found that the addition of small amounts of many of the additives of the present invention to a selected mineral oil caused a very significant reduction in the amount of resin, varnish and carbon deposited, particularly in relation to the central portion of the deposit. To express the results numerically, the following measurements of the deposits were made: a) maximum width of the peripheral resin ridge, b) average width of the peripheral resin ridge (mean of 8 to 10 measurements), c) maximum expansion of carbon or varnish of different colors vertically below the Tip of the oil drop point.

This central part often consisted of several different types of lacquers that were arranged on top of each other. The data given have been taken through Measure from the top of the oil drop point to the lowest point at which Paint of a special type could be perceived.

Four types of varnish were noticeable: i. a deep black deposit of carbon,? - a dark brown deposit of lacquer, 3. a light brown deposit of lacquer, 4. a pale yellow deposit of lacquer.

i and 2 corresponded to class 5 on the Lauson flask classification map, 3 corresponded to about class 4, and 4 to about class i. The following results were obtained: (Oil B was a paraffinic type solvent refined mineral oil having a viscosity of about 150 seconds of redwood at 6o '.) Peripheral central deposit Resin ridge vertical dimensions of the paint Test Lubricant Composition Max Diameter (MM) No. Wide wide black, dark, light, yellow (MM) (MM) brown brown II Oil B (average sample ) ........... 517 2.9 31 50 6o 12 oil B + 0.5 "/ o zinc di (a-methylisoamyl) - dithiophosphate ..................... 6.8 5.3 34.5 49.5 6o 13 Oil B + o, 5 0 /, zinc di (2-ethylhexyl) di thiophosphate : ...................... 8, o 4.3 12 27 36 46 14 Oil B + 0.5 % zinc di (fl-butoxyethyl) di- thiophosphate ....................... 5.5 3.5 1.5 1.5 8.5 36 15 Oil B + 0.5 % zinc-3-methoxy-n-butyl- 2-ethylhexyldithiophosphate .......... 2.5 1.4 nothing 4.0 15 27 16 oil B + 0.5 0/0 aluminum-ß-ethoxyethyl- lauryl dithiophosphate ................ 6.8 3.0 6 20 - 17 oil B + 0.5 "/, nickel-ß-ethoxyethyl lauryl dithlophosphate ..................... 4.2 1.5 nothing 1.0 12 25 18 oil B + 0.5 0/0 nickel (methyleyclo- hexyl) dithiophosphate ............... 5.5 3.0 8o 107 - ig oil B +. 0.50 / 0 barium-ß-butoxyethyl nonyldithiophosphate ................ 4.3 2.6 15 17 - ,;, 0 oil B + 0.5 0 /, barium di (decyldodecyl *) - dithiophosphate ..................... g, o 4.7 33.5 41 51 69 21 As sample 14 + 0.5 "/, tin-petroleum-sul- fonat ............................. 6, o 3.3 nothing 4.5 20 41 22 As sample 14 + 0.5 0 /, calcium-petroleum-sul- fonat ............................. 5.6 3.5 1.0 1.0 1.0 18 23 Oil B + o, 5 0 /, zinc di - (: z-butoxy-2-ethoxy- ethyl) dithiophosphate *) + 0.5 0/0 chromium Petroleum sulfonate ..................... 4.2 3.0 21 27 27 1 31 This compound was prepared from a mixture of alcohols containing 10 to 12 carbon atoms. It will be seen from the above results that the additives of the present invention not only achieve a very marked improvement over the simple mineral oils, but also show a surprising superiority over metal dithiophosphates of conventional types and approximately the same molecular weight, some examples of which are in the Tests 12, 13, 18 and 2o are listed. Tests 21 and 22 show that some additional improvements can be expected from using a metal petroleum sulfonate together.

Test 4: Lauson machine tests Tests were carried out in Lauson machines of the standard H-2 type under the following conditions: Jacket temperature ......... 98.9 ': L io / g' 01-sump temperature ....... 137.8 ' ± 10/90 duration of the exam ............ 6o hours. The test results were as follows: Piston paint condition of the class bearing oil used Test- (C. n. C.- ge 0/0 0/0 acid- No. lubricant eye weight viscosi_ insoluble grad loss of appearance in petroleum (mg Classical ether KOH zation) (mg) increase (boiling per under point 4o ') grams) 24 Oil A (1V4ttel of over? O tests ............ 6, z 92 39.9 0.94 1'04 25 Oil A + 0.5 % zinc-3-methoxy-n-butyl-2-ethyl- hexyldithiophosphate ......................... 6.5 4 14.3 0.25 0.39 26 Oil A + o, 8 0 /, Chromtetrahydrofurfuryloctylcresyl- dithiophosphate + 0.2% tin-petroleum sulfonate . . 6.5 1-2.5 * 43.6 0.48 0.50 It was observed in 2.5 tests that the deposit on the piston head was of a soft oily nature which could largely be removed by wiping, while in all of the tests carried out on 01 A this deposit was - # of a hard nature . Hard deposits are obtained in a similar manner when the simple metal dithiophosphates, as they are already known, are used.

The C.R.C. visual classification was carried out according to the method as used by the Coordinating Research Council for the classification of piston cleanliness is laid down in the standard ChevrOlet 36-hour L-4 test, in which a cleaner piston would have a class of io, o.

Test 5: 36-hour Chevrolet test Tests were carried out on a 6-cylinder Chevrolet engine of the standard type and according to Method L-4 of the Standard Coordinating Research Council. The following results were obtained: Through-texture cutting of the oil used corro- piston total total insoluble acid Test- Applied. Oil- lacquer- lacquer- sludge- 0/0 in Petro- grad No. Loss class class class Viscosil ether (rng Jun ts- (Boiling KOH whole increase point per Bearing (g) -1 1 1 under 40 ') grams) 27 ÖIA ..................... '...... 0.856 8.4 48.4 46, o 52.3 o, 85 o, 62 28 Oil A + oß (l /. Chromtetrahydro- farfuryloctylcresyldithiophosphate *) + 0.2 "/, tin petroleum sulfonate .... 0.158 8.9 48.9 47.0 43.8 0.54 0.34 This connection was the same as that used in test io. It will be understood that the present invention contemplates the use of materials prepared according to the methods herein described, such materials in some instances having minor amounts of impurities such as e.g. B. free dithiophosphoric acids and their sodium salts and possibly other compounds of indefinite composition.

The compounds described here can also be used in combination with other additives, e.g. B. viscosity index improvers or pour point depressants, be used.

Claims (4)

PATENT CLAIMS: i. . Mineral oil-based lubricant, characterized by a low content of oil-soluble metal salts of organically disubstituted dithiophosphoric acids, which are at least partially derived from a saturated aliphatic oxyether. ?. Lubricant according to claim i, characterized in that the oil-soluble metal salts have the general formula where n is the valence of the metal M, R, a saturated aliphatic radical which contains an ether group, and R, the same or a different organic radical, preferably a saturated aliphatic radical with at least 5 carbon atoms or an alkylated aromatic radical. 3. Lubricant according to claim i and 2, characterized in that as metal salts of dithiophosphoric acids, chromium salts or those of the 2nd and 3rd group of the periodic table, e.g. B. Alkaline earth or zinc salts are included. 4. Lubricant according to claim i to 3, characterized by a further low content of metal-petroleum sulfonates, for. B. alkaline earth or tin-petroleum sulfonates. References Cited: U.S. Patents Nos. 2 41o 65o, 2 242 26o.