DE1154218B - Lubricating oil additive and lubricating oil containing it - Google Patents

Description

Lubricating oil additive and lubricating oil containing it Long ago At that time it was recognized that lubricating oils such as simple mineral oil raffinates which are placed on them when they are used as engine or gear oils, not suffice. Efforts were therefore made to overcome certain disadvantages of the base oils from petroleum distillation or to remove them from the Fischer-Tropsch synthesis by adding various types, a development that led to the so-called alloyed oils. One of the main drawbacks the base oils is z. B. their inadequate temperature viscosity index. Another The disadvantage is their lack of film strength on metals. The latter is the reason for the fact that when large loads are transmitted, for example via the gears of a transmission, the oil film can collapse, so that practically the conditions and thus approximate the wear values of dry running can also be achieved. Another requirement that one puts in engine and gear oils is the development of an anti-corrosive one Effect on both the lubricated parts and the oil itself. this all are properties that unalloyed oils only have imperfectly. As for oil corrosion or oil aging, it is easy to see that the Degradation of an oil, especially in the presence of oxygen, by the metallic one Abrasion is favored catalytically. Additives useful in this direction should therefore have an inhibiting effect.

Two further points of great practical importance are the "detergent effect" and the "dispersant effect", whereby certain additions - one denotes such as »HD« or »DD« additions, i. H. "Heavy-duty" or "detergent-dispersant" additives Cleaning effect on the parts to be lubricated is exerted by both the metallic Abrasion as well as charring residues from the metallic surfaces automatically removed and dispersed in the oil.

One may now consider the strength of an oil film or the oil and Metal corrosion and finally the detergent and dispersant effect: in all of these In some cases it is a question of interface problems. It is therefore not surprising that most of the additions are in principle structured in the same way and are in their More or less overlap the area of effect. It is also evident that Such additives are surface-active or interface-active substances, so substances of their Molecules consist of a strongly polar part and an oleophilic part. At a "EP" oil (extreme pressure oil) is created by the interface-active substance between Metal and oil film, as it were, created a bonding bridge by adding the additional molecules with their polar part cover the metal surface, while their oleophilic part protrudes in oil; it is easy to see that this results in a higher mechanical strength of the oil film results.

Numerous compounds are now known as additives, from simple metal soaps to complex sulfur-phosphorus compounds. A large number of patents describe the boiling of partly oxygen-free, partly oxygen-containing low molecular weight and higher molecular weight organic compounds with phosphorus sulfides; the reaction products obtainable in this way are then treated with metal oxides, in particular barium, calcium or zinc oxide. Defined dithiophosphoric acid esters and their salts, as obtained by reacting higher alcohols with phosphorus pentasulfide and then neutralizing the ester acid with metal oxides, such as Zn-0,0-dihexyldithiophosphate, are of particular importance. It is also known to use dithiophosphoric acid derivatives at the same time as organic polysulphides. For example, in German Auslegeschrift 1 042 807, mixtures of an oil-soluble dithiophosphoric acid triester, a metal salt of dithiophosphoric acid diesters, a bis-dithiophosphoric acid diester or a dithiophosphoric acid-thiophosphoric acid diester or a dithiophosphoric acid-thiophosphoric acid diester Di (aralkyl) polysulfide described as lubricating oil additives. In this interpretation it is pointed out (column 10, line 4 ff.) That a satisfactory effect is only achieved when both components are present in critical amounts. Efforts have recently been made to build up ashless additives.

It has now been found that mixtures or reaction products from 10 to 90 percent by weight of an O, O-dialkyldithiophosphoric acid ester known as a lubricating oil additive and 90 to 10 percent by weight of a reaction product of maleic or fumaric acid alkyl esters and sulfur are excellent additive for lubricating oils. The term "alkyl" means in all cases an unbranched or branched aliphatic or cycloaliphatic Hydrocarbon radical of 4 to 22 carbon atoms. Mixing the components can be at room temperature or at a higher temperature, e.g. B. at 120 ° C, take place, a reaction occurs when working at a higher temperature. These products are compatible with lubricating oil in all proportions and are the base oils in Amounts from 0.2 to 100/0, preferably 0.5 to 3 percent by weight, based on the Lubricating oil base, added.

The preparation of the O, O-dialkyldithiophosphoric acid esters is known. The production of the sulphurized maleic or fumaric acid esters can be carried out according to A. Michael, Ber., 28, p. 1633 (1895), take place by, for example, 1 mol of fumaric acid ester with 1 gram atom or an excess of sulfur at a higher temperature for a longer period of time is heated; after the reaction has ended, it is allowed to cool and the unreacted is separated Esters and sulfur. The named author describes the resulting reaction product as diethyl episulfidosuccinate. Based on the molecular weight determinations carried out by us and other responsiveness, however, it is likely that it will this ester is its dimer, which has approximately the constitution of 1,4-dithiacyclohexane-2,3,4,5-tetracarboxylic acid tetraethyl ester should come.

The additives according to the invention make the base oils essential improved. This gives products that z. B. suitable as running-in oils or hypoid oils are. The additives which can be prepared according to the invention impart to the base oils in many cases Properties as required by "HD" and "EP" oils. As lubricating oils, to which the additives of the invention are added are suitable animal, vegetable or synthetic products, but mainly those like those at the processing of petroleum.

The products according to the invention were tested using a lubricimeter after A. Bartel, E. H. Kadmer, S. Moos and Gg. R. Schultze (HE test): Investigations on wear and friction, "Lubrication Technology", issue 4, October / December, 3rd year 1956, pp. 184 to 191, as well as according to the FZG gearwheel short test according to N i e m a n n (cf. G. Niemann, H. Rettig and G. Lechner, »Experiences with the transmission oil test in Zahnradverspannungsprüfstand ", Erdöl und Kohlen, 12, pp. 472 to 480 [1959], and G. Niemann and H. Rettig, "The FZG short gear test for testing gear oils," Petroleum and Kohl, 7, pp. 640 to 642 [1954]).

The additives according to the invention were found in both test methods as superior effective. In the Niemann test, for example, a base oil with the addition of a Combination of sulphurized dibutyl fumarate and O, O-dialkyldithiophosphoric acid ester, as described in example 1, the maximum achievable. While that used unalloyed base oil already at load level 7 and an alloyed standard oil, such as it is used commercially as a gear oil, at which load level 10 failed, was at a dl with the above-mentioned addition reaches a damage load level above 12, d. In other words, at the highest load level, no gear damage whatsoever could be seen, with a specific wear Vs below 0.1 mg / PSh. This was also shown in the IfE test same oil excellent properties; 3 as wear values (g - 10-4) in the normal test 0.98, in the fast run test 0.58 and in the emergency run test 2.88 after 43 minutes measured. In comparison, the corresponding values for the dithiophosphoric acid ester component and wear values of 0.80 (normal test), 4.82 (fast running test) and 2.20 (Follow-up test) found after 19 minutes and 30 seconds. The sulphurized Fumaric acid ester as the sole additive caused wear of 3.01 in the normal test. This comparison therefore reveals the advantages of combinations according to the invention see clearly. While the sulphurized fumaric acid ester does not have any on its own results in interesting effects, it unfolds together with the dithiophosphoric acid ester a much better effect - also compared to dialkyldithiophosphoric acid ester alone - which is particularly evident in the fast run test, but also in the emergency run test, where the seizure occurs much later after the oil supply has been switched off.

In addition to the combinations according to the invention, the lubricant additives can be used contain other known additives, e.g. B. those that improve viscosity are suitable.

The following are the manufacture, use and testing of the new additions are explained. A. Preparation of the phosphorodithioic acid esters The preparation of the O, O-dialkyldithiophosphoric acid esters is known and is not Subject of this invention.

A preferred method is to wear at a slightly elevated temperature Phosphorus pentasulfide gradually into the mixture until the completion of the reaction of the alcohol with an inert solvent. After filtration and removal of the solvent, the products can be obtained by distillation or crystallization of their Salts are further purified. In the manufacture of the products according to the invention however, further cleaning operations can generally be dispensed with.

B. Preparation of the sulfurized maleic or fumaric acid esters Manufacture of these products can be done on the basis of a regulation the sulfur is reacted with fumaric acid diethyl ester (L. H. Flett, W. H. Gardner, Maleic Anhydride Derivatives, New York and London, 1952, p. 219; see also A. Michael, Ber :, 28, p. 1633 [1895]).

C. Preparation and testing of the additional mixtures Example 1 251 parts by weight of an O, O-dialkyldithiophosphoric acid ester obtained by reacting phosphorus pentasulfide with a commercially available fatty alcohol mixture, the alcohols of which have chain lengths of 12 containing up to 18 carbon atoms, so that the alkyl radical is a mixture from C12 to C18 residues represents, and has an acid number of 100 has, with 130 parts by weight of a sulfurized fumaric acid dibutyl ester 12 Heated to 120 ° C for hours. There are 370 parts by weight of a dark brown, clear Obtained oil of n ö = 1.4780, which is compatible with lubricating oil in all proportions is.

IfE test The IfE test was carried out as follows: Normal test [3 hours at 150 rpm, sliding speed 0.2 m / sec, load 4500 kg / cm2; Raschlauf [1 Hour at 450 rpm, sliding speed 0.6 m / sec, load 4500 kg / cm2; Emergency run [3 hours normal test, then oil supply switched off; the device is shut down at Start of seizure (indication of time and wear and tear at this point in time).

2% solutions of the additives in a base oil from Deutsche Gasolin-Nitag (SAE 90, d2 ° = 0.918) were used. Niemann test This test was also carried out with "Gasolin" base oil SAE 90 with a content of 2% of the additive according to the invention. Circulation speed (v) .... 8.3 m / sec Speed (. L) ................ 2175 rpm Sliding speed at the tooth tip (VB) ......... 0.675 - v (m / sec) Initial oil sump temperature .. 90 ° C Test result Damage load level ......... above 12 Specific wear (VS). below 01, mg / PSh Example 2 121 parts by weight of dithiophosphoric acid O, O-diisobutyl ester are mixed with 130 parts by weight of sulphurized fumaric acid diisobutyl ester and heated at 120 ° C. for 6 hours. The dark brown oil produced in this way, ö 1.4860, can be mixed with lubricating oil in any ratio. The test in the IfE test showed that this additive is suitable for running-in oils.

Example 3 By mixing 151 parts by weight of O, O-dialkyldithiophosphoric acid ester, in which the alkyl radical is a mixture of C12- to C "-alkyl radicals, with 60 parts by weight of sulphurized fumaric acid dialkyl ester, in which the alkyl radical is also a mixture of C12- to C1, -alkyl radicals, At room temperature, a clear, medium-brown oily product is obtained which is compatible with lubricating oil in all proportions. The O, O-dialkyldithiophosphoric acid ester and the dialkyl fumarate contain alkyl groups with 12 to 18 carbon atoms as ester components. This combination, in an amount of 5 ° / o Added to a base oil, results in a good quality gear oil.

Example 4 151 parts by weight of O, O-dialkyldithiophosphoric acid ester, in which the alkyl radical contains 12 to 18 carbon atoms, are heated to 120 ° C. with 112 parts by weight of sulphurized di (2-ethylhexyl) fumarate for 25 hours. The result is a brown oil with a front n ö ° = 1.4776, which has unlimited compatibility with lubricating oil and is suitable as a gear oil additive.

Example 5 30 parts by weight of 0,0-dibutyldithiophosphoric acid ester are mixed at room temperature with 130 parts by weight of sulfurized dibutyl fumarate. the The combination obtained in this way is suitable for the production of run-in oils.

Claims (2)

PATENT CLAIMS: 1. Lubricating oil additive, consisting of a mixture from a) 10 to 90 percent by weight of an O, O-dialkyldithiophosphoric acid ester known as a lubricating oil additive and b) 90 to 10 percent by weight of a reaction product of sulfur with maleic or. Fumaric acid alkyl esters, the alkyl group of which is unbranched or branched aliphatic or cycloahphatic hydrocarbon radicals with 4 to 22 carbon atoms, or from reaction products obtained from the components at a higher temperature a) and b). 2. Lubricating oil, characterized by a content of 0.2 to 10 percent by weight, preferably 0.5 to 3 percent by weight, based on the lubricating oil base, of one Additive mixture or reaction product according to claim 1.