Anti-wear composition for lubricating oils

Abstract

FIELD: production of lubricants.SUBSTANCE: antiwear composition for lubricating oils based on oil-soluble metal dialkyl dithiophosphate is proposed, containing oil-soluble dialkyl dithiophosphate of divalent iron with alkyl radicals from 80 to less than 100 and a diester of dithiophthalic acid with aliphatic alcohols from more than 0 to 20.EFFECT: increasing the anti-wear properties of lubricating oils and increasing the resistance of the anti-wear component to hydrolysis.1 cl, 3 tbl, 5 ex

Description

[0001] The invention relates to the field of mechanical engineering and the production of lubricants; the composition can be used for introduction into motor, transmission, industrial oils and plastic lubricants.

[0002] The anti-wear additive PAF-4 is known from the prior art, which is molybdenum diisobutyl isoctyl dithiophosphate.

[0003] This additive is inferior to the claimed solution in terms of its effect on the anti-wear properties of lubricating oils due to the absence of a component in its composition that enhances anti-wear properties, as well as due to the short length of isobutyl and isooctyl radicals.

[0004] Also known from the prior art is a composition comprising molybdenum dialkyl dithiophosphate (RU Patent No. 2122568, IPC C10L1 / 18, published November 27, 1998). A disadvantage of this composition is that its use in lubricating oils is impractical due to the destruction of the additive during long-term use.

[0005] An anti-wear composition is known (patent for invention of the Russian Federation No. 2627771, IPC C10M 137 / 10, C10M 141 / 10, C10N 30 / 06, published on 11.08.2017), which contains molybdenum dialkyl dithiophosphate with alkyl radicals containing 12 or more carbon atoms, and a diester of maleic acid with alkyl radicals containing 12 or more carbon atoms.

[0006] The disadvantages of this composition are lower anti-wear properties than those of the claimed solution and lower resistance of molybdenum dialkyl dithiophosphates to hydrolysis.

[0007] The closest in composition to the claimed solution is the anti-wear composition (patent for invention of the Russian Federation No. 2665693, IPC C10M 137 / 00, C10M 137 / 10, C10M 141 / 10, C10N 30 / 06, C10L, published 09 / 04 / 2018), which contains molybdenum dialkyl dithiophosphate with alkyl radicals containing 12 or more carbon atoms, and thiophthalic acid diester with alkyl radicals containing 12 or more carbon atoms. This composition is more resistant to a decrease in anti-wear properties than a composition including molybdenum dialkyl dithiophosphate and maleic acid diester, but does not completely solve the problem of combining higher anti-wear properties than zinc dialkyl dithiophosphates with resistance to the destruction of the components of the composition as a result of hydrolysis and oxidation-reduction reactions with friction unit materials.A fundamental drawback of molybdenum dialkyl dithiophosphates is the low stability of molybdenum ions in low oxidation states (primarily trivalent) to oxidation reactions that produce molybdenum ions in the (IV) oxidation state. This leads to hydrolysis of the dialkyl dithiophosphates due to a sharp decrease in the basicity of molybdenum (IV) oxide compared to molybdenum (III) oxide. The resulting dialkyl dithiophosphoric acids have low solubility in the hydrocarbon bases of lubricating oils in the presence of water and precipitate or separate in oil filters. This leads to a decrease in the additive content of lubricants and a reduction in their antiwear properties during operation or storage.

[0008] The technical result of the claimed invention consists in increasing the anti-wear properties of lubricating oils and increasing the resistance of the anti-wear composition based on metal dialkyl dithiophosphate to hydrolysis.

[0009] The specified technical result is achieved due to the fact that the anti-wear composition for lubricating oils according to the invention contains oil-soluble ferrous alkyl dithiophosphate with alkyl radicals containing 12 or more carbon atoms and a diester of dithiophthalic acid with aliphatic alcohols containing 12 or more carbon atoms, wherein the initial components are taken in the following ratio, wt.%:

[0010] iron(II) dialkyl dithiophosphate - 80-100;

[0011] Dithiophthalic acid diester - 0-20.

[0012] According to the experimental data obtained by the authors, diesters of thiophthalic acid with aliphatic alcohols containing 12 or more carbon atoms enhance the antiwear properties of metal dialkyl dithiophosphates and increase the latter’s resistance to hydrolysis.

[0013] The use of compositions containing less than 80 wt.% of iron (II) dialkyl dithiophosphate and more than 20 wt.% of dithiophthalic acid diester is not advisable due to the lack of enhancement of the combined effect with a significant excess of the diester.

[0014] The use of compositions containing 100 wt.% iron (II) dialkyl dithiophosphate is also advisable, since it leads to an increase in antiwear properties compared to the use of similar zinc dialkyl dithiophosphates and an increase in stability compared to molybdenum dialkyl dithiophosphates.

[0015] The composition was prepared as follows.

[0016] Ferrous dialkyl dithiophosphate (FeDDP) was obtained by reacting hexadecanol-1 with phosphorus pentasulfide in a 4:1 molar ratio, followed by neutralization of the resulting dialkyl dithiophosphoric acids with ferrous oxide. Zinc dialkyl dithiophosphates (ZDDP) and molybdenum trivalent dialkyl dithiophosphates (MoDDP) were obtained similarly. Note: molybdenum (III) oxide was obtained by reducing molybdenum (VI) oxide with aluminum powder in an alkaline medium; MoDDP can also be obtained by reacting dialkyl dithiophosphoric acid with metallic molybdenum powder, but this method results in the presence of molybdenum (IV) salts.

[0017] Dithiophthalic acid diester was obtained by reacting phthalic anhydride with hexadecanol-1 in a molar ratio of 1:2 under the catalysis of anhydrous orthophosphoric acid and then reacting the resulting phthalic acid diester with phosphorus pentasulfide in a molar ratio of 5:2.

[0018] Example 1. Compositions are prepared by mixing 0.5% by weight, 1.0% by weight and 1.5% by weight of iron (II) dihexadecyl dithiophosphate in I-40A industrial oil.

[0019] For comparison, prototype compositions (examples 2 and 3) containing molybdenum and zinc dihexadecyl dithiophosphates were used.

[0020] Example 2. Compositions are prepared by mixing 0.5% by weight, 1.0% by weight and 1.5% by weight of zinc dihexadecyl dithiophosphate in I-40A industrial oil.

[0021] Example 3. Compositions are prepared by mixing 0.5% by weight, 1.0% by weight and 1.5% by weight of molybdenum (III) dihexadecyl dithiophosphate in I-40A industrial oil.

[0022] The anti-wear properties of the obtained compositions were compared during tests according to GOST 9490-75, clause 3.9. on a ChMT-1 friction machine under an axial load of 396 N. The test results are presented in Table 1.

[0023] Table 1 - Test results of tribological characteristics of lubricating compositions based on FeDDP, ZDDP and MoDDP in I-40A oil: wear scar diameters

[0024] Content in I40A oil 0.5% by weight 1.0% wt. 1.5% by weight Example 1 0,56 0,45 0,40 Example 2 0.62 mm 0,52 0,47 Example 3 0.54 mm 0,44 0,38

[0025] As can be seen from Table 1, iron (II) dialkyl dithiophosphate is significantly superior to zinc dialkyl dithiophosphate in terms of antiwear properties and is slightly inferior to molybdenum (III) dialkyl dithiophosphate.

[0026] The hydrolysis resistance of the obtained compositions (Examples 4 and 5) was compared in tests according to GOST 9490-75, clause 3.9, on a ChMT-1 friction machine under an axial load of 396 N. The test results are presented in Table 2.

[0027] Example 4. 1.5% by weight of iron (II) dialkyl dithiophosphate was added to I-40A oil. After complete dissolution, 5% by weight of water was added and the mixture was maintained at a temperature of 90°C for three cycles of 8 hours. The total time was 24 hours.

[0028] Example 5. 1.5% by weight of molybdenum (III) dialkyl dithiophosphate was added to I-40A oil. After complete dissolution, 5% by weight of water was added and the mixture was maintained at a temperature of 90°C for three cycles of 8 hours. The total time was 24 hours.

[0029] The results of tribological tests are shown in Table 2.

[0030] Table 2 - Test results of tribological characteristics of lubricating compositions based on FeDDP and MoDDP in I-40A oil after interaction with water

[0031] Composition Wear spot diameter, mm Example 4 0,41 Example 5 0,44

[0032] As can be seen from the results shown in Table 2, the ferrous dialkyl dithiophosphate (the claimed solution) in the lubricating oil is significantly more resistant to hydrolysis than the trivalent molybdenum dialkyl dithiophosphate (prototype).

[0033] The efficiency of introducing dihexadecyl thiophthalic acid ester into a lubricating composition was determined by comparative testing of a 1% solution of iron (III) dihexadecyl dithiophosphate in I-40A industrial oil (Example 1) with I-40A oil containing 1% by weight of iron (III) dihexadecyl dithiophosphate and additionally various amounts of dihexadecyl thiophthalic acid ester in the range of 0.01...0.3% by weight (Example 6).

[0034] Example 6. A composition is prepared by mixing 1.0% by weight of iron (II) dihexadecyl dithiophosphate with I-40A industrial oil. Then 9 compositions are prepared by adding 0.05, 0.1, 0.125, 0.150, 0.175, 0.2, 0.25 and 0.3% by weight of dihexadecyl thiophthalate to this composition.

[0035] The comparison was carried out during tests according to GOST 9490-75 clause 3.9. on a ChMT-1 friction machine with an axial load of 396 N. The test results are presented in Table 3.

[0036] Table 3 - Test results of tribological characteristics of lubricating compositions based on FeDDP in I-40A oil with additives of dihexadecyl thiophthalic acid ester (DETFA)

[0037] Content of DETPhK, % by weight 0 0,05 0,1 0,125 0,150 0,175 0,2 0,25 0,3 Wear spot diameter, mm 0,45 0,43 0,42 0,41 0,39 0,42 0,43 0,46 0,48

[0038] As can be seen from the data presented in Table 3, some increase in the antiwear properties of the composition is achieved with the addition of dihexadecyl thiophthalate (DETPA) in an amount of 5% of the FeDDP amount. The maximum effect is achieved with the addition of 12-15% of the FeDDP amount and is observed up to a DETPA content of 20% of the FeDDP amount. At higher DETPA contents, a negative effect is observed.

[0039] The resulting composition improves the anti-wear properties and hydrolytic stability of lubricating oils and can be used for introduction into transmission, hydraulic and other industrial oils, as well as into plastic lubricants.

Claims

An antiwear composition for lubricating oils based on oil-soluble metal dialkyl dithiophosphate, characterized in that it contains oil-soluble dialkyl dithiophosphate of divalent iron with alkyl radicals containing 12 or more carbon atoms, and a diester of dithiophthalic acid with aliphatic alcohols containing 12 or more carbon atoms, wherein the initial components are taken in the following amount, wt.%: iron (II) dialkyl dithiophosphate from 80 to less than 100 and a diester of dithiophthalic acid from more than 0 to 20.