Investigation of Antioxidative Properties of Multifunctional Additives of Alkyl Phenolate Type and Development of New Lubricant Compositions

The results of studies of the antioxidant properties of multifunctional alkylphenolate type additives indicate the calcium salts of condensation products of alkylphenols (C8 C12) with formaldehyde and the following amines: aminoacetic acid, benzotriazole, diethanolamine and boric acid, as well as their carbonated compounds. The determination of the antioxidant properties of the additives is tested on the АПСМ-1M apparatus. New lubricant compositions for diesel internal combustion engines oil meeting the required standards for these oils have been developed. The study of additives, which possess simultaneously detergent-dispersing, neutralizing, antioxidant anti-wear properties, revealed the dependence of antioxidant properties on their alkalinity.


Introduction
As is known, when developing motor oils intended for operation in diesel internal combustion engines, special attention is paid to the correct selection of the multifunctional additives that make up the composition as well as the physicochemical parameters of the base oils used. In this case, the synergism effect is achieved, which is that the total effect of the additive mixture is greater than the effect of each of them separately [1]- [6].

The Determination of the Antioxidant Properties of the Additives to Be Tested on the АПСМ-1M Apparatus (Method ВТИ GOST 981-75)
Among the additives used in the compositions an important place is occupied by antioxidant additives of phenolic type, it can be used for possibly creating new motor oils with improved antioxidant properties. Therefore, the purpose of the study is to investigate the stability of such additives-derivatives of alkylphenols containing active elements in their structures-heteroatoms (nitrogen, sulfur, boron) and metal (calcium) and identify among them the most effective methods for developing new lubricant compositions, combining them with additives of other types. {Therefore, the goal is set to investigate the stability of such additives-alkyl phenol derivatives containing the active elements-heteroatoms (nitrogen, sulfur, boron) and metal (calcium) in their structures, identifying among them the most effective methods to develop new low-ash lubricating compositions by combining them with additives of other types.} The use of calcium-containing additives in place of the traditional barium-containing additives is not only to increased ash content of the latter, but also to environmental problems associated with the emission of nanoparticles of harmful barium compounds together with the exhaust gases of the ICE. It should be noted that the high ash content of additives has a negative effect on the efficiency of exhaust gas purification systems, which are equipped with internal combustion engines that meet the requirements of Euro-4 and Euro-5 [7]. In this regard, a new direction is developing oils with low or {no} zero content of sulfate ash, phosphorus and sulfur both at home and abroad (Zow and Zero SAPS) [8]  To determine the dependence of the effect of the action on the structure of the test additives, their number is calculated from the need to develop a sample with an alkaline value of 5.5 -6.0 mg(KOH)/g (Table 1).  Figure 2 and Figure 3.  The content of the precipitate in the oxidized oil (X) in percent is calculated by the formula: where m-is the mass of oxidized oil, g; m 1 -sediment mass, g.
The results of the studies show that the investigated detergent-precipitating additives, being multifunctional, can sufficiently improve the antioxidant stability of the oils.
During oxidation of M-8 base oil (for 30 and 40 h at temperatures of 120˚C and 140˚C), the amount of precipitate formed is 1.122% and 2.042%, and at compound (A) is used (calcium salt of the condensation product of alkylphenol with formaldehyde and amino acetic acid), the precipitate is 0.152% and 0.927%, respectively. This is the reason for a sharp decrease in the acid number of oxidized oil and volatile low molecular weight acids.
The tests reveal that high efficiency of carbonated additives is obtained. Taking into account the high detergent-dispersing and, at the same time, antioxidant properties of additives, as well as a simple method for their preparation, engine oils of the БП, B 2 , and Г 2 groups are created with their participation.

Results and Its Discussion
For the test results, the arithmetic mean of two parallel determinations is taken. Table 1 shows the results of testing M-8 oil samples with additives and without additives.
As can be seen from the results of the comparative studies (Table 2)  The physicochemical parameters of the newly formulated compositions and the results of the studies are given in Table 3.

Conclusions
The multifunctional alkyl phenolate additives AKİ-218, AKİ-150 and AKİ-210 are investigated, their antioxidant properties are revealed and new lubricant compositions are created by using them. The composition with AKİ-218 addi-tive allows creating M-20БП engine oil, with AKİ-150 additive-M-14Г 2 oil, and with AKİ-210 additive-M-10B 2 engine oil meeting the required standards for these oils. {Thus, the investigated alkyl phenolate additives, being multifunctional, also possess antioxidant properties, and the new lubricating compositions created with them meet the required standards for engine oils of БП groups (ТУ 38 101593), Г 2 (GOST 8581), В 2 (GOST 12337) by combining phenolic type with known additives.}

Conflicts of Interest
The author declares no conflicts of interest regarding the publication of this paper.