Main function and classification of dispersant lubricant additive   （二）

III. Function of dispersant

1. Dispersion effect

  The oil soluble group provided by the dispersant is larger than the purifier, which can effectively prevent the accumulation of carbon and colloidal material together. It can be 0 ~ 50nm sized particles by colloidal solution. These dispersants (succinimide) contain large polarity of ionization and disperse larger particles in the oil through charge repulsion. The alkyl molecular weight of the polymeric dispersant is very large, it can form a thick barrier film on the ions at many points, and the colloidal solution of up to 100nm particles, so the dispersant can effectively separate the particles from 0 ~ 100nm into the oil.

2. Solubilization

  Liquid polar substances that are insoluble in oil are dispersed into oil by interaction with dispersants, such as the dissolution of solutes. The sludge of engine oil is generated after some oxidation products are polymerized and mixed with condensate water. These polymers increase the carbon accumulation of engine oil, which is attached to the tank to prevent the suction of the oil pump, thus blocking the filter screen. The dispersant can directly interact with the carbonyl group, carboxyl group, hydroxyl group, nitro group, sulfate ester and so on, and dissolve these polar groups. Succinimide dispersants have the ability to form micelles with the above insoluble liquids, and complex with them to form oil-soluble liquids and disperse in the oil. The solubilization effect of dispersant is the best, about 10 times higher than that of detergent.

  It should be pointed out here that the polyene polyamine in dispersant also has a certain base value, which can also provide the total base value of the oil. Because the alkalinity of amine is weak alkalinity compared with the metal cleanser, it can not effectively neutralize the sulfuric acid and oxygen-containing acid generated after the combustion of oil products, there are still some acidic substances left over to cause corrosion of parts, so the alkali value provided by dispersant is not the real effective alkali value. The total alkalinity provided by the metal cleanser is effective. Lubrizol Company proved this point from the actual driving, although the total base value provided by the detergent and dispersant is relatively high, it can not slow down the growth rate of acid value in oil; While the total base value provided by the detergent alone is low, but the acid value of the oil is low.

IV. Succinimide

  Succimide is one of the most widely used dispersants. It has been widely used since the 1960s. This additive was introduced at the 7th World Petroleum Conference. Succinimide has Mono-Succinimide (Mono-Succinimide), Bis-Succinimide (bis-Succinimide), Poly-Succinimide and High Molecular Weight dispersant Dispersant) depending on performance and usage. The low temperature dispersion of monosuccinimide is particularly good, which is mostly used in gasoline oil and diesel engine oil below APICC grade. Bis and dobutylimide have good thermal stability and are used more in supercharged diesel engine oil. The later development of High Molecular Weight Succinimide (High Molecular Weight Succinimide), not only the molecular size of PIB becomes larger, but also a PIB connected with about two maleic anhydride to adapt to the new development of advanced oil products requiring higher dispersion. The high molecular weight dispersant has good high temperature cleanness and sludge dispersion performance. It is used for high-grade internal combustion engine oil, and can also significantly reduce the amount of dispersant used for lower grade SE and SF oil. Monosuccinimide generally with molecular weight about 1300 polyisobutylene, bisand polysuccinimide with molecular weight about 1000 polyisobutylene, high molecular weight succinimide with molecular weight about 2000 polyisobutylene. The number of maleic anhydride, nitrogen content and molecular weight of PIB in the dispersant were investigated. The greater the viscosity of lubricating oil, the worse the dispersion, and vice versa. Or it was found that the higher the nitrogen content and the higher the average maleic anhydride content, the better the dispersion.

  Succinimide is mainly used in internal combustion engine oil. The proper combination of succinimide and high base value detergent not only make up for each other's shortcomings, but also ensure the overall performance and have excellent synergy effect. That is, the two can form complex micelles, which can significantly enhance the solubilization under the stable action. Especially because of the strong neutralization capacity of the high base value metal detergent, it can timely neutralize those acidic oxidation products as the mother oil sludge, so as to protect the solubilizing ability of succinimide from being consumed by these products quickly, so that succinimide can fully maintain and play its role as a dispersant; At the same time, it maintains the strong dispersion ability of imide succinate, and can improve the stability of a large number of alkali components (CCaCO3 and other particles) in the oil of high alkali value metal cleaning agent, and is not easy to accelerate depletion due to precipitation in the process of use. So modern internal combustion engine oil, are high base value of the detergent and succinimide and other ash free agent appropriate compound.

  Dispersants produced by Liaoning Hongyi Chemical Co., Ltd. mainly include Mono-Succinimide HY151 (Mono-Succinimide), Bis-Succinimide HY154 (BIS-Succinimide), polysuccinimide HY155 (Poly-Succinimide) and high molecular weight dispersant HY161 (High Molecular Weight Dispersant).

Product index：

  In short, dispersant is generally used in modern automobile engine oil, the dosage of 1% ~ 6%, mainly control sludge. Adding the same amount of dispersant is particularly effective for smoke point control of automotive diesel engine oil. Railway locomotive oil requires good alkali reserve and high dispersion property, which needs to be provided by adding dispersant. Medium speed cylinder piston engine oil tends to use a smaller amount of dispersant, generally adding 2% to 4%; At present, Marine cylinder oil has begun to use a small amount of dispersant, the addition of dispersant can not only improve the clean dispersability of Marine cylinder oil, but also greatly reduce the addition of high alkaline additives, reducing the cost. Two-stroke gasoline engine oil is mixed with lubricating oil and fuel oil, too much metal detergent and antioxidant, easy to produce wear and ring bonding, in order to prevent the occurrence of such events, often use a separate special dispersant or combined with detergent. It should be proposed that the dispersant of succinimide type will increase the low temperature viscosity due to the low molecular polyisobutene group, which brings difficulties to the preparation of multistage oil. If the polymer dispersant (viscosity index improver) is added to replace part of the dispersant, it can not only improve the low temperature performance, but also provide enough low temperature dispersant.