Detergent-dipersant additive for lubricating oils of internal combustion engines and its preparation process

An additive for lubricating oils of internal combustion engines containing the imide- and/or ester and/or ester-amide, derivatives of the reaction product of an unsaturated polyisobutylene and some unsaturated reactive dicarboxylic acids and/or their anhydride comprising the reaction product of a polyisobutylene of a number average molecular weight 800 - 30 000 and an unsaturated reactive dicarboxylic acid and/or its anhydride, preferably maleic anhydride containing 1.6 - 6.0 SA - derivative per polyisobutylene chain on the average having a concentration of molecules containing more than one SA - derivative more than 25 weight percent and the polyisobutylene is grafted or reacted with an SA containing copolymer formed from a more reactive, low molecular weight comonomer of a molecular weight less than 500, containing olefinic double bond or from a mixture of such comonomers and from unsaturated reactive dicarboxylic acid and/or their anhydride, preferably maleic anhydride using the molar ratio 1.2 - 5.5 : 0.1 - 3.5 : 1 = MAH : comonomer : polyisobutylene, and in which the widening of the molecular weight distribution is less than 70 percent, referred to the starting polyisobutylene, while the SA groups of the copolymer linked to the polyisobutylene are reacted, in a 0.7 - 5.5 ratio, with compound containing at least bifunctional amine and/or hydroxyl groups. The invention disclosed the process of preparation of the additive.