METHOD OF PREPARING THICKENING AGENT Russian patent published in 2002 - IPC

FIELD: lubricants. SUBSTANCE: thickening agent used in production of various-type lube oils is prepared by mixing polymer with oil and dissolving it in the latter. Utilized polymer is high-molecular polyisobutylene, butyl rubber, ethylene/propylene rubber, or a mixture thereof, which is subjected to thermomechanical destruction in fourzone reactor, and resulting product with molecular mass between 4000 and 30000 is mixed (at simultaneous dissolution and cooling) in the fifth zone with transformer and/or industrial oils at weight ratio polymer/oil between 9:1 and 3:1. Cooling is accomplished simultaneously by external (over jacket) and internal (directly in mixing zone) cooling agents, in particular by base oil. Further, in another apparatus, stirring is accompanied by introduction for 2 h of additional amount oil to achieve final concentration of polymer 20 to 50 wt %. Oil can also contain 0.005-0.1 wt % of additive selected from following compounds: 4-methyl-2,6-di-tert-butylphenol, 2,2-methylene-bis(4-methyl-6-tertbutylphenol), and dilauryl thiodipropionate. EFFECT: enabled preparation of thickening agent with elevated depolymerization resistance and thickening capability, and long-storage stability. 2 cl, 7 ex