PROTECTIVE LIQUID FOR HYDRAULIC SYSTEM, PREPARATION METHOD THEREFOR AND USE OF THEREOF

A protective liquid for a hydraulic system, the protective liquid comprising the following components in parts by weight: 24-33 parts of boric acid glyceryl amide, 17-22 parts of a carboxylic acid alcohol amine salt, 1-2 parts of sodium molybdate, 0.1-0.3 parts of methylbenzotriazole, 8-12 parts of glycerol and 30-50 parts of water, wherein the boric acid glyceryl amide is prepared by reacting boric acid, monoethanolamine and glycerol; and the carboxylic acid alcohol amine salt is a complex comprising 13-16 parts by weight of an undecanedicarboxylic acid triethanolamine salt and 4-6 parts by weight of a capryloyl glutamic acid triethanolamine salt. The protective liquid has an excellent anti-rust property and stability, a good sealing material adaptability, and a certain oiliness. When used at a concentration of 1-2%, the protective liquid can serve as a transmission medium for long-term protection of an external-injection-type single hydraulic prop, and actions such as supporting and lifting of the single pr