Aqueous composition for lubricating mechanical systems

The aqueous lubricant composition as claimed in any one of the preceding claims, comprising from 0.01% to 5.0% by mass, preferably from 0.05% to 3.5% by mass, more preferentially from 0.1% to 1.5% by mass of hypericin, relative to the total mass of the composition.

The aqueous lubricant composition as claimed in any of the preceding claims, also comprising at least one additive chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, antiwear and/or extreme-pressure additives, sequestrants, metal passivating agents, dyes, dispersants, emulsifying agents, and mixtures thereof, preferably chosen from antifoaming agents, extreme-pressure agents, corrosion inhibitors, pH regulators, metal passivating agents, dyes, and mixtures thereof.

The aqueous lubricant composition as claimed in any of the preceding claims, comprising less than 5% by mass, preferably less than 2% by mass, more preferentially less than 1% by mass of water-insoluble oil(s), relative to the total mass of said composition.

The aqueous lubricant composition as claimed in any of the preceding claims, said composition being free of water-insoluble oil.

The use of an aqueous lubricant composition as claimed in any of the preceding claims, for lubricating moving parts in a mechanical system, in particular in a vehicle propulsion system.

The use of hypericin as an additive for improving the tribological properties, in particular in terms of friction reduction and wear resistance, of an aqueous composition moreover comprising at least water and glycerol.

The use as claimed in the preceding claim, said aqueous composition comprising at least 35% by mass of water and at least 20% by mass of glycerol, relative to the total mass of said composition.