Sulphur orthophosphate compositions, preparation and use

A sulphurized orthophosphate composition (SOPC), comprising a mixture of sulphurized mono- and di-ester phosphates, in acid or salified form, and optionally tri-ester phosphates, wherein said mixture comprises:

• (i) at least one compound of formula (1)(R1—O)3—P═O or a salt of this compound,
• in which formula the R1 radicals, which are identical or different, represent:
• at least one of them, the R1—(O—X)n-radical:
• in which
• R1 is a hydrogen atom or a saturated or unsaturated, linear, branched or cyclic, hydrocarbonaceous radical comprising 1 to 30 carbon atoms,
• X is a linear or branched alkylene radical comprising 2 to 4 carbon atoms,
• n having a mean value of between 1 and 100,
• a hydrogen atom,
• a saturated or unsaturated, linear, branched or cyclic, hydrocarbonaceous radical comprising 1 to 30 carbon atoms,
• at least one of the R1 radicals of a molecule of compound of formula (1) being connected to another R1 radical of another molecule of compound of formula (1) via one or more mono- or polysulphide bridges using S—C bonds;
• (ii) and in that it exhibits a level of sulphur ranging from 1 to 50% by weight.