Process for preparing NCO-terminated polyurethanes, said polyurethane being non-solid at a temperature ranging from 5 to 35°C and having a Brookfield viscosity measured at 23°C according to standard ISO 2555 of less than or equal to 300 000 mPa.s, said process comprising, successively: a) the reaction of a composition of diisocyanate(s) with a composition of polyol (s) with an NCO/OH molar ratio less than or equal to 0.8 in order to obtain an OH-terminated precursor polyurethane comprising no terminal NCO functions, said composition of diisocyanate(s) comprising at least 80% by weight, relative to the total weight of the composition of diisocyanate(s), of a diisocyanate selected from diphenylmethylene-4,4'-diisocyanate (4,4'-MDI), IPDI, toluene diisocyanate (2,4-TDI), meta-xylylene diisocyanate (m-XDI), the allophanate derived from hexamethylene diisocyanate of formula below: in which: - p is an integer ranging from 1 to 2; - q is an integer ranging from 0 to 9, and preferably from 2 to 5; - R represents a saturated or unsaturated, cyclic or acyclic, linear or branched hydrocarbon-based chain comprising from 1 to 20 carbon atoms, preferably from 6 to 14 carbon atoms; - R' represents a divalent alkylene group having from 2 to 4 carbon atoms; and preferably a divalent propylene group; and b) the reaction of said OH-terminated precursor polyurethane obtained in this way with a diphenylmethylene diisocyanate composition in an NCO/OH molar ratio strictly greater than 1 in order to obtain NCO-terminated polyurethanes, said diphenylmethylene diisocyanate composition comprising at least 80% by weight of the same diphenylmethylene diisocyanate compound, steps a) and b) being carried out under anhydrous conditions. a) the reaction of a composition of diisocyanate(s) with a composition of polyol (s) with an NCO/OH molar ratio less than or equal to 0.8 in order to obtain an OH-terminated precursor polyurethane comprising no terminal NCO functions, said composition of diisocyanate(s) comprising at least 80% by weight, relative to the total weight of the composition of diisocyanate(s), of a diisocyanate selected from diphenylmethylene-4,4'-diisocyanate (4,4'-MDI), IPDI, toluene diisocyanate (2,4-TDI), meta-xylylene diisocyanate (m-XDI), the allophanate derived from hexamethylene diisocyanate of formula below: in which: - p is an integer ranging from 1 to 2; - q is an integer ranging from 0 to 9, and preferably from 2 to 5; - R represents a saturated or unsaturated, cyclic or acyclic, linear or branched hydrocarbon-based chain comprising from 1 to 20 carbon atoms, preferably from 6 to 14 carbon atoms; - R' represents a divalent alkylene group having from 2 to 4 carbon atoms; and preferably a divalent propylene group; and - p is an integer ranging from 1 to 2; - q is an integer ranging from 0 to 9, and preferably from 2 to 5; - R represents a saturated or unsaturated, cyclic or acyclic, linear or branched hydrocarbon-based chain comprising from 1 to 20 carbon atoms, preferably from 6 to 14 carbon atoms; - R' represents a divalent alkylene group having from 2 to 4 carbon atoms; and preferably a divalent propylene group; and b) the reaction of said OH-terminated precursor polyurethane obtained in this way with a diphenylmethylene diisocyanate composition in an NCO/OH molar ratio strictly greater than 1 in order to obtain NCO-terminated polyurethanes, said diphenylmethylene diisocyanate composition comprising at least 80% by weight of the same diphenylmethylene diisocyanate compound,