Water-dispersible copolyamide

A water-dispersible copolyamide comprising at least four different polyamide units, in which:

• at least one of said polyamide units includes at least one sulfonate group, said polyamide sulfonate unit being present in a content of at least 15% by weight;
• and
• at least two of said polyamide units are derived from aliphatic monomers;
• it being understood that said copolyamide does not include more than 20% by weight of caprolactam-based unit, that it has a glass transition temperature of between 10° and 140° C. as measured by DSC according to the standard NF EN ISO 11 357-2 with a heating rate of 20° C./minute, and an inherent viscosity of greater than 0.4 dl/g as measured by applying the standard ISO 307:2007, but at 20° C. in a solution at 0.5% by weight in m-cresol.